I was told that for the clay soil that has very poor drainage I should build up a mound so water doesn't lay because of poor drainage due to clay beneath. What is a good mixture for adding soil. Should I buy bags of humus, bags of top soil mixed with dry peat moss. It gets expensive buying the prepared bagged planting soil. Would like to make my own mixture with purchased product. In adult community - cannot compost.
florida clay soil - topping it with what kind of mixture?
Aloha domenica, and welcome!
No doubt someone more expert that I will be along to answer your question, but what about crushed lava rock? It seems to me that anything like peat will waterlog the soil even more...
We are all in far flung time zones so we always have a time lag with answering questions on this forum, but we have some wonderful growers here - I know Christi has difficult soil to work with in Texas - Yohoo, Christi - where are you?
Jen
Domenica...I would suggest a local solution...your University Extension Service should be able to help you as well as the local Master Gardeners... They would have knowledge to help... I know that in Seattle I rototilled bags and bags of sawdust (from untreated lumber) and sand and peat into my clay soil but it took years before it broke down and I got good soil. Container gardening?
Carol
Gypsum (Calcium Sulphate) helps break up clay and is often used in those type soils.
In a flat yard, the most manageable way to deal with clay soil is to raise the bed well above the clay soil. The main reason is that without a slope, any hole you dig into the clay becomes in effect a pot without a drainage hole. With a slope to work with, you can dig the bed into the soil, as long as you also dig trenches for drainage. And the trenches really have to work --the bottom of a trench must start at the lowest level of the hole, and go downhill from there. Don't just "eye" it, TRY it, or you've only wasted time and effort.
How high to raise the bed is another question --the most basic rule is the more bed surface area, the lower the bed can be. Minimum height would be the height of a pot in which the intended plants would otherwise flourish. The "rule" on more height for a smaller surface area recognizes that a raised bed will lose more water by evaporation and runoff from its sides than a dug bed. Thus, if you are enclosing the raised bed in a frame --particularly if the frame has an impermeable liner, you can go with the minimum height.
In any case, a raised bed approach --which reduces the amount of soil you need to move-- will always benefit from breaking up the clay soil beneath it, to at least some degree. You don't have to move it away, just bust it up and do add the calcium sulphate, even go for some organic material if you have the time and muscle available. At very least, doing this will help reduce runoff. Over the long term, it will allow you to deepen a large bed --but drainage is still always the limiting factor. Where you can create even moderate drainage, from a given level below the existing clay soil, it's smart to do so.
I will try to link you to another thread where tapla has wisely and wonderfully expounded on soil mixes. In the meantime, fine pine mulch should be at least a third, up to half, of your raised bed mix --the pieces break down slowly (years), hold moisture, don't wreck soil chemistry, and provide good aeration. Mix should also include another 1/4 sphagnum peat moss, 1/4 perlite or vermiculite, some lime [although FL soils are already alkaline, as noted below, so check this], some controlled release fertilizer, and some composted manure or "micronutrients".
More (much, much more) from Tapla the Terrific: http://davesgarden.com/community/forums/t/527353/
Hope this helps.
This message was edited Mar 28, 2009 1:41 PM
Great information, JP...thanks
Using mulch always helps soil to improve. A local source which you can get for free (leaves, lawn clippings, bark, etc.) would be best.
As I remember, Florida soils can be very alkaline. As mentioned, things containing sulphur can help. Fertilizers such as Potassium Sulphate and K-Mag can help the roots of plants penetrate the soil. Miracid (Miracle Gro) may help.
Lavarock does work, but best where the planting is permanent. It's a pain if you are going to dig the bed and replant things regularly.
Unfortunately I have lots expierence with heavy clay soils. Yes, you'll need to build it up but if you don't change the structure of the soil you will still be planting into a clay bowl. Gypsum, gypsum and more gypsum along with heaps!!! of organic matter mixed in with the beds as well as used as mulch. You may think that worms will eventually turn the bed over for you, I did lol. But the truth is it's easier,faster and you'll lose less organic matter to run off if you turn heaps of it into the soil as well. We leave truckloads of mulch laying around for a year and then add it to new beds as well as into planting holes. The results are amazing.
The other alternative is a no dig garden. http://www.abc.net.au/gardening/stories/s867068.htm
Good Luck!! Sand is a heart breaker but clay is a back breaker :) Ann
HI domenica, I have tons of marl here at our place. It IS a challenge, and you have already been given some great information. What are you trying to plant? Shrubs, trees, perennials, vegetables? Often, at least in my area, there is a point that the clay ends and sugar sand begins underneath. For most small trees, shrubs and palms I just dig down until I hit sugarsand and creat a hole larger than the rootball for backfill. The depth of the marl varies widely throughout our yard and I've also encountered that soup-bowl effect that pogonantha referred to. I keep lots of sulfur around as metro suggested. I think JPlunket's suggestion is also very good, and it is my plan to "someday" build a huge raised garden if and when I ever get around to it for vegetable gardening.
I would also suggest that you try to work with the marl in areas where it is too deep or too unreasonable to try to lower the pH. Shrubs such as the native marlberry thrive in it. Some palms such as Pseudosargentii have evolved in those kinds of soils and some trees don't mind wetter/poorly drained soils.
As far as making your own soil mix, I can totally relate to that! I make my own potting mix as do many other DG'ers here, but for backfill in the yard try to see if you can find a local soil/compost/mulch company and a friend with a pickup so you can buy it in bulk. Some communities have free compost available as well, and I would mix that with some peat and lots of coarse sand- only reason for the peat is that composts generally can be alkaline as well like the clay soils around here. The mulch is a good idea, but don't allow for large pockets of it as it will eventually disintegrate and shrink.
Good luck!
Buying a truckload of soil is VERY risky --I can speak first hand. It's very difficult in particular to determine the clay content. Especially in areas where clay soil is prevalent, the risk is very high that you'll get "rich topsoil" that's really just clay, disguised with some cosmetics. THe "dirt guys" are very clever. They will take clay soil someone has paid them to take OUT, they allow it to dry, bust it up into small pieces, then re-wet and mix it with fine peat moss --all the chunks get coated and give the appearance of nice rich composted soil. Then they mix in a small proportion of various-sized organic material, sometimes a little sand, load it in a truck --AND put a layer of nicer mix on top. Even if you inspect it, unless you dig well into the truckload, take a truly representative sample and wash a good shovel full in a large bucket of water, it's very tough to know what you're getting.
I have learned not to buy any bulk topsoil that I have not SEEN MIXED MYSELF, or from someone I REALLY trust. I learned the hard way --don't do that to yourself.
I couldn't figure way to send link. This from a free web site. I've used it but just for trace elements, not for breaking up clay. I would use compost for that. But, as several have already mentioned, I would use above ground beds or mounds. This is a recent article he wrote.
Improving Soil with Greensand
Today I'm going to tell you about a wonderful organic product
that will improve your garden and potting soil.
Greensand is a naturally occurring mineral that is mined from
ancient sea floor deposits that has been used as a fertilizer
since the 1700s. In the U.S. greensand is found mainly in
Texas, New Jersey and Arkansas. It is completely organic and
safe to handle. It will not harm insects, pets or people and
is so safe it can be scooped up in your hands. Greensand can
be applied to the garden any time, and unlike chemical fertilizers,
it will not burn your plants if applied too heavily.
Now here's the best part: Greensand will help loosen up clay
soils and help bind sandy soils. It also retains water and will
increase the soil's ability to hold moisture. When greensand is
mixed into potting soil, less watering will be required for your
potted plants. Greensand looks much like fine beach sand that
has been tinted green, but it is able to absorb ten times more
moisture than beach sand. The dark green color of greensand is
natural, and the when greensand is applied to the soil surface,
its dark color will help absorb sunlight and help warm the soil
in early spring.
At first glance, greensand may not look like much of a fertilizer.
It has an N-P-K rating of only 0-0-0.1 to 0-0-3 which means it
contains no nitrogen or phosphorus and only a slight amount of
potash. But it is the trace minerals present in greensand that
prove its worth. While plants need only tiny amounts of these
trace elements, they are essential to a plant's growth. Greensand
will provide calcium, manganese, and over thirty more trace
elements for your plants.
An application of greensand will improve the soil and thereby
improve the health of your plants. Greensand will make roses
bloom longer and it will make tomato plants produce tastier fruit.
If your garden soil is heavy with clay or sandy and weak, a dose
of greensand will make it more suitable for your plants.
Whether you buy Jersey greensand, Texas glittergreen greensand
or Arkansas greensand, always check the label for instructions
before applying this amendment to your garden. Application
rates can vary from 5 to 80 pounds per 100 square feet, depending
on the specific needs of the soil.
Greensand can be found at garden centers and in some gardening
catalogs. If your local garden center doesn't offer greensand,
ask them if they can order it in for you. Your garden will
appreciate it.
Have a great week!
-Mike McGroarty
Larry
I live on the Texas Gulf coast and the soil here is a "gumbo" clay soil also. Raised beds are the answer. 6" to 8" raised, using a heavy garden mix containing some masonary sand. A landscape supply company that sells mulch, sand, etc. should have a Garden mix sold by the yard for making new beds.
i finally got back on to daves garden - its been quite a while since I was able to get back online to find out if I had any responses. my computer hasn't been available to me. I want to thank all of you for your time and wonderful information. I have printed out all replies and will read them thoroughly and follow the instructions you have sent. its so nice to hear from people nearby and also so very far away as Australia, PR and Hawaii. Thanks again.
Don't be scarce!
Aloha, Dave