Though I cannot give a definite answer as I too have only been going at it for about two years, I can recommend solarization of the soil. If your main concern is deceases/pests in last years soil, rather than loss of nutrients, then solarizing might be what your after. The basic premise is to cover the bed with a thick clear plastic, and allowing it to bake like this for a few weeks. The temperature of the soil will raise dramatically killing off most everything living beneath it. I hope this helps some.

Thanks for the reply. I have tried soil solarization, when I was raised bed gardening, and for me it did not work at all. I did it according to McCubbin's/Stephen's/EDIS-IFAS instructions--clear plastic, weights along the edges, ten weeks or so in the middle of summer--and nothing. It didn't even kill the weed seeds. But again the soil in those beds was VERY infested with every disease/blight/wilt known to man, so maybe I just waited too long to solarize. Or maybe solarization would be a better technique for less intensive veggie gardening (?)

Hi Bill
Jonny made a good point. Solarization works, it did for me in Arizona. I garden there for 10 years with small space. They also claimed they had nematodes (I have been hearing this word for quite a while):o) As for me, I never had this problem.

I also did other things:
- Never dig
- Put a lot of organic material, newspaper, hay with no weed seeds(I always asked for this at the feed store), good soil (store bought), peat moss, etc.
- Mulch heavily (again with hay)
- Slow release fertilizer. anything with no smell
(important) this way is not attractive to pests or worse
my dogs.
- After harvesting, replace it with new soil.
- When the bed was new, I let it sit for a week or two.
- Use cover crops, I use a lot of low growing clover,this
way I could plant in between big plants like tomatoes.

As for tomatoes, anywhere I garden, I either rotate or use containers, they are just prone to diseases no matter where you live or what you spray.

I have been gardening since I was a little child. Me and my father had a garden that I could never replicate it anywhere. We had so many medicinal herbs, fruits, vegetables. It is only a memory now, we didn't have digital cameras then.-)

Silvia

After harvesting, replace it with new soil.

That's the part I'm trying to avoid :-)

As for tomatoes, anywhere I garden, I either rotate or use containers, they are just prone to diseases no matter where you live or what you spray.

I agree, lots of bad stuff seems to be airborne not just in the dirt.

Denise

Hi Denise
If it wasn't for your picture in another post of the root damage from nematodes, I would not know it.

I used to buy seeds in Arizona in a place in Tucson that sells Native American crops. One time I bought a tomato that I think it was native to Chiapas. I planted on the soil, next to my cactus garden and forgot about it. It was so hardy, you could kick it and still live. Plant was stocky, short and gave small red tomatoes.

So many tomatoes, so little time.lol

Silvia,

Could you tell me more about replacing the soil?

For example are you replacing the soil in your raised beds once a season, or once a year?

Do you reuse this old soil? How? (Do you plant, say, lettuce in soil you used the previous season to grow beans, and, if so what do you plant after the lettuce? Or do you just use the soil once for veggies and then use it under fruit trees or ornamentals?

In other words, what's your rotation scheme?

Do you reuse the container soil too?

Thank you!

Bill

bill knows my thoughts on this matter, but i'll chime in that it's not all or nothing--i use all three methods depending on the plant and the age of the bed. tomatoes and peppers--i use the 'posthole' method--dig out 4 gallons of dirt and replace it with 4 gallons of compost. (actually this year i replaced it with 4 gallons of mary's cow poo... and it's working better than anyting! the plants are so dark green and vigorous... plus, it was free and i got to hang out with mary picking up cow patties.) lettuces i grow either in window boxes that are half-buried, or i spread a 2-3 inche layer of mushroom compost directly on the soil. (lettuces have very shallow roots.) beans and peas--i plant directly in the sand, and then mound up compost on top of each seed, then cover very heavily with any sort of trash mulch (leaves, hay, grass clippings, wood chips.) i also grow a lot of things in pots, buried pots, pots-in-pots. the pot-in-pot method is working incredibly well with my cukes this year. i have several 2 and 3 year old peppers in pots. bananas i grow in sorta raised beds--i put the plants on the ground and then bury them in 8 inches of mulch and compost. (i just started that method this year after seeing how christine grows hers.) collards and broccoli--straight in the sand, and then heavily mulched.

I've moved a few veggie beds around this season, and let one ground level growing patch that had okra, tomatoes and peppers for a season go back to grass. I had one raised bed out by the road in front of my house that I had built up to almost three feet high, because I thought it would be so cool to be able to sit on the sides while I weeded (and it was), but after I used it for about a year and a half, I realized I was gonna have a really big stockpile of used soil to get rid of and no place to put it. (It had been been filled from the ground up with layers of mushroom compost, leaves, pine bark fines and clean playground sand when it was first made)
So I decided to break it down in stages. What I did this year was make new beds and use the top half (the bulk of the depleted portion) of that 2.5 foot soil layer as the bottom layer of the new beds. I mixed in new lime granules and fertilizer and leaves, and then used newly bought mushroom compost and clean builders sand to make the top half of the new beds. I'm hoping that the juicy goodness from the compost will leach down into the bottom layer over time and make it richer before the roots of the new plants get down that far. About the mold spores and weed seeds and bug larvae, and various bacteria - the heck with them. I know a losing battle when I see it, and I'm just gonna cross my fingers and hope for the best on that one. I fluffed the bottom half (now the surface) of the old bed and just added about an inch or two of the mushroom compost I bought for the new beds, and went to town with the seed sowing. So far all the plants seem healthy and happy, even though I flat forgot to ever put any new fertilizer granules in that bed. I really do think that the top foot of the beds is all that needs replacing usually. Anyway, it's working so far!

Bill
I always have a bag of soil available, sometimes I use Black Cow manure too. It meets the requirements (no smell).
Everything I reuse. For example, I harvest a cabbage, there is a big hole after taking the roots out. I put in the space fresh soil, only in that part of the bed. Sometimes it is just like a handful, sometimes is more depending on what I take out.
The soil in the containers that I use for tomatoes, after the season is over, gets put around the bananas, other fruit trees, herbs, ornamental. I always use fresh soil for containers. Usually a mix of soil and pine bark fines (is cheaper and it drains faster)

The rotation goes something like this (Of course this is flexible)
Root crops
Beans
Squash
Greens

Let's take bed N1
I planted lettuce, spinach and other greens.
Then carrots and beets
Now it has beans
Later it will be something else.
And I always plant flowers that I grow from seed. It helps with pollinators and visual effects.

If I am not too clear in my explanation,please feel free to ask me any other question you have.

Silvia

Thanks to you all for the info.

Silvia, one more question: so you never Completely replace the soil in your raised beds? (that is, you only replace the soil that comes up with the roots of a harvested plant, and never clear all the soil out and start over?)

Ill, are you rotating the in-ground (or in compost)crops? Do you ever till or work the compost into the sand before adding a new layer of compost/mulch on top?? Have you had any problems with soil born diseases, or does the new layer of mulch/compost protect the veggies?

Karen, I'm very attracted to the "the heck with them" approach too (it's pretty much what I'm doing now with everything except tomatoes and peppers). I'm hoping I can stick with it!

Bill

Have you had areas of the bedding soil tested recently ?

Sometimes mushroom compost can become quite alkaline over time . If the soil is not in the proper pH range , nutrients cannot be taken up by the plant . A weaker plant then becomes a disease and pest magnet . Sounds like the debate with Tillandsia and Oak trees , doesn't it ?

Bill - your garden always looks gorgeous- just like a seed catalog ad - so I would never have guessed you have been having problems ! With today's rains you can bet we might see some fungus pop-up soon . So many fungus spores are air born or wind born so it is difficult to pin it all on just the soil .

This veggie gardening stuff sure is complicated !

Yes Bill, I never completely replace the soil in the bed. I only add.
I think like if it was money in the bank. If I only take out and don't replaced it. Eventually gets depleted.
I also add small amounts of fertilizer.
Remember how the soil is replenished in the wild, leaves, organic matter, everything decomposes over time...

I forgot to tell you that the reason me and my father had a "dream garden" was because of the soil. We were living under a rich, black volcanic soil. I never in my life saw such soil again.
Everything grew with no effort, I can tell you there was no bags of soil or even nurseries that I can remember. :o)
In the back of our house there was a forest with the most delicious wild berries, small black coconuts like the taste of a black walnut and so many other things.

After that, I have to deal with clay soil (Arizona), sandy soil (Florida), and other things. That is the reason the soil has to be enriched and add as much as organic material we can add.

There is many roads to achieve a fine soil. You just have to find out what works for your particular situation. Good luck with your quest. I am sure you will come up with the best solutions.
Silvia

Last month Mother Earth News had an article on a very ancient way to amend soil. When you think about it Mother Nature does some of this with wildfires. Maybe I can burn out the nematodes?

I'm trying to figure out how to do it in my garden without the Fire Dept. arriving :-)

Denise

Here is a link that might be useful: biochar article

Mary, I haven't had any serious trouble yet this year. I'm just anticipating because past experience tells me I will have problems in the future unless I'm prepared. You should stop by and pick some lettuce before the heat makes it all bolt.

You're lucky, Silvia. I've never lived in a place with good soil in my life! Thanks again for the information. It's encouraging to hear that one can keep beds going without having to completely replace the soil.

Denise, that's a fascinating story. Old-time agriculture in the Southeastern U.S. used a lot of burning too. I bet it would really work, but I live within the city limits and I'm afraid some major burning would get me in trouble.

Bill

Bio-char is quite the controversial issue over on the Soils forum .

With a burn ban in most counties of Florida - burning is just not feasible for most of us .

bill, i NEVER EVER EVER till in fla. it makes no sense with our soils to do so--all you do is to rush the inevitable wash of our organic material into the watershed and invite the fungi to play havoc with your plants. in fact, i NEVER use any garden implements in my garden--it's fingers and only fingers. (ok, when i plant trees and dig out those 4 gallons of soil i use a shovel.) i have so much organic stuff in my garden that to plant even large plants i just push it aside, plot the plant down, and then shove it back over the root ball.

over time, the organic material gets washed down/out or absorbed into plants. that's when i replenish. but i hardly ever just spread the dirt--just like silvia, i tend to pack the compost around the new seedling.

the rule of thumb that i learned about roots: the circumference of the root ball is equal to the height of the plant (a foot tall pepper plant has roots that extend a foot in all directions), and the mass of the roots is roughly equal to the mass of the above-ground plant matter. if you think about that, it gives you an idea of how shallow root systems are and how complex they must be. the vast majority of a plants roots are made up of incredibly fine hairlike structures... anyway, that means to me that you should concentrate your organic material at the surface.

Well said Ill - man .
I must agree with you .
Just as with trees -
most people think Florida trees have deep tap roots
when in fact they spread their roots out more like an umbrella .
It's all in the surface structure .

I can't say much about the long term since I've only been living in this house for a couple years but I'm strongly with the "the heck with em" camp about pests and diseases. I do try to rotate my gardens around (not planting the same thing in the same spot all the time with annuals.)

I am very firmly against buying bagged dirt, Just costs way too much. I do get mushroom compost when I can and I have used the free compost from the county too (ya just gotta watch out for glass in it.) We collect most of the neighborhood bagged leaves and grass clippings for the gardens and compost. We ask tree services working in the area if they need a place to dump the chips they can do it at our house. We compost and have a worm farm. I figure the more biologically active I can make the soil, the less likely the negative stuff can out compete and proliferate. About the only things I've sprayed as pesticides or whatnot, were thruicide, organocide, and neem.

My biggest problem seems to be potassium deficiency. I spray with maxicrop but that gets costly when I have most of my yard growing squash, pumpkins, zucchini and cucumbers that are all asking for more potassium (powdery mildew tends to attack those plants when they are weak on potassium.)

Anyway, most of my gardens started as "lasagna gardens" with cardboard and mulch and mushroom compost. We don't till though occasionally we will for or spade through a bed after harvest to try to get rid of most of the annoying grasses.

I can't really see replacing soil though if a particular bed or area seemed to get "toxic" I would probably knock it down and leave it fallow if I couldn't find something that wanted to grow there as a cover crop. I only add organic matter. I don't buy "top soil" or even "sand". I don't even buy bagged potting mix anymore. I just make a mix of old garden or potting soil mixed with new mushroom compost, other compost, some home mixed organic fertilizer and worm castings and call it new potting mix.

I figure the more composted stuff around, the better everything will be inoculated to the possible diseases. I can't say for certain the long term effects of my methods as they have only been going on a couple years but I seem to be doing well so far.

Here is a link that might be useful: TCLynx

Bill---There is so much that I would like to say to you, that the most practical thing to do is to invite you over to see my garden. Maybe Michael and/or Mary would like to come with you. I can promise you some grapefruits and leafy greens (collards, chards, and kales) for you to take home if you are interested. (I know that Michael likes the grapefruits.)

You seem to be very worried about diseases. Sometimes its not the soil but the variety of plant being grown. I find that tomatoes get very few diseases this time of year and I grow mine in the ground. We are still in our best time of year to grow veggies. My garden has grown so much since I posted pictures at the beginning of the month.

Christine

Bill- need a ride ?

tclynx -- ever just consider wood ash? it has to be used cautiously, but it provides a lot of k very quickly...

Great posts/thread- lots of awesome info. Do any of of you do lasagne gardening and if so, what do you do year after year in terms of amendment/digging out old soil? I did one bed using that method this year but I am a little nervous about fungus/pests harboring in the composting materials........(ie squash bugs LOVE my garden and from what I understand they love to hang out in brush, mulch, etc.)

Thanks again to you all.

Christine, I would LOVE to see your gardens and hear your advice. I've been hearing great things about your gardens.
Mary, if you don't mind I would appreciate a ride. Thank you! Michael, will you come too? When should we go?

Ill, it's the inviting fungi--and pathogens in general--to play havoc with my plants that I'm worried about, and I believe you may be right about tilling/spading doing just that (which is why I'm questioning my present technique, and pondering growing in a surface layer of mulch/compost, or even replacing the soil in some kind of container system, instead). I disagree with you somewhat about roots (I go by Weaver's classic study "Root Development of Vegetable Crops") which is one--just one--of the reasons I hesitate to abandon tilling/spading.

TCLynx, thanks for the information and the link. Again I'm tempted to just stay in the "the heck with them camp" and hope for the best. Look forward to explore your website.

Bill

I'm sorry to say that I have not updated my web site much in the past year. I've been spending most of my internet effort over on the Backyard Aquaponics forum in the past year but there is still some info on my website.

As to dealing with fungus and diseases, I just try different things and see what seems to work best. I don't dig very much and just keep heaping on the compost and other organic materials. I don't think you ever really need to remove soil if all you are adding is organic material, it will just keep breaking down. My soil is sooooo much better now after only a couple of years of adding lots and lots of organic matter and keeping things moist with drip irrigation.

Beware of reading books that are not written specifically for Florida .
Seems like all gardening biology should be the same but Florida is the BIG exception most of the time .
Florida is a no-till state unless you own a patch of clay .
Other areas of the country till every year and that is the recommended and best practice .
Just as Full Sun may work in Michigan gardens - it can mean the kiss of death to some plants in Florida .
Grow locally raised plants and seeds and read locally written books .

Mary, Bill, and Michael---I will be home all day Saturday if that day is good for you, great.

Bill is asking about throwing away dirt probably because I told him that is what I do when its pure sand that I'm digging or the soil is becoming too sandy. It works for me quite well.

Christine

Saturday sounds great. Christine and DeLand Crowd: I'll be sending e-mails soon.

I've heard a couple of people tell me about throwing away or composting used up growing medium for raised beds. Lisa (I can't remember her GW handle exactly,something "Mastiff") once told me she used new soil every time she grew sugar snap peas. (I think I have that right).

A fellow who works at the hardware section of the local big box tells me he has great success veggie gardening putting down a 5-6" layer of mushroom compost and planting right in it--never digging it in. He puts down landscape timbers to keep the compost in place.

Roots can be forced to do all sorts of things (at Echo they had veggies growing on a piece of wet carpet, in a pile of smashed aluminum cans). When I was big into mulch gardening a few years ago I noticed that vegetables' roots often concentrated just below the mulch layer. Weaver's book is useful because it shows photos/drawings of what a given vegetable's roots will do under IDEAL conditions (see link).

Last spring I gave my tomatoes ideal space--deeply worked soil, and about 20 square feet per plant--and I had outstanding results--a much longer harvest than I'd had with closer spacings.

But that way of gardening requires so much space, which I do not have, not only for wide plant spacings, but for rotations and fallow periods that would be necessary to reduce disease and pest problems.

Bill

Here is a link that might be useful: A Tomato plant's roots