Are the amounts of dolomite and other fertilizers arbitrary? Because dolomite doesn't come in a 'low calcium' brand....and dolomitic limestone contains magnesium already.

Do you know what the pH of your finished product will be? That's a lot of lime if you are just winging it. What is the pH of the existing soil? That makes a big difference.

And that seems like a lot of water soluble fertilizer. Are you planning on blending it, dry, with your mix? You cannot substitute a 13-0-3 fertilizer with a soluble 20-20-20.

I'd strongly suggest that you find a good granulated fertilizer with minor elements included and apply it according to label instructions.

The amount of peat you're considering (2 cups) is negligible. Leave it out. Pine bark fines make a great amendment on their own. I would also leave out the vermiculite and replace it (if you must with perlite. The former collapses very rapidly, turning into mush instead of providing the porosity I assume you're looking for.

I really don't like the idea of adding imidacloprid to an area full of flowering plants considering the problems it causes for nectar and pollen feeding creatures. But that's me.

yes, the 20-20-20 is a starter fert, I'm amending it with a slow release as well, not noted but recommended by others. I'm not using a lot of peet because of the soil and the vermiculite is being removed. I spoke with fafard and they said there 51 mix is a good replacement for what i'm suggesting because 52L doesn't have vermiculite. i don't need it anyways with the soil. i'm working on getting ph, from the lab. soil here is typically very acidic and needs lime to balance. can axe the imidacloprid not a big deal

thanks for the input.

double post

This post was edited by john_hammer on Mon, Aug 11, 14 at 13:39

Well! I should have suggested Fafard right off the bat! I'm a huge fan of both mixes you've mentioned....they are what I use and have used for over two decades, including many professional years.. I prefer the 52 because the bark is a little coarser, but there's not that much difference.

You could even consider their Nursery Mix for your purpose. It's a wonderful amendment, though I use it in my containers.

How easy can that be? The Fafard products are also pH adjusted with
Dolomitic lime, which solves that issue for you, too.

Good for you, John!

thanks! I'm talking with Dennis out here in Mass. from sungro regarding the mix and he said because of the topsoil I don't need the vermiculite which makes sense. Our consensus was solidification of a pine bark based mix because the water retention of a peet moss mix is redundant and drainage. Like you, he and the contract and I agreed that their 20-20-20 won't last long and contractor to add slow release. Prides corners (supplier of plants) uses a pine bark albeit lower percentage, for their nursery mix and waters 30mins everyday.... we'll have to ween them off this schedule during the fall... hoping to be at once per week by late sept.

thanks again.

Why add sulfur? As far as I know it's mainly to lower pH, but you are also adding lime. One or the other, not both, depending on what the pH is, no?

Is the mag sulfate (Epsom Salt) based on a known Mg deficiency?

I'm no expert but it seems like tilling in a bunch of compost would be just as good as mixing up a 'potting mix' and tilling it into the topsoil. At least that's the conventional wisdom around here: use potting mix for pots, and compost for soil. If I was doing a big project like that I'd get a truckload of compost from a local source and call it good. It would likely be much cheaper. JMHO.

Particularly since about half of those plants could be impolitely referred to as 'weeds'. Give them a too rich, too light soil and they will run rampant over anything else in their way.

Weeds clumped together can look quite nice... and I'm fine with whatever takes over, there is a short term plan and long term plan embedded with this design... the primary goal is mass planting and grouping salt tolerant and drought tolerant plants together.

what are you considering weeds.... I mean thats a pretty complete blooming list... i spent a lot of time researching plants for those conditions.

Drought tolerance is pretty much a non-issue. You have hinted that you are in Massachusetts, and unless there is a rainproof border over there, it gets a fair amount of water falling from the sky. A bigger concern is that a lot of the plants usually described as 'drought tolerant' can't handle the amount of rain that falls during a wet year. I'm not familiar with all the plants on your list, but almost all penstemons have upper limits, and rudbeckias can look pretty awful some years.

What I am referring to as 'weeds' are plants that have wandered into unamended beds on their own, and proceeded to push out everything else. Specifically GOLDENROD! What you are going to have in three years is a mass of goldenrod with some asters mixed in. And that is if you don't amend the bed. My mind is really struggling with the idea of how quickly it will spread if given a nice, cushy home. Is it possible it could take over the whole bed in one growing season?

Sounds good, John. I think that you'll be happy with the results. I'll add that you should moniter the need for watering based on what you feel with your fingers.....rather than a schedule.

If this is a non-irrigated location, I'd skip the Clethra. That is a moisture loving plant and is unlikely to be very drought tolerant at all in full sun. In fact, even in my mild summer climate I would hesitate to recommend clethra for a full sun location even with irrigation. There are much better flowering shrubs suited to those conditions.

And I might skip the solidago and substitute an upright sedum in its place - far less likely to be such an aggressive spreader and extremely drought tolerant. Are there any height issues? And do you care what this round-about looks like in winter?

Fafard/sungro recommended their 52... see how it goes

The comments about the goldenrod are well taken, although it's 4% of the entire planting plan.... I have 1,040 plants within 1,250sf or 12" o.c. so losing the golden rod isn't the end of the world. I'm over planting intentionally to shade the ground and avoid weeds, let the strongest survive, mass planting. For what it's worth, there's a 6' sod buffer between this inner circle and the curb.

I have 250 of both side oats and little bluestem so winter color should be good... everything else will be dead but the grasses will stick up nicely until they are crushed with piles of snow.

the daisies look nice up here, very common. the goldenrod could be a concern though and they are intentionally planted near the center under a common lilac.

thanks for the comments

Perhaps there is a difference between drought-tolerant and plants that can survive the expected climate w/o being watered. I think the latter is what you're going for, correct?

The grasses can't stay up because the easiest way to control woody weeds is to mow (brushhog) the area once or twice a year. If you are planning on doing regular garden maintenance on this garden, that isn't an issue. But I'm getting the idea you are after something 'natural'. This isn't it. The 'strongest' are going to be sumac, brambles, and whatever the local squirrels think should be growing there. My squirrels like cherries, so I end up pulling a lot of them.

toxcrusadr:
Drought tolerant to me, means the plant material is able to live in conditions that are drier than the given climate or zone would normally provide and without irrigation tp supplement that given micro-climate. Seeing this round-about is an island in a sea of pavement I'm expecting water retention in the soil to be an issue... the only water it'll get is from rain, none from the surrounding stone under the road and therefore no ground water recharge or soil moisture retention and therefor drought condition exists.

I also have a salt problem... being in the middle of a road.

I don't understand what mad_gallica is saying but I'm not proposing a bare dirt area for whatever to grow. I'm over planted by almost a factor of 2.... since most plants grow to 2' wide and everything is going in 12" o.c. in 1 gal pots.... it's going to be difficult to get all these plants crammed into there let alone weeds. I did remove the goldenrod, that was a great suggestion even though it served a purpose.

What I am trying to say (admittedly quite badly) is that this sounds to me like a solution in search of a problem. It could simply be that it is going in a dry climate, where things work very differently than they do here, but that doesn't match the geographical references I've been able to pick up.

So for here, the average annual precipitation is a little over 44 inches. A severe drought is less than 35 inches. For comparison, Denver averages a bit more than 15 inches a year. Plants from that ecosystem struggle with the moisture levels here. Instead of being drought tolerant easy keepers, they are rot prone divas. Some people go to the effort to grow them, but it usually involves hillsides and special soil preparation for incredibly good drainage.

Then there is the local flora. What wants to be here is trees. Big trees. Neglected spaces grow trees. Abandoned parking lots will have trees growing in them, as will neglected gutters. So any weed control has to be aimed primarily at the trees (and other woody weeds). Since in most places, tree control is a de facto result of mowing, it doesn't tend to occur to people that this is a problem until they have a small maple forest growing in their pachysandra. The trees are designed to outcompete anything else.

Trees will not be permitted to grow in the center island, but I agree, natural succession in this region is forestation, and weedy maples grow in sidewalk cracks so... they'll be dealt with by the municipality for safety reasons.

dang, double post i'm good at that.

This post was edited by john_hammer on Tue, Aug 19, 14 at 15:58

Fafarad 52 mix recommended by sungro... don't need the perlite or vermiculite but I guess that's how it comes.... won't hurt anything. Tilling in slow release fert as well