Why don't you just go ahead and ask your questions? Regulars who come here to help appreciate feed back and some kind of dialogue that's all. You may want to see if some of what you ask has not been answered before, in your search you will discover that some questions have a general answer but others come with a "it all depends" attached.

I agree with Ink - this is a good a place as any for your questions :-)

This forum is certainly not restricted to professionals. While there are a number of professionals that post here on a regular basis, often in response to non-professionals' questions, there are many ordinary homeowners and DYI'ers that participate as well. Many are quite accomplished designers in their own right and have very good advice and opinions to offer.

Ink makes a good point about developing a dialogue - often posters will pose a question that generates a very helpful and enlightening discussion, only to have the OP never be heard from again. We call 'em "hit and runs" :-) Those can be tiresome as we never know how the advice was utilized or helpful, if at all. So feedback is always appreciated.

Because there are a number of professionals involved in this forum, we sometimes tend to look at situations from a different perspective than the average homeowner/hobby gardener. A more critical design eye, as it were. And we often seem to focus on 'process' rather than result....if you spend enough time in this activity, you'll find that following a logical design process will most often end up in a very successful result. This is not intended to be unhelpful or discouraging but hopefully to get you to see things from a different viewpoint. We may sometimes be quick to point out major flaws or design faux pas but it is all done in the poster's best interest and shouldn't be taken personally.

We like to help, really :-)

Thanks so much for your encouragement! I was about to post my questions on soil testing and then I realized that there is an entire forum devoted to soil. I have so much to learn. In any case, once we get our soil testing issues resolved (needing to find a local (affordable) soil testing place as apparently CA county extensions don't do it), I'll be back to ask my berm questions.
Thanks again!

If you only want to test the acidity of the soil it is quite simple and you can buy a kit to do it yourself. I am not sure how important others here think a soil test is but, unless you have some specific plants in mind with difficult pH requirements, which I would advise against for a beginner, I think shade, zone and moisture are more important for plant choice. No matter what the situation I can almost guarantee that any soil will be lacking in humus so you will have to attend to this and check the pH (acidity) again afterward.

pH testing can be easily done with a kit from a big-box store or nursery.

Ca. being a premier agricultural state, also has lots of good agricultural labs. You'll get more information about your soil (for a price) then you may need or want to know!

I'm going to agree with Ink again :-) For a purely ornamental landscape, I don't think soil testing is very necessary. In my 30 or so years in this business, I've only tested my own soils once and that was for a college class project :-) It does help to know something about what constitutes a "good" soil however and the textural composition of your own so you know how to amend. It's a little bit different case if you are focusing on edibles and if you plan on those, I would make the effort to have a professional test done.

Yes, it does help to to know soil pH but since most plants tolerate a rather wide range of pH, even that is not overly critical. And testing for pH is something that can be easily done yourself with a home testing kit and distilled (not tap) water. Being located in SoCal, I'd expect your indigenous soils to be neutral to slightly alkaline, as is your irrigation water, so if you are interested in growing ericaceous or acid loving plants, you will need to do some adjusting on both parts. If the bulk of what you will be planting are California native plants, then you should be in pretty good shape already.

If you need to import soil (for the berm), I definitely wouldn't bother with a test. Bulk soil providers generally offer a satisfactorily amended, pH balanced soil mix. If you are using just existing soil, you will probably need to amend with some sort of compost or other organic matter both to loosen the soil, improve drainage or water retention and to bump up fertility. Amending with organic matter will tend to draw the soil pH closer to neutral also, which is close to ideal. If you need to amend, make sure you do so over the entire planting area, not just individual planting holes.

As to whether or not you need to kill off the lawn before you construct a berm, that depends on how large/deep the berm will be. I usually suggest smothering the grass with several layers of damp newspaper first, as the shallower, edge portions of the berm will allow the turfgrass to growth through unless otherwise addressed. The newspaper will biodegrade rapidly but will effectively kill most grasses and weeds underneath.

You are correct in thinking that soil is a complicated subject - there are folks that spend their entire life and careers focused on understanding soils. However, for most home gardeners, it doesn't need to be that complicated. The attached link is provided by the Iowa State extension service and while it specifically addresses Iowa soil conditions, it is a pretty good and concise overview of what most home gardeners, regardless of location, should know about basic soil 'stuff'. And relatively easy to understand :-) I'd also inquire of your county extension office as to publications they may have on improving soils as these will be more locationally appropriate.

Here is a link that might be useful: garden soil management

Such great advice already -- thank you so much. We are leaning toward testing the soil in our backyard because we really struggle to get the grass to grow (new sod 5 years ago with adequate sunlight and water), and the beds in between the grass and the fence (where we want to focus our new plantings) have grown almost nothing in the 6 years we've lived here -- 10 year old dwarf fruit trees struggle, weeds don't even take root. The front yard will take more intensive landscaping, but if we need to make significant changes to the backyard soil to help things grow, we figured that we should probably do that before we do the front yard (we have to go through the front yard to get to the back). We are actually in Northern California, about 30 miles south of San Francisco (I hope that my zone is right -- I used my zip code to get it).
Under these circumstances, would you still do a self-test for the soil, or would you have a company do it?
Thanks again!

Riskaverse, sometimes (heck, most of the time) it is difficult on this Forum to convince a questioner that there are situations where spending money may save money.

Having just read your last posting I am suggesting that you need to request a total comprehensive soil test done by a reputable CA lab for all trace minerals, etc. Not inexpensive but you will know what the soil problem is and if it is an abundance of a particular mineral this will determine your landscape approach; perhaps hardscape and raised beds rather than fighting a natural element. The inexpensive soil testing kits sold in box stores will not give you this information. A quick search for soil testing laboratories, CA will link you to some excellent ones, some involved in ecology. For your nickle, you will receive excellent advice and they will actually answer phone queries if you are a customer.

Phytotoxicity due to natural elements or spills (anyone dump motor oil in the yard? fertilizer burn?) may be one cause of the barren landscape, but what about cultivation practices or environmental factors like shade, plant selection, in-appropriate planting season, watering, or over-fertilizing?

OK, under the conditions you have outlined, testing DOES seem to be advised :-) Home testing for anything other than soil pH is not going to provide very accurate results, so yes, bite the bullet and have a professional test done. Our county extension service no longer provides soil tests either but they do offer referrals to various local and national testing labs - no doubt your extension office can provide the same. They will also coach you on the correct method of preparing appropriate soil samples.

A couple of thoughts - basic soil testing does not include testing for contamination or hazardous wastes. If you suspect this to be a problem, you need to request specific tests that will include possible contaminates.....and the price will escalate accordingly.

It may very well be your soil is just suffering from compaction and lack of fertility -- very common in existing urban/suburban landscapes. The test will reveal current nutrient levels and obvious deficiencies/toxicities (if any), however adding amendments in the way of compost or other organic matter is a far better way of improving soil conditions than simply applying fertilizers according to reported nutrient levels. Compost is also an excellent remediant for contaminated soils.

Here is a link that might be useful: here's one source to get you started...

So let's see if we can get those worms back into the can.

There is no way that we can solve the problem of why nothing grows, this can only be done with patience and on site all we can do is point the OP in the right direction. Gardengal has already started this process, what more should riskaverse be looking at especially if we take her moniker at face value?

It does seem a little bit of a rush to judgement to look for haz. wastes. A waste suite will easily cost you at list price >$800, and at that rate you may as well just cap it with a patio or deck. Depending on the age of your house the chance of a Love canal in your backyard is remote. You can have contaminants in your yard that present an exposure risk but still not be be toxic to ecological receptors.

What about neighboring plants that exhibit toxic effects to their neighbors like black walnut or a former driveway?

Hey now let's spend the OP's money on some landscaping instead of testing!!

If you have the property that would be helpful.

Again, great questions. I don't think that we are at great risk for hazardous waste contamination so we'll hold off on that, but there does seem to be some consensus for a professional soil test. We contacted the local native plant nursery we'll be using for most of the plants and they recommended Perry Lab (see the link). They seem to be much more expensive than out-of-state testing like UMass or UWisconsin, so we'll see if we can't find local, reputable and a bit more affordable. Someone from soil suggested contacting the UC Extensions for more affordable recommendations. Would you recommend local but expensive over out-of-state but cheaper (assuming that quality was the same)?

In terms of other plants creating the problem, behind the fence (in a neighboring school yard) we have redwoods (20 ft away) and Live Oak (I think I've got the name right -- 50 ft away). Fortunately, we don't get much redwood debris, but we do get a lot oak leaves. From installing french drains around the house, we know that we've got a very clay-y soil, but I don't know much more than that. The landscape designer that we hired 3 years ago said that we shouldn't have problems growing things in these locations (as opposed to other parts of the yard that have tremendous amounts of shade). We've just been surprised at the struggle to grown things in the last 3 years and so we thought a test would be a good idea.

And yes, I am very cautious, but my DH is very optimistic -- we make a complementary pair.

Thanks again!

Here is a link that might be useful: Perry Lab

I'd suggest that your problems getting things to grow well could just as easily be from lack of understanding of proper watering with your soil type, and root competition from neighboring trees like the Redwoods and Live Oaks. Root competition from large trees can suck up all the available water, and you may also be dealing with heavily compacted clay soils that don't permit deep water penetration without really running the irrigation system for much longer periods than you have probably been doing. Lack of sun from trees casting shade can also be a limiting factor in getting reasonable growth.

You probably never thought to use a soil probe to test how deeply the soil was getting wet in various parts of your garden, but I am willing to go out on a limb and bet that you weren't watering long enough to get water deeper to the roots. This time of year with the rains we have already had, you should find that a 12 inch depth soil probe should find the soil moist all the way down to 12 inches deep, but just a few weeks earlier I was doing a landscape install in Atherton with clay soils under large Deodar Cedars and Coast Redwoods, and the soil wasn't even moist more than 2 inches deep, and we had already had several good rains.

I seldom do soils testing for new garden designs myself, as I find that adding organic mulches or compost in bulk at the time of planting, timing the irrigation sufficient to know that you are helping plants root deeply, and adding additional compost as mulch at least every other year for the first 6 years will go a long ways to creating good fertile soil.

If you are thinking primarily of planting California native plants, make sure that you have them in the proper sun/shade exposures for your location, and you might want to consider installing an automatic drip irrigation for watering rather than relying on overhead spray. In most SF Bay Area gardens that I design, especially with clay soils and summers that don't get much above 75/80F on occasion, timing drip irrigation for 20 to 30 minute cycles twice a week is usually enough to get new plants established.

As to the lawn, you might find it useful to have it aerated with a coring machine, and topdress the lawn with a sandy loam topsoil to improve water penetration and add organic content. Check with a soil probe after the rainy season to see how long you need to water to get the soil wet to at least a 6 inch depth; it may require multiple cycles in one day to just the point of run-off, with a wait time between cycles to get enough water applied to a deeper level.

Post some pictures of the areas involved if you want more specific advice, but I am willing to bet that your issues with poor growth are more linked to improper irrigation technique, no use of compost/mulches to improve fertility and hold onto moisture, and not watering long enough to get water deep enough to encourage deep rooting. The neighbor's trees may also be stealing more water than you imagine, and in these areas you might think of planting more drought and shade tolerant plants that can effectively take the shade and root competition and still look good.

I don't think a soils test is going to help you in any significant way, and I'd put my money into composting/mulching and adjusting your irrigation system.

Go cheap on the testing and more on the drip irrigation and soil amendments. Also let in more light and consider raised beds if the clay is a drainage issue for your area.
Other than that good luck with your endeavors!

Bahia's queries are on target,such as, what else is in your yard or nearby, and in addition--this may seem too obvious-- but when you jam a spade into these various areas, what do you get? Do you turn over a pile of dark rich crumbly soil, or do your teeth jar out of your head, or is it very sandy? Things like that.

I'm not saying you do or don't need soil testing, but as usual on the forum, the "stuff won't grow here" raises a host of questions about things that, if ruled in or out as issues, might give some direction. Kinda making the point about the difference between "soil testing" which in its simplest form is that a pint or whatever of dirt is sent off for testing, vs. backing up to be sure there's some "site analysis."

Another DIY thing would be to ask around the neighbourhood for some history of the land before your house was built on it. The barely covered foundations of an old barn for instance would not make for fertile land, I have uncovered hidden treasure quite a few times over the years. I found a cement mixer in the backyard of a new development and a parking lot under six inches of top soil in a supermarket planting where nothing would grow. To add to bahia's "soil probe" idea, you could take a long crow bar and drive it into the ground to see if there is anything solid down there. First do the detective work then the exploration.

The downplaying being done here of the importance of the mineral content of soil to plant selection and success is wrong. Soil types and nitrogen levels present on an undeveloped site can even be predicted by observing which native plants are present.

But NOTHING is growing bboy, so what can you conclude from that with any accuracy?

My first suspect is the redwood. We don't have enough information here to be able to conclude much. Certainly can't say what to do with any assurance of it being well-targeted.

Let's return to the original post. We have two knowns:

1. There is a plan for this property prepared by a native plants designer. When speaking of implementing this plan..."Our first task is to do soil testing where nothing seems to grow." Did the designer make this suggestion perhaps based on a visual observation of the property and surrounds? An answer to this question would be helpful.

2. Grass grows in the front yard."....do we need to kill the grass before installing a berm?" Reading between the lines it appears that the front yard situation is fairly good either because of soil condition or watering. It would be helpful if the OP gave us a clue on how much the front yard is watered.

We really have not received any of the designer's thoughts on this property and lack of rear yard vegetation although something must have been said addressing the situation.

A dearth of details and a breadth of speculation! We all love a mystery, but it all hinges on lay observations. If there is truley absolutely nothing growing in this area, then adding in or making sure total organic carbon (TOC) is added to your analytical suite, if that is still your chosen path, is definetly a must.

When I put in a sand base for my girls swingset (about 1.5 feet!), absolutely nothing grew in that area. Over the last 4 years with the build up of TOC in the sand seeds were able to set and there are weeds (very sparsely vegetated about 1-weed per 5 sq foot)now. Maybe this will help you.

Explain the redwood as suspect bboy, is it because of the root span? Remember that now we have gone beyond the scope of the original question. It does seem likely that there is something in the ground that a soil test alone may not uncover doesn't it or have I been watching too much CSI?

Bare ground is usual under low-branching conifers in particular.

I think we need a photo. RiskAverse, any chance of that? You'd need to load it into a photobucket account and post the HTML tag here.

KarinL

I'm not a landscaper, just a homeowner and long time gardener. I have read over all the posts here.

I'll tell you our experience with clay soil.When we first moved into this house, because we had a very large yard we wanted a vegetable garden. My husband bought a tiller and the first pass barely scraped the ground. It took a lot of tilling but he finally got it loosened up enough to plant a garden. We had and usually have adequite rainfall so that very little watering is necessary. What a miserable failure the garden was that year. The carrots grew nothing but tops and everythings else didn't grow or didn't produce.
We had a friend who was sick and couldn't take care of his yard with multi trees. He had a mulcher that ground up leaves. We gathered all his leaves and put them on the garden, ran the lawn mower over ours and offered to do others lawns. We had a good layer over the garden. We composted what we could and brought in a little top soil the next spring.
That years garden was a bit better and it has gotten better and better over the years as we added more and more organic matter.
We found out later that our lot was part of a top soil farm and all the top soil was removed. That is why we ended up with pure clay.
One thing you mentioned that no one else has addressed is the oak leaves. Oak leaves add acidity to the soil. I wouldn't doubt that your soil could use some agricultural lime to counteract that acidity.
Good luck with your landscaping. You are getting some good advice

Bboy is on to something. Large growing conifers like the redwoods have huge, spreading root systems with a plethora of fine surface feeder roots that tend to outcompete most other plants for soil moisture and nutrients. Plus as stated, the area under the canopy stays dry - rain doesn't penetrate down through the branches easily - and often dark. We see the same thing here with our large native conifers like the Doug firs and western red cedars. This makes a pretty inhospitable growing environment for the majority of plants. Unless one provides the necessary extras to make it work - additional soil, a regular source of nutrients, consistent irrigation and an appropriate plant selection.

Redwoods of any size no more than 20' away could certainly have that effect.

Not to doubt what the OP is stating, but some part of the story is missing. When it is stated that the 10 year old fruit trees barely grow in the back yard, and no weeds even take root, yet the back yard's sod lawn of 5 years is getting sufficient light and water, yet no mention of whether things are being fertilized, or how often and for what duration the irrigation is applied.

If there was a landscape designer involved initially, was there any existing landscaping at that point to judge how things were growing? It is all conjecture without photos, more information on cultural practices of irrigation and fertilizing, whether the shrub borders at fence/back lawn receive sufficient light, and whether the OP's have done any digging in the soil to see if it is full of redwood tree roots.

In my experience gardening with Coast Redwoods, they will actively seek out irrigated areas at some distance if the area where they are planted is receiving less irrigation than your backyard. On the other hand, unless the bare soil in question is covered so deeply with accumulated debris from redwoods/oaks that there isn't really bare soil, there will be weeds growing, especially with the start of the rainy season.

I am assuming that this house is not brand new, but is located within an existing residential subdivision? Or is it a newer building site where the existing grades were radically modified, top soil might either have been entirely scraped away, or heavy equipment might have so compacted the soil that water penetration and drainage is greatly impaired?

These are all questions needing answers that might more directly impact your situation than determining your soil fertility and ph. A soils test is not going to give you answers to the above questions, which may be the more important reasons why you are having problems. If your original landscape designer is still around, and is familiar with your neighborhood and has a successful track record of addressing such problem gardens in the past, I would certainly get him/her back for a visit. You need someone is familiar with your area and area's history if you don't know the situation yourself, and who can do some detective work to sort out why you are having so many problems.

The information I am passing on to you are all the sorts of things I have come across as potential reasons for gardening failure with other clients here in the San Francisco Bay Area. You might get clearer results if you approached this as a detective and eliminated them as factors one by one.

Again, a good display of pictures of your problem areas, further elaboration of aspect and extent of cast shadows from trees on the adjoining school site, and a better explanation of the deeply shaded areas you also say you have in the yard.

Well neglect now seems to be going up to the top of my list of reasons. A very good list for others to consider at any rate.

Hi All,

My DW, who started this thread, has been asking me for two weeks to answer your questions. So I apologize for the delay and we very much appreciate your help. Below are two pictures from this morning. We've had over four inches of rain this week, and we're getting a brief respite today. So if the yard looks wet in the picture that is why.

To orient you, the back fence, from right to left, runs almost due north. We have a single story house and the lawn in the picture gets considerable sunlight during the summer.

Let me give a little history of what I did to the backyard and then I'd love your advice about best next steps. In July 2005, I rented a rototiller and rototilled the backyard, except for where there were existing plants. I added some topsoil and ~20lbs of organic fertilizer. I installed irrigation in three zones. One zone is a drip system and the other two zones have rotating spray heads. If I had it to do over again, I would add a third spray head zone to get more uniform irrigation coverage. I will probably do that in this landscaping project. I then installed sod. The grass looked great the rest of that summer. Our only challenge was raccoons who kept rolling the sod to get the grubs. I put mulch around the fruit trees along the back fence and our (sad looking) orange tree.

Each year since then the grass has increasingly struggled to grow. The first year, I bought more organic fertilizer and the grass responded well to that. I recall the fertilizer was about $50, so I bought a bag of non-organic fertilizer. I wish I hadn't bought the stuff-- the grass doesn't seem to respond to it and I feel terrible that I am using a petroleum based product.

A few years ago, we fixed our brick patio and for about a week we stored bricks on a patch of the grass. The grass in that patch hated that and has never forgiven me for it.

This last year, we had the irrigation system running 4x a week for 20 minutes a zone. I think I mowed the grass twice all summer-- it was growing that slowly and it looked unhealthy. It could be a combination of compacted clay soil, poor soil nutrients, not enough water, and no aeration. I'm not really sure. Our poor orange tree is very sad looking and each year does its best to die. So the combo of the dying orange tree and the grass, which responds to some types of fertilizer, makes me think it is a soil nutrient problem. But I could be way off.

So when my DW and I decided to landscape the yard, I said we need to figure out the soil because I don't want to invest in plants and watch them die.

Your advice is much appreciated. I clearly need to adjust the sprinkler heads which are making patterns on my fence :) The area that struggles the most is along the back fence between the trees-- I didn't rototill or amend the soil there.

{{gwi:7983}}

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Sorry you've done a lot of work and a bit of expense and still aren't happy with your yard. I'm not a landscaper altho have a lot of homeowner experience so my advice is from a different perspective. I hope you get the advice you are looking for here but advise you to also look at other forums especially the Soil forum and those that are about the style of garden you prefer.

IMO one of the problems with this area is that large tree which is taking a lot of water and nutrients out of your soil and will continue to do so. There are ways to mitigate this without removing the tree which appears to belong to your neighbor.

If you are interested in organic gardening there is lots of info and help on the Soil forum as well as the Organic Gardening one.

Without saying more I'd like to ask what your vision for this area is - the style of garden you like and how much maintenance you are willing to spend. You are almost 5 years into your plan and have done an irrigation system so I'm wondering how much you are willing to change. Usually one makes the landscape plan first then installs the irrigation to suit.

Just a quick follow-up. We installed the grass to be family friendly for our two young kids. We didn't give the overall design much thought then. We now have a design that includes a lot of CA natives, with plants suited to handle the redwood behind us and the oak trees on the south side. We are ready to make a more significant investment now, but want to make sure that we address the soil stuff. Thanks.

What a difference a picture makes. I would hazard a guess (bboy ?) that the problem you have with the "soil stuff' as you call it is due to roots. Is it possible that roots caused that crack in the concrete patio? If you improve the soil, with or without that soil test, those roots will have a birthday celebration. If you are indeed ready to make a significant investment you need a designer who thinks outside the box. There is not a law that says a lawn needs a necklace of plant stuff.

I agree with "it's not the soil but the trees." True too that any water or nutrients you put on that lawn is/are feeding the trees.

Watch trees this size in nature and you will see that virtually nothing grows around them. When smaller they were of course surrounded by other plants and other trees, but one tree eventually outcompetes all the others... for water, nutrients, sunlight. Your neighbour's trees are outcompeting your lawn, plain and simple.

I have lived next door to similar trees and tried to have a garden, and it nearly cost me my sanity (and it certainly cost me my relationship with the people who owned the tree). The trees never stop growing; they have no awareness of the property line, nor indeed of any structures such as fences, houses, or sidewalks. If the urban environment that you own is to be maintained, those trees have to go. Unless, of course, you are willing to cede your yard to the tree. I was, for a while, because the shade was marvellous. But after a while, the compromises are too much and the only answer is for the tree to go. For you, it all depends on whether what is basically a forest floor will do for you for a yard. An expanding forest floor, because even if you garden outside the root zone, that zone grows every year.

A forest floor garden has its charms, of course, and you can grow some things there. But it's not lawn territory, and it doesn't fit a lot of people's idea of front landscaping, which was also mentioned in your DW's OP. In addition, what you do in your garden can affect the stability of the tree.

If I were you I would just let the lawn do what it will with the irrigation you have in place, and start talking to your neighbour about a 5-year tree removal plan. Maybe removing one tree in two years, planting a new tree there, and then removing the other in 5 years. In my case, we paid half the cost of removal and offered to buy a replacement tree. Mind you, it didn't go anywhere until they sold the property and we were dealing with new owners, but we would have joined the legions of others who have gone to court over trees if it hadn't gone ahead. I hope you have more reasonable neighbours.

KarinL

oxygen deficiency

A tall fescue lawn in a northern California winter is going to look a bit bedraggled, and hardly grow much. The thinning of the grass is probably due to lack of sufficient irrigation suitable for best growth in the hotter months, in combination with insufficient top soil with organic content added before you sodded it, and not fertilizing often enough to encourage better health and growth of grass. How many inches of topsoil did you add before rototilling, and how often and which months do you fertilize, and what is the N-P-K ratio of the fertilizer you are using? As to whether 20 minutes of spray irrigation is sufficient for a lawn in northern California conditions, especially if applied 4 times a week on a flat site, if anything this is overwatering, even with heavy root competition from the redwoods and oaks across the fence.

It looks to me that you need to build up soil fertility in both the lawn, and particularly for the citrus tree, which shows signs of nitrogen deficiency in particular, and is probably also not getting water in summer sufficient to get rooting deeper. Just adding a mulch with chicken manure in it, or mushroom compost or similar as a 4 inch mulch, ought to help the citrus tremendously. I'd also suggest adding some time release fertilizer such as osmocote and work into the soil in March, for longer term/slow release of nutrients, and check with a soil auger how deep your irrigation is penetrating with the irrigation you are giving it.

The lawn can also be top dressed with a light screened mulch after having it aerated with a core type aerator, and the top dressing raked in to help fill the holes, but it might be better to simply use a sod cutter to skim it all off, add a healthy 6 inches of organic compost to the lawn area, and resod. Lawns here typically benefit from several fertilizing periods, at least once in mid spring and again in summer and early fall, or refer to the web site referred to previously for recommendations. You might also consider using a mulching lawn mower that chops up the grass blades so that they return to the soil, and preserve the nitrogen that is otherwise thrown away with each clipping.

As to Ink's complaint about "cliche" eyebrow plantings around the edge of the lawn, I don't think you are really looking at other solutions if you mean to keep the existing lawn size and layout, but I do second Ink's opinion that the narrowness of the planting areas against the fence is rather dull and static. Planting of vines to cover the fence, and widening the borders to allow at least some layering of shrubs and herbaceous plantings is entirely possible if borders were widened to minimum 4 to 8 feet wide if you can give up some lawn space.

The proximity of those large redwoods and oaks across your fence is definitely tapping into the irrigation you are supplying. The vigor of the trees, and even some of the plants in your own backyard indicates to me that yours isn't so much a soil fertility problem, as it is poorly timed fertilizing and no ongoing attempts to increase organic content of your clay soils via mulching with compost, as well as not checking to see if your irrigation schedule is adequately wetting the soil to sufficient depth to encourage better growth and plant health under drought/heat stress of summer.

Having dealt with many California gardens under or adjacent to redwoods and live oaks, the soil ph is unlikely to be the problem, as I am willing to bet your soil is only mildly acidic or even close to neutral. We just don't have moist enough conditions year round to create acidic soils from dropped leaves in a suburban garden setting. The problem is the root competition of water, and any plantings you add will greatly benefit from adding tons of organic component, mulching with compost on a yearly basis, selecting plants that tolerate root competition with redwood tree roots, shade and constant debris, and closely monitoring your irrigation cycles to see that the plants are getting what they need.

Beyond a soils test and a landscape design, you need some help from a good horticulturist who can advise you what you are doing wrong/right in your particular circumstances. I'd also make darn sure the natives you have on your plans are compatible with redwood tree competition, as well as potential overspray from the lawn irrigation. Fertilizing more frequently for plantings below/adjacent redwoods is extremely helpful, and if you prefer the organic route, stick with a good organic mulch that has some manure in it, and reapply a couple of inches every year.

(DH here again)

Thanks a lot for the comments. I especially appreciate all of your thoughts, Bahia. I probably only added 1-2 inches of top soil-- 2-3 cubic yards of top soil looks like a lot until you start spreading it out. We probably need to scrap the current grass-- amend the soil with considerably more top soil and mulch. Too bad our goal wasnt mushrooms because we have a bumper crop after this last week of rain. (perhaps the mushrooms also indicates a problem)

Our new plan was designed by a native specialist. She hated our narrow edges (the necklace) and has us expanding those aisles so that we can include layering with shrubs and taller grasses. I think all of her specified plants are okay with oak leaves. Despite the location of that redwood, which is in the back corner of an elementary school, we have very few redwood needles because the prevailing wind drops them in the school property and another neighbors yard. Whenever I rake, I have bins of oak leaves and barely any redwood needles.

Bahia, you mentioned cutting the sod out. Is that preferable to rototilling it under? It seems much easier to rototill the whole thing, add 6-8 of top soil and go from there.

riskaverse said:

ââ¦some sections where nothing seems to growâ

ââ¦we really struggle to get the grass to grow (new sod 5 years ago with adequate sunlight and water), and the beds in between the grass and the fence (where we want to focus our new plantings) have grown almost nothing in the 6 years we've lived here -- 10 year old dwarf fruit trees struggle, weeds don't even take root.â

ââ¦we know that we've got a very clay-y soilâ

âWe've just been surprised at the struggle to grown things in the last 3 years â¦â

â ⦠July 2005 â¦.rototilled â¦20lbs of organic fertilizer ⦠irrigation ⦠installed sodâ

âEach year since then the grass has increasingly struggled to grow.â

From the above and info from the photo, the site is relatively flat, with soil the homeowner refers to as clay-y, and a general failure of a wide range of plants to thrive.

I said the problem was oxygen deficiency. I will now elaborate on how I came to that conclusion.

Clearly there is an element that is a limiting factor to plant vigor here. Roots from the large trees near the property could be a problem, and almost certainly will be a problem once the limiting factor is corrected. But if root competition is the primary cause, I would expect to see a notable gradient of the severity across the site, relative to the distance from the trees. The photo does not bear this out.

Lack of sunlight can be a limiting factor. But here again, the photo fails to show a gradient of severity from the sunnier areas to that of shade.

Lack of water can be a limiting factor but the failure of the plants to respond to irrigation indicates this not to be the case here.

Soil that has one or more mineral nutrients out of optimum can limit plant vigor. But for any such case there is usually a marked difference in the way different plant families respond to the single deficiency. Here we have lawn, shrubs, trees, and bedding plants that all seem to suffer a like failure to thrive. I conclude that a mineral deficiency is not the primary cause.

Nitrogen levels in the soil often impact growth rates. But the optimum nitrogen level varies greatly from one plant type to another. Heavy feeders like lawns, vegetables, many bedding plants, and some shrubs can be severely impacted, while light feeders such as many trees, most weeds, and some shrubs will show a normal plant growth. From the photo and description, this doesnât seem to be the case.

Plants also vary greatly in the ability to survive a sudden and severe oxygen deficiency. Many plant types are killed outright while others will survive. But a sustained moderate oxygen deficiency seldom kills plants directly. The symptoms are slow growth, reduced seed and fruit production, lack of vigor, and increased susceptibility to disease. The symptoms will be observed in almost all plants, even those that can survive a severe deficiency.

Sustained moderate oxygen deficiency is associated with the following; flat terrain, over abundance of water, clay, and compacted silt soils. To some extent all seem to be present in this landscape.

Oxygen levels in the soil are a function of the rate of oxygen use combined with the rate of oxygen diffusion through the soil from the surface. In areas of cold winters, the rate of oxygen use is greatly diminished with the reduction of the respiration of soil biota and the soil gets a chance to be recharged with oxygen. âZone 10, CAâ isnât going to see much of this effect.

Oxygen diffusion through the soil is complicated and based on the physical properties of the soil. A homeowner has no way to measure oxygen levels, but there is a strong correlation of diffusion with that of soil permeability. Assessment of oxygen deficiency can be had by studying the rate that the soil can absorb water and a comparison of plant vigor where the native condition is contrasted with soil that has been modified for permeability only.

Fluffing the soil with rototilling can cause a temporary increase in soil permeability. The only noted increase in plant vigor was associated with this practice. While fluffing the soil can be palliative for annual plants, a more permanent fix is needed for lawns, trees, and shrubs.

Without a precise knowledge of the soil make up and the potential for sloped grading, there is little that I can recommend. But I can say that it is usually a bad mistake to mix topsoil and clay.

While I would agree that mixing in insufficient quantities of topsoil with organic component with clay is ineffective in increasing aeration and water permeability, doing it with sufficient volume relative to the depth being rototilled can make a huge difference. If you are blending the two to a 6 to 8 inch depth, then adding 4 to 6 inches of an organic compost and topsoil with lots of humus is not too much.

I recommended skimming off the existing grass because it may also have a lot of weeds by this point, but rototilling it along with additional compost/topsoil isn't necessarily a bad thing, when it looks as sparse as yours does.

You might also consider mounding of planting areas peripheral to the lawn, which will both help with aeration/drainage and give the yard more interest. I've also found that simply topdressing existing clay with 4 inches of compost, and only blending where new plants will go, in addition to planting on slightly elevated mounds makes a huge difference with plant growth. It is the lazy way of amending soil, and if the mulching with compost is repeated annually for the first five years, it will make a huge difference in both soil structure and fertility over time. The earthworms and soil fungi and bacteria will do all the work, and this replicates the natural process of dead leaves turning to humus at the soil surface.

The other route that could be taken here is to design with plants that don't need fertile soils and handle poor draining clay soils, and I see a few plants like the Agapanthus and the one deciduous fruit tree near the rear fence close to the redwood tree seem to show no signs of suffering or poor growth. The fact that the trees are thriving next door shows that there is no real problem with the natural clay soils in the area, they are thriving. This makes it more obvious that it isn't so much the soil itself, as it is with how the garden is being maintained.

Bottom line, add significantly more compost/topsoil by volume before redoing the lawn, at least 50% by volume, and as you are widening the "necklace" of planting between lawn and fences, mound these areas slightly,(even 4 inches at center ridge relative to edges can help), and also heavily amend or heavily mulch with compost, and repeat annually.

As to irrigation timing, get yourself a soil probe, or dig with a spade to determine how long you have to water to get water down a foot deep, and aim for that amount. If you are planting mostly California natives, late fall is the ideal time to get these into the ground and use the least irrigation and promote deepest rooting, but avoid working in clay soils when they are so wet as to be sticky on tools, as you will compact the soil structure as well as increase the work involved.

Other things to consider; mulch that citrus tree heavily, and give it a citrus fertilizer as recommended, and water more regularly if you want good juicy fruit. It might even be better if you simply removed this struggling specimen, mounded up or created a raised planter in that same area, amended the soil heavily, and replanted with a Citrus variety that you most like. Citrus in general are heavy feeders, and will show their distress with yellowed leaves and poor growth.

Looking at the trees growing beyond your fence, there is no reason to believe that your backyard has any specific problems that can't be improved by adding more organic content to your soil over time, and adjusting your irrigation practices to match the needs of the plants and vary the application rates by season as they change. Four times a week for 20 minutes may be a summer rate, but isn't going to be required with cooler temps and shorter days of spring and fall, and you may be able to shut the system off entirely during the winter rainy period.

PLS, good analysis and I think both yours and Bahia's advice has definite merit. I'd only argue that there is a possibility from the photo that there is worsening of the grass toward the fence, possibly due to the tree(s), though it's hard to tell for sure.

If it's an elementary school and they have the whole schoolyard to work with, they should be advised to plant some new trees now with a view to being prepared to remove these sometime. They may not be causing your problem now, but they will cause a future owner of your home problems at some point and so a tree succession plan embarked on now would be a good thing. If the school has some wise teachers, they can use the process as a way to teach about the responsibilities of tree ownership and the cycling of forests etc.

KarinL

Help! Although I know a little about drought tolerant plants, I know nothing about landscape design. Are there any free or low cost public services that could help us draw up a low water use landscape design/plan for the bare front and back yards? Landscape Interns perhaps? Someone who needs to do a drought tolerant demonstration project????

We are broke from essential repair expenses for a badly neglected West L.A. house that my husband inherited. Now we do not have any money to hire a landscape designer for a low water use landscape. Curb appeal is crucial, but avoiding being regarded as the neighborhood eyesore is also important.

Also, any good sources for plants where we could get price breaks? We will have to buy plant material as we go along.

Any advice would be greatly appreciated. Thanks.

I'd make the beds bigger around the circumference and plant TALL "garden thugs" at the back. Aggressive plants have a place--this is what they shine. Don't kill yourself trying to grow fiddly plants here!

Reysuela said what I was thinking - aggressive plants along the fence closest to the tree. Just try to look for plants that are aggressive without spreading by seeds (keeps the problem in check a little better).

Native pachysandra (allegheny spurge) spreads mostly through it's roots/rhizomes. Avoid the Japanese pachysandra, though.

If you build up the soil over the tree roots you will likely harm the tree. Normally I'd say don't do that. In this case .... it may not be a bad idea (wink wink, nudge nudge).

> Just try to look for plants that are aggressive without spreading by seeds (keeps the problem in check a little better)

If they are seed-spreading, it's okay as long as they are also TALL and so a lawn mower kills them!