I worry that I will have disease/blight/fungus problems in the future. Before, when I was raised bed gardening, after a couple of years of intensive planting the soil became positively toxic, despite frequent amendments (but then I was not amending as well as I do now). I try to rotate crops, but with the long growing season and a small garden plot, it's difficult. Even when I'm careful, a cabbage family plant, or lettuce family, etc. is likely to wind up in same spot every year or so, and as the veggie beds are only a few hundred square feet, I'm sure the roots of all the plants spread throughout the bed--making the good of rotations questionable at best.

So, my question: veggie gardeners, is it better to amend the soil as I have been doing, or cap the soil off (that is, add a thick layer of topsoil/compost/mulch and grow directly in this new layer without spading it in), or completely replace the soil every so often the way I have seen some of you do??

Have any of you been growing veggies in the ground, in the same plot and the same soil for more than a few years and if so how do you manage?

If I grow veggies in a new layer (say 8" deep) of mulch/soil/compost every year (leaving the old soil below) will the diseases in the old soil below still reach the plants? Would putting down a thick layer of newspaper before putting down the new layer of mulch/soil/compost help stop or slow the spread of the disease, or would the plants' roots just grow down into the lower layers and catch the disease?

Or would I be better off just digging out all the soil every year or 2 and completely replacing it with a clean growing medium?

I realize this may be a controversial topic, but I'm interested in hearing different experiences.

Thanks.

Bill

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

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

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

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

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

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

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 !

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

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

Denise

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

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

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.

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.

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

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

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.

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

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