What you have is almost all organic matter, not "dirt". Too much organic matter can create conditions that cause the growing medium to repel water. A good growing medium for raised beds, not small containers, is a soil composed of between 92 and 95 percent of the mineral component of soil (sand, silt, clay) and 5 to 8 percent organic matter.

Does everyone mulch? Or at least loosen soil with a cultivator? It seems to me that lately I have seen pictures of unhappy plants in dry flat surface soil, or happy plants, mulched.

Two words:

Peat

Moss

Once it dries out, it is the devil to rewet. In a container, by far the easiest way is to dunk the pot in a larger container filled with water. Otherwise, it takes multiple, small waterings.

If the conditions are such that keeping the peat moist isn't possible, then replacing it with a non-peat based potting soil would help.

I have sometimes thought that peat moss would suck the water away from the top. Meaning that the moss at the bottom may be drier than the moss on the top (which you water frequently). As a result, the dry moss wicks away the moisture from the top moss. Normally, wicking may go from bottom to top, but that is when you are having the source of water from the bottom.

I have also heard that if you mix in peat moss but that moss is not wet or moist to begin with before getting mixed, then when you use it in your pot or bed, the mixture looks dry, even caked.

So I don't know if there is any useful information in what I posted, but those are my thoughts on my a peat mixture might still look dry and even worse, the plants look like they are wilting.

However, at the same time, many plants do wilt in the afternoon sun. They usually should recover overnight or in the morning. So don't overwater in this case, though your comment about how you checked the soil moisture level seems like it would cover that point.

By watering too frequently, even several inches in a week, then the plant doesn't make deep roots in search of water, so as the weather heats up and sun gets more intense, that may have detrimental effects.

mad__ gallica has nailed it - your problem is the peat moss. Once it dries out on the surface it becomes hydrophobic and will repel water. Unless one is needing to alter soil pH for acid loving plants, peat moss is not a great choice for a soil amendment or ingredient for raised beds. Neither is the vermiculite, for that matter. Both are expensive and serve little purpose.

All you need in raised beds is a prepared (bagged) planting mix or similar product from a bulk supplier or a mix of topsoil/loam and compost at about a 70--30 ratio.

Im having the same problem. I wonder if i just add some bags of putting soil in my raised bed and mix it in would that help the water to absorb and not just stay on top of soil? Also some of the soil is clay and rocky. I took out alot of the rocks sifting it but that didnt help.

>> your problem is the peat moss. Once it dries out on the surface it ... will repel water

So many hearsay causes and if only half of us are right, you're doomed! Peat isn't a problem. Repelling water is silly. Tossing good dirt because it has peat is silly. I grow plants in nearly 100% composted manure/bedding, and ratios are silly.

Only you can fix this because only you can check things out. The problem is that more moisture is going into the air than the roots can supply. My wild guess is there's not enough moisture, not enough root, or diseases/poisons. "the dirt was dry and almost sandy feeling just beneath the surface". Wilting is not really tied to surface moisture unless the plant has terrible roots. How deep did you probe before you found dryness? These "soils" can suck up a surprising amount of water, and rain can be surprisingly shallow. "I'm not sure why the water isn't soaking into the dirt like it should." That sentence is scary. Is it running off? It's a drip, right? Please tell us HOW you water, how fast, how long, and so on.

If I had hot wilting and there was good watering going on, I might try some shade on the leaves and maybe also on the roots/containers. Nothing fancy, just a sheet, tarp or cardboard, to maybe help the plant skip the harshest stress. Don't cut back on the thick layer of mulch you've already put on the dirt.

This post was edited by cold_weather_is_evil on Fri, May 9, 14 at 21:20

Peat moss should always be made wet before using. I make a small hole in the bale and add as much water as it will take. Let it absorb and add more. Once the bag is open I add more water every time I use it. When it's already in the garden it may be more difficult to wet but you might be able to use a surfactant (wetting agent). I don't think I'd want to use detergent near plants but perhaps Safer's Soap would work. Maybe about 1/2 - 1 tsp. per gallon would help.

Turaloora, bagged potting soil is mainly peat. It's a lot cheaper to just buy peat.

I don't know why so many people are knocking peat. It's a great amendment for sandy soils. Being afraid of hydrophobia is silly. Clay can get hydrophobic and so can sugar sand. You just have to figure out a technique for wetting it. Flooding works great. Another option is low precipitation rate rotors. Then irrigate enough to wet it and keep up with evaporotranspiration.

I have a great solution to the never-ending peat moss debate/debacle-- university studies.

Bring it on!.

We have fifty different university systems, so there should be a plethora of studies somewhere out there, just have to find them.

All conclusions presented to the forum shall be based upon published, peer-reviewed, repeatable, verifiable results from "experts" in their respective fields (horticulture, botany, soil science, biology, chemistry, and any other useful disciplines that come in handy (scientific method)..

Let's try and put an end to all the anecdotal advice out there on the subject...

No more anecdotal advice, or M busts out his secret weapon, Kim Fung Suey!

Yours truly,
Mackel

(Hickenese for Michael)

Here's my proposal-

What is superior ?

Compost in a raised bed, or peat moss in a raised bed

M

>> Compost in a raised bed, or peat moss in a raised bed

That's a trick question; too simple. Growing or sprouting? Two square feet two feet high or forty eight square feet three and a half inches deep? Organic or Monsanto? Cutting flowers or smoking flowers? Double-dug or concrete driveway?

There are two problems we come up with every single time. One, everybody (especially me) thinks their way is the best way. A few think their way is the only way, but most of them guys have been shot by now.

Two, everyone has a different climate and micro-climate, so everyone does things differently. "Different-like" if you're from Winchester Virginia, a town so into apples that they have an apple blossom parade every Spring and an apple harvest parade every Fall. I digress.

Three, some people take this scary serious. Protecting-MotherâÂÂs-honor serious. Blood-on-the-flag serious.

Three and a quarter, it's reaaaaaaalllly hard to not give bad advice. I swear on my motherâÂÂs honor! It's harder than counting.

All we can do is try.

After just a cursory search, I couldn't find any experiment on the web that compared the two. I only spent a minute or two looking, though.

This is what I strongly believe, however. A raised bed should contain native soil The purpose of a raised bed is easy access, superior drainage, and better weed control.

Native soil in a bed means there is less of an inhibiting interface created by two unalike soils that butt up against each other at the bottom of the bed. With proper irrigation, roots can go deeper, and have greater access to moisture and nutrients.

So, onto amendments...

With compost amended native soil, the soil is more alive than with peat moss amended soil. Peat moss is basically sterile, so why would someone think that living roots (life) would prefer peat moss amended beds over compost amended beds?

Someone answer this. Step up to the plate.

In addition, when peat moss or peat amended soil becomes hydrophobic when dry, it becomes extremely hydrophobic, much more so than dry clay, or dry compost, or dry anything.

This means that you have to water it more to keep it moist, as water will not penetrate to the lower roots of the plant as well as compost amended soil. So there is greater drought tolerance for a plant growing in compost amended soil than peat amended soil.

This is becuase gravity must overcome hydrophobicity to a much greater degree with peat moss when it dries out than with compost. So, you wind up with shallower roots given the same volume of water.

This is not good in the heat of summer. It's a waste of money, as you wind up with shallow roots unless you water it much more than would be otherwise necessary.

There are other reasons why I strongly believe peat moss is inferior as a bed amendment to compost. But these are just a few. I'm hittin' the hay, gnight.

M

This post was edited by Mackel-in-DFW on Sat, May 10, 14 at 1:18

I think gardengal (and kimmsr) has it right, you need more mineral soil. I am a big fan of clay soil and I've learned how to work with clay. Clay holds water well.

When I've loaded too much compost and peat moss onto the soil, I also get hydrophobic conditions.

When I've mixed various sources of organic material with the clay soil at my Idaho home, I find that the OM will soon break down and be absorbed in the clay. The clay is altered by the OM; it becomes much looser and friable, and changes color. Water easily percolates into that soil.

Lordy murphy, folks - look it up!!! Peat DOES become hydrophobic once dry. If the moisture content declines to about 10% - very easy to arrive at if the peat is exposed to air - the chemical properties change and it WILL repel water. It is also very difficult to rewet at this stage: "Peat is characterized by colloidal behavior and irreversible loss of wettability produced by drying" (see attached link). Irreversible loss of wettability!!

As far as the discussion between peat and compost in raised beds is concerned - and I realize this is hypothetical - there is no comparison. Peat has a pH of around 4.0 - far too acidic to be appealing to virtually any plants without buffering. It also has virtually no nutrient content, so not able to support much biological activity in the soil nor provide nutrients to plants. It is also too small a texture to achieve proper aeration and drainage.

So before we start throwing around words like "silly", lets do a little research, huh?? For any number of reasons, peat is not a great soil amendment unless you are actively attempting to acidify your soil. And for heaven's sake, DO NOT allow it to dry out if you do use it.

Here is a link that might be useful: scientific paper on the hydrophobicity of peat soils

I used to use copious amounts of peat moss in beds, and it certainly is hydrophobic when it first comes dry and compressed in a bale. Putting it on as a top mulch, it can stay dry for weeks if not months. If it hasn't blown away.

I also agree that mixing in a bit more regular soil might be the easiest way to over-come the problem. I can't explain why, but it works.

Related: "University of Florida study: Mulch reduces soil water loss to evaporation by 33%"

" In this case lysimeters were used to measure water lost from containers filled with soil or container media (60% pine bark : 30 % peat: 10% sand) and then covered with pine bark mulch or left uncovered. "

Here is a link that might be useful: garden professors

Thank you everyone for your input!

When I mixed the soil, I followed the "Square Foot Garden" method. The theory was that the peat would keep the soil loose and friable, the compost would keep it fed, the vermiculite would hold in water. And until recently, I've never had a problem with the mix. The plants have always grown fast and healthy.

I'm not sure what would have changed to cause the drying out, but perhaps as many mentioned, the peat closest to the top of the soil became dried out in the heat which is now hitting the 90's during the day and began repelling the water.

Hand tilling around the plants had an immediate effect and the water began draining into the soil instead of running off. I think my compost may also need a booster since I didn't add much new compost in this season.

I also like the idea of mulch.
What kind of mulch would you recommend--dried grass clippings, pine bark, pine straw, cypress?

The reason for using raised bed with non native dirt aside from weed control was because my native dirt is complete crap and only native plants grow in it. I failed for two years to grow any veggies in it because it's so terrible: sandy, nutrient-less, and will not absorb water.

Here is a link that might be useful: My blog showing pictures of all my containers/beds

I would have said "whatever mulch is cheap and available in your area," but I guess we have to be a bit more careful than that now (link). But certainly there are many good choices.

Good luck, the garden is looking good

Here is a link that might be useful: Killer Compost

"So many hearsay causes and if only half of us are right, you're doomed! Peat isn't a problem. Repelling water is silly. Tossing good dirt because it has peat is silly. I grow plants in nearly 100% composted manure/bedding, and ratios are silly."

So, you say that peat isn't the problem, and then immediately say you don't use peat.

Peat goes hydrophobic if it dries out completely. This is known. It's not a great soil amendment unless you really need to acidify soil.

You have to soak the crap out of it, and use a wetting agent (I think some people use a really diluted dishsoap). There's a reason that pretty much every potting mix that uses peat contains some sort of wetting agent.

Gardengal that link is broken

:edit: i think i found it throuh google.

This post was edited by nil13 on Mon, May 12, 14 at 11:28

So peat can irreversably lose moisture holding ability if allowed to air dry down to 7% moisture. Who lets their soil get that dry? Most places in the US you wouldn't even be able to get it that dry because the air humidity is much much higher than that used in laboratory protocols. What is important is the Plant Available Water in the soil. If the peat is not allowed to completely air dry, the PAW is drastically increased by the addition of peat. If the peat does air dry, depending on how dry it becomes, the PAW is still increased. It just isn't increased as much as it could have been had it not been allowed to air dry. Peat has been successfully used as anadmentment in scores of golf courses for an exceedingly long time.

We should also be careful of extrapolating the results of studies that look atpeat soils with 40% peat and om levels of 70% as that isno where near the levels anyone would be achieving with simple amending.

Here is a link that might be useful: Peat in turf soils (pdf)

The "or" above is significant, between "soil" and "container media"
Now hereâÂÂs the important part. If you look at evaporation for the soil-filled containers" which are the ones we really care about from a landscape perspective" total evaporation was 3L for non-mulched containers versus 2L for mulched. In other words, there was much greater water loss from soil when the pots where not mulched. A much better title for the article would have been, âÂÂMulch reduces evaporation from soil by 33%âÂÂ!

BTW, specific to vegetable gardens, I think the primary strength of mulch is that it protects the root zone of young plants. Without it, the root zone of your lettuce may become the mulch zone, forcing the plant to believe it is in drought conditions.

It is the peat moss, you should try adding real compost, home made compost, is the best thing at keeping the soil moist. You can recompost the peat moss by adding to the compost bin.

Nilly-

My roommate in college was an architect.

I've known architects all of my life.

And you sir,

Must've got stone-walled

by a hot science teacher

back in the day (!).

Nyuk, nyuk, nyuk,

Mackel

I have no idea what you are talking about. I was an engineering major with years of advanded math, science, and statistics under my belt before it became too boring and I went to do something more challenging and entertaining.

This post was edited by nil13 on Mon, May 12, 14 at 15:43

My dad was an engineer.

My brother was an engineer.

My grandfather, both uncles, and some close friends....

And you sound, just like an engineer (!). Lol.

(Throw in some technical terms, provide vague notions of a conspiracy (the anti-peat moss thingy), lament how the world ignores your good intentions/wisdom, pontificate some more on an anecdotal "discovery", dust off the palms of your hands, go out to the garage and grab yourself a beer. Yuppers!)

I've seen it all my life -> from people I dearly love. I have enjoyed many engaging, stimulating arguments with each and every one of 'em.

But in this case, I don't want to do all the work, and disprove your hypothesis. In my mind, I've already seen a glaring error in your above post. Work a little harder to disprove mine.

"Stone-walled". Awesome term. Don't be stone-wallin' me, Nilly.

M

The engineer guy>> provide vague notions of a conspiracy (the anti-peat moss thingy)

You, sir, have awesome terms yourself. I love it!

The other guy>> So, you say that peat isn't the problem, and then immediately say you don't use peat.

Why do people love to argue so much and then get huffy about it? An argument that is imperfectly phrased is not proof of duplicity. You, sir, could read a little better. I use peat to sprout. I use old manure to grow. It's all good!

to everyone else who took this thread sideways:

There's nothing wrong with peat, or manure, or Mel$ Mix, or ground up bark in sand and coffee grounds. Whatever works, for wherever you are doing whatever you do, that fits the way you work.

The stupid (that's "silly" for dense people) thing is to say is 1) another person is wrong because that person does not agree with you, and 2) peat's no good because you don't use it and that makes you an expert on it. Stuff like that is often a reaction to screwing up royally one year and looking for something to blame other than one's self.

End of tirade. Tirades are silly anyways. No more replies from me. Well, maybe to the engineer guy...

When Mackel starts cracking jokes, it's like spotting a turd in the pool. Everybody out.

Good one, Nilly.

M

What I've noticed over the years, Nilly, is that when you present a bullet-proof hypothesis, for the benefit of newcomers,

and resident posters repeatedly want to argue with a specious counter-point,

you're either left with playing into that game, or laughing it off.

Now what do you think is a healthier way of living one's life? Get shouted down, and walk away ? Why hell no.

The best thing I ever learned is that I don't take you (or anyone else) so seriously, because I don't take myself too seriously.

Here is a website dedicated to the "intellectual appreciation of poop humor".

M

Here is a link that might be useful: Hope you enjoy...

I think someone is off their meds this week.

Back to the subject, it always amazes me that people fill their raised beds with potting soil! Or some other form of nearly 100% organic matter, and then they wonder why it doesn't act like soil. :-]

Neener neener neener, you're swimming in POOP WATER, LOL !!!

Have a nice day, Sir Toxalot,
(I mean it).

Mack the Lifeguard

Kimmsr and Gardengal have it right, what else can be said? I have one 6x4 bed out of many others that is set up exactly like the OP's.

Growing in it is a prized bamboo, that has been upsizing now for 3 or 4 years. I don't get rid of it, it indeed works, but is more work and water. .I don't want to disturb the plant..

It shouldn't really surprise anybody, T, that people do what they think works, and once it appears to work, never look beyond to what may work better, and cheaper, and easier.(They also like to argue out of a foolish sense of pride.)

M

I rarely say anything good or bad unless I've tried it. As a highly motivated biologist, tinkerer, and experimenter, nothing is a failure. Just an opportunity to see something for one's self. It's the Missouri way.

M

I absolutely have to go to work, Sir Toxalot. Any of you resident Stooges who would like to give me a hard time, I have a very thick skin. Bring it on! I simply try to minimize time spent on round and round, circular logic and debate. You should, too. For your own serenity.

Clean, Sober, Unmedicated Mack

Here is more logic for engineer-types--

With alkaline soil areas, peat appears to have postive effects because the salts (excess minerals) present in irrigation water (Los Angeles?) easily move through the peat-amended soil profile, as the acidity frees up these minerals that would otherwise tightly bond to the non-peat amended, alkaline soil.

(The salts, if allowed to accumulate in alkaline soil, will eventually impede root growth to a very large degree. This occurs often, with improper, shallow watering techniques.)

However, where amended soil (peat or compost) in a bed butts up against non-amended soil beneath, a barrier is created that produces a perched water table, which holds up the salts from being further flushed to safely below.

Ordinarily, to get around the accumulation of salts that inhibit deep root growth in alkaline soil, deeper watering is called for, and less frequently, which will push the salts lower simply due to the large mass of water combined with gravity.

This is not easily accomplished with peat amended soil. Peat holds water so well, compared to compost, (if it remains hydrated), that it is eventually evaporated off or used up by the shallower roots before it is allowed to travel further in depth. Simply watering more can drown the plant or it will find a place to run off.

So, the gardener loses one of his/her best tools in keeping the root zone free from accumulating salts by using peat. Therefore, lower drought tolerance, with shallow roots is the result, and weaker plants.

I'm not certain how an an engineer wouldn't agree, with a little bit of patience of the technical talk. The ones I know are all on board, once they thought it through.

M

I hope that's enough fer ya, Nilly, before I have to bust out my secret weapon, Kim Fung Suey. I have a brown belt in nonsense humor, just sayin'. Sir Toxalot is pretty good at it too, as we both learned from our resident Master.

Glad you're reading this and you've made the commitment not to wade in, since you sensed a turd somewhere. Me, I prefer to only swim in natural water, like the spring fed watering holes that dot the South and Midwest. Chlorine schmorleen.

Schmakel Mackel