How do you Modify Al's Gritty for the HOT Desert?

Suzi AKA DesertDance Zone 9bMay 31, 2010

In the thread in this forum on Smart Pots, I noticed that those with experience in hot areas say that these pots drain well with Al's Mix. Too well! They dry out in the heat FAST! I am in Zone 9b.

Cebury, Zone 9 states, and I quote, "I've got several Smart Pots as well as testing out a line of Fanntum Containers for my containerized fruit trees. I live in Central CA where the heat is crazy. However, only two of them have the gritty mix and I was betting I wouldn't make it through the summer in those. I suspect the gritty or 511 mix in a fabric container, in dry 100+ weather, will not work unless you are a watering maniac. I made it through last year in plastic containers with the gritty mix (added 20% more turface and reduced granite) but the hottest days did require container shading. Also the smallest containers, and one citrus tree where the roots were extensive and filled the container, required a cache pot or placing mulch around them. Those is my area scoff and say you *must* use peat or coir in every mix to survive the summer heat. Well I've certainly found that peat "bakes" (as does other media), when used in plastic containers in full sun. Just because a mix holds lots of water doesn't mean you can ignore root temps. There is not enough aeration in a heavy water-retentive soil in a plastic container for it to release the heat."

I plan to use root pruning pots for my containers because the roots don't circle, and the root mass is then much bigger causing the plants to grow faster.

Is there a way to modify the mix so that it still drains, but not so fast? I don't want the top to dry out, of course, and am going to put a piece of shade cloth over each container's top to shade the roots, and prevent evaporation, but I don't want my roots to dry out due to high heat and fast drainage, either, so any suggestions?

Will Cebury's solution of less gran-I-Grit, and 20% more Turface work?



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Suzi AKA DesertDance Zone 9b

The mix I need to modify is this one:
1 part uncomposted screened pine or fir bark (1/8-1/4")
1 part screened Turface
1 part crushed Gran-I-Grit (grower size) or #2 cherrystone

I wish we could edit our posts. I hate having to post again just to revise the post I just posted!

    Bookmark   May 31, 2010 at 12:08PM
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tapla (mid-MI z5b-6a)

4 parts Turface
3 parts bark
2 parts granite
1 part vermiculite

Plant a little high, and after the planting is established, mulch heavily with crushed granite.


    Bookmark   May 31, 2010 at 2:19PM
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Suzi AKA DesertDance Zone 9b

Thank you very much Al! I'll try that, and keep the thread updated. Summer just hit here (100 degrees past 3 days), and the air root pruning containers have been ordered.

I about freaked when I read Cebury's dilemma in the hot central valley, because we are a good 10% hotter here!! I knew you'd have an answer!


    Bookmark   May 31, 2010 at 4:05PM
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tapla (mid-MI z5b-6a)

You have a lot to deal with there, Suzi. Soil temps and deciding how much water retention your plants can tolerate, and how little YOU can tolerate. ;o) This is one of those cases that draws a stark line between grower convenience and what's best for the plant. Don't take that as judgmental, because it's not at all - just an observation about growing plants in general. You just happen to live in a climate where effort above and beyond what most of us have to make is required to provide the best cultural conditions. ;o)

Best luck .....

BTW - you might want to make your soil first, then take a portion of it and add the vermiculite. Put a few inches of soil w/o the vermiculite on the bottom, them add the soil WITH vermiculite to fill the rest of the container.


    Bookmark   May 31, 2010 at 5:24PM
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jojosplants(9/ Tucson, Az.)

I am in a similar area..

Al, How does crushed granite benifit as mulch compared to bark?

Were in the 100's here now..


    Bookmark   May 31, 2010 at 5:33PM
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tapla (mid-MI z5b-6a)

It reflects light which reduces heat gain, and it is also a little better at containing evaporative moisture loss. There is a small + from the added light on the lower foliage too, but it's not much of a consideration. 100s - yuk! ;o)


    Bookmark   May 31, 2010 at 10:08PM
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jojosplants(9/ Tucson, Az.)

Thanks Al~

100's aren't that bad if your a summer person.
It's a dry heat..LOL!

I like the look of bark, but will give some gravel a try.


    Bookmark   May 31, 2010 at 10:21PM
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Suzi AKA DesertDance Zone 9b

I found the pine bark fines for a great price! And same for the Vermiculite! I also found something called pumice, really cheap, and I'm wondering, maybe kick a little of that in the mix?

I know why you suggest vermiculite over perlite. Water retention! And we do need that in the desert.

I also wondered, along with JJ, why crushed granite as a mulch instead of bark?

The other dilemma is DE seems to hold more water than Turface. Should I switch to Diatomaceous Earth? I think they are about the same price. I need 11 cubic feet of whatever......


    Bookmark   May 31, 2010 at 10:53PM
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tapla (mid-MI z5b-6a)

You could do that (DE) if you want to. Be cautious though. Your soil (with xtra Turface & vermiculite) is going to hold a lot of water. You CAN over do it. What you might want to do is try some soil with the (screened) DE in it and use a wick until you see how it goes. You'll prolly have to water like heck at first, but once the roots colonize the container, things will get easier on you.

I think you know the basics & understand what's in the 'Water Movement' thread, so let that guide you .... and keep thinking aeration aeration aeration at the same time you're trying to maximize water retention.

You saw my reply to JJ - right?


    Bookmark   May 31, 2010 at 11:28PM
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Suzi AKA DesertDance Zone 9b

Thanks! I did see your reply to JJ! You were replying while I was posting, so we got crossed!

Do you have any opinions on Pumice? If so, would it compare to Grit? or to Vermiculite?


    Bookmark   June 1, 2010 at 9:38AM
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Suzi AKA DesertDance Zone 9b

Here is the reason for this thread. These are my baby cuttings.

The Children

Mostly wine grapes, and also Olives, Poms and Figs.

They all came from UC Davis at 2 different times (most on April 1), so they are about a month apart in development. They are in 2" x 2" x 10" zip set air pruned planting bands, and out of 120 spots, about 60 look like they will make it. Others are questionable. They are in 50/50 peat and perlite.

What I love about the zip set planting bands is that they are biodegradable, so I can just set the whole band into the 3 gallon container, fill with the Desert Mix that Al created, water, and not disturb one root, and the band will disintegrate. There is no bottom to the bands, so if I want, I can just pull it out, after planting!

The first ones will be transferred to 3 gallon Sunleave 6.5" x 13" x 7.5" containers, in a week or two, and put outside on a drip system. We are going to hand drill air holes in the sides of those containers. They will be protected by shade until they seem like they are happy!

If the olives live, I'll be surprised. From experience with cuttings I planted outside, I KNOW they take time!

I appreciate Al's efforts to modify, or a create, a mix for us desert rats because it's very true, we are determined to grow what we wish against all odds, and we are committed to do what we can to make it easier. Of course, the cuttings I chose are varieties that crave heat and wind, and hate cold winters! I could not do it without a DRIP system, for sure!

Next big hurdle is to find cheap bamboo stakes for each pot!

Here is a link that might be useful: Containers I Ordered for this Project

    Bookmark   June 1, 2010 at 10:16AM
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Suzi, those containers work very well and they are very inexpensive. I'm using them (although a different name brand) for many of my Blueberries and they work excellent to keep heat off the soil (within reasonable expectations). They also hold in moisture as well as the plastic. Other than the aesthetics and lack of hard sided containers, I don't see any other draw backs (so far).

I'm having so much trouble with the gritty mix now for *fruiting* crops, I was about to post a poll to see if ANYONE is using it successfully in zone 9/10 for fruiting crops. After searching the container forum and finding 2 people who were building gritty mix for fruit, they informed me (offline) they gave it up and went with regular potting soil or in-ground for fruit trees. I know the gritty mix is popular on GW but mostly for Citrus and many of the gardeners are in wet climates. Having small citrus trees with a few fruit in zone 7 is very different than a medium sized tree with loads of fruit in zone 9. Also, citrus fruit take several months to size up whereas other fruit are much quicker by at least a few months.

I started using my normal mix (1.2:1:1) for 6 genetic dwarf miniature peach trees. In the last month I've really struggled with the mix for one tree that has only 8 peaches on it. The other 5 peach trees (the same size with about same foliage) can go 2.5 days before they wilt, but the one with 8 peaches is barely making it 1 to 1.5 days -- and that is with 90F days. In the last two weeks it got warmer, so I added a lot of mulch and moved the containers so they are shaded (but the foliage isn't). I also put back on the bottom saucers to allow it to hold even more water (forcing a perched water table)! The changes helped keep the watering the same, even though it's generally 10 degrees hotter now than last month. It isn't even hot yet. Once it gets to 100F I hope I've eaten the peaches already, since I don't think any of them will go more than a day without watering.

I think my only option is to use very large containers. I'm afraid for deciduous fruit trees the appropriate watering method is feast/famine. When it's growing the fruit, it could be using up to 30x (I'm guessing here, I know Citrus need 10x) more water than it needs in winter once it drops all it's leaves. My point is drastically modifying the gritty mix for extra Turface and reduced grit for deciduous trees may cause wet feet root rot during winter. I am using a drastically modified mix for half my blueberries and so far they are doing excellent (but I haven't made it through winter yet).

As I said in the other post, I had lots of trouble keeping the nitrogen up during the flush and fruit setting period, but I ended up solving that by using CRF pellets, along with granular fert, to supplement the every week FP+Ptkt. The combination of a young fruiting tree using up so much N along with the gritty mix draining fert so quickly brought obvious signs of deficiency.

I love the idea of the gritty mix for Citrus (and it's excellent for several indoor potted plants). But even though I have 20+ Citrus containers in the mix, I do not have any that are medium sized trees producing lots of fruit. So I honestly don't know how well they will do in maturity. Maybe after I adjust the ratio for more Turface (or using vermiculite as Al suggested to you) it will be fine. I'm hoping and expecting so.

Anyway, I'm rambling here so I'll stop now. Once I've tried a few options and documented results I'll organize my evidence (and thoughts) to either come up with a solution or ask clearer questions.


    Bookmark   June 5, 2010 at 7:44AM
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Suzi AKA DesertDance Zone 9b

Interesting, Cebury! So for the citrus, to avoid root rot, maybe not so much turface? More, definitely, but less of more... :-)

Thanks for your fertilizer ideas also. Most of my containers will have grape vines. Others Olives, Pomegranates, and figs.

I don't think any of those like wet feet, but damp feet is different than WET feet, and the mix will hopefully drain well! Our winters are in the 60-80 range, so we do have warm days then also, and one or two days in the 40's.

It seems like we get more rain in August/Sept than in winter/spring because of the tropical storms.

PS! My 3 gallon containers will arrive today! YAY! Did you punch holes in yours to make them root pruning? I am going to do that with a drill about halfway up from the bottom, about an inch apart. Not big holes, just holes to let the roots prune themselves instead of circling.

    Bookmark   June 5, 2010 at 9:40AM
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Definitely using CRF pellets is a good idea -- it provides you with a "baseline" of continuous release fertilizer for your area. That way you don't have to fertilize with *every* watering the entire year. Right now HD (big box store) is eliminating their Dynamite CRF stock here in Fresno and down south. You might check out the clearance section the next time your at an HD.

About the grow bags -- there was one piece of research I reviewed and confirmed with a member of another forum that I trust that stated punching holes in any container does very little for air root pruning. The concept of air root pruning is not a gimmick, it is legit but the containers have to be specially made to force roots to grow toward to hole. When you punch a side hole into a container, many of the roots will simply "turn to avoid" the hole. In reality, the soil in front of the hole is drying out faster than the soil on the sides of the hole -- so the roots will grow toward the most favorable conditions: where air + moisture exist.

Special root pruning containers are either entirely fabric containers or (poly/plastic) mold designed with special indentations forcing (nearly) every root toward a hole. They are expensive, but the air pots you were reviewing in the other post were very reasonable for large container sizes as they can be purchased individual at retail locations.

You probably already know this since you did the research also, but supposedly the Rootmaker brand works well.

The holes however do provide added beneficial aeration to the root zone, but that's different than root pruning.

Here is a link that might be useful: Link to GW post about topic

    Bookmark   June 5, 2010 at 2:46PM
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Suzi AKA DesertDance Zone 9b

Cebury, I just wondered if you drilled holes in yours. I plan to, but not too aggressively. We need to make a trip to HD today. I ran out of Round up. There is an evil bougainvillea trying to take over my vineyard trellis, so it's days are numbered...I have a big bag of Polyon heat activated fertilizer, so I'll use that to start. I'll look for the CRF pellets on sale. Vines need stakes, so I'm also looking for some cheap, 4'tall bamboo stakes at HD.

It's 108 degrees outside today!! Summer is upon us!

Costs are interesting.

In-ground costs:

I paid for bare root vines, extra soil, the trellis and drip system and the vines were about $11.00 each, PLUS all the other stuff like stakes, fertilizer insecticide.

Container costs:
.47 each, + .25 each for the vines (price of shipping from UC Davis for cuttings), Gritty mix for the Desert, $3.00 each, a Tablespoon of Fertilizer and Dolomite, so under $4.00 each vine (or olive, pomegranate, fig) to start, plus a new drip system dedicated to them, pesticide, etc. As the years pass, they will need to be potted into bigger containers, so it will probably even out over time, and then surpass the costs of the in-ground, but it's a pretty easy pill to swallow.

Happy Planting!

    Bookmark   June 5, 2010 at 4:11PM
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I haven't drilled any holes in my grow bags, but so far I'm only using them for blueberries and they seem to be a special case for root moisture needs.

Did you get your new containers yet? Your children look great, I'm sure you'll provide them with the best care.

108! Wow we're in low to mid 90s. That extra 10% hotter in your area has a significantly more than 10% effect on the plants.

We should keep in touch, feel free to email via the forum email links.

    Bookmark   June 6, 2010 at 4:24PM
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Suzi AKA DesertDance Zone 9b

Cebury, I am trying blueberries in some containers. A dude in South Carolina assured me that his are on the vineyard drip system. They need a lot of water. So I have 3 containers on the drip system, but so far it aint pretty!! I'll probably kick the blueberries to the curb in favor of the wine grapes. It's hard to beat walmart! Blueberries are cheap frozen there.

Yes, Cebury! My grow bags arrived, and they do have holes in the sides. YAY! JD and I might just drill a few more... air pruning and all that!

Thanks for the compliments on the children! I love them so!! It appears to be an addictive thing. I have a couple favorite rose bushes (Our Lady of Guadalupe) and Veteran's Honor, and the rose propagation forum sucked me in! I'm trying to root those also! Just for me. Not for sale!! Veteran's Honor is the most beautiful, perfectly formed, best scented red rose on this earth!! Our lady of Guadalupe is a perfect pink floribunda that blooms every day 3 times a day.

Cebury, I respect your opinion, and I don't think you have a vineyard, nor do I. I have a "hope" for a vineyard, and I have vines growing big time!! It takes a few years to get premium grapes.

Challenge, Cebury! Plant some Vitus Vinefera in your containers! Let's see who's grapes make the best wine!!


    Bookmark   June 6, 2010 at 7:33PM
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Umm....I fell into the same trap of "1 is good then 100 must be great" for citrus and now other fruit trees and berries. If I start with grapes (which happen to be my mom's favorite) I'm sure I'll end up spending even more money, time and effort making wine! I best stay away from that for now. But I can't avoid sneaking peaks at them whenever I'm at a nursery.

My wife loves the fragrance of roses, lilacs, etc. I've made some poor rose purchases in the past, believing the tags that said "wonderfully scented" and they were mild at best. The Mr. Lincoln was great, but alas I have it no longer. I didn't over-winter my rose containers very well and it was the only one I lost. You're tempting me to find a Veteran's Honor and Lady of Guadalupe. I still have several spots available in the front yard for roses.


    Bookmark   June 7, 2010 at 7:55PM
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OOOOH, send me your evil bougainvillea, I'll put it to good use!!!

    Bookmark   June 7, 2010 at 9:15PM
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Suzi AKA DesertDance Zone 9b

granburyflowergirl, Be careful, little girl, what you ask for. You just might get it!! :-) I'd be happy to send it to you if it was in a container, but it's not. It is deeply rooted in the ground. My big option here, is to do it in! I have a lot more bougainvilleas though, and I could send you cuttings! Mine are that bright fushia reddish color.

Chris, I hope you find Veteran's Honor, although bare root rose season is over. My roses are in-ground, but I might containerize a few just to get more of that one!

    Bookmark   June 7, 2010 at 10:44PM
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bubblegarden(z9 Bay Area, CA)

It seems I am in a similar area... hot and windy... my citrus trees in gritty mix (1:1:1) needs water everyday for hot days. Since I was not able to water it everyday, they are not very happy and healthy now... As such, I am thinking to try the modified version. The only concern I have for this mix is if vermiculite will break down easily. Gritty Mix (1:1:1) is supposed to last 4-5 years without transplanting. If vermiculite is used, how often do I need transplanting?

Can I skip vermiculite? or can I substitute vermiculite with something else?

Please advice.

    Bookmark   July 27, 2012 at 5:29PM
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Why don't you use extra 'turface', the ingredient that holds the most moisture in the mix?

For instance, give 1 part bark, 2 parts 'turface', and 1 part granite a try.


    Bookmark   July 27, 2012 at 8:47PM
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