Solarization is the only "natural" or organic way to sterilize soil. And not something that is easily done in winter. You need at least 4-6 weeks of pretty much uninterrupted sunlight and be able to generate soil temps of 140F for this to be effective. If you can start early enough in spring if weather conditions permit, you may be able to pull it off without delaying your planting season too late.

I am not convinced this is a necessarily solution to your problems, however. Edible gardens do require pretty much constant attention during the growing season and if provided diligently, pretty much any problems can be nipped in the bud before they get out of hand. If you practice proper crop rotation, plant companion plants, use row covers and other protective measures and make moderate use of organic pest controls, there should be minimal issues to contend with.

What type of soil mix did you fill your raised beds with? That can have a huge bearing on your success as well.

Along with what gardengal has said: Clean up any debris on top of the soil - remove mulches, leaves, etc... and leave bare soil. Either compost that debris, or trash it. If your soil gets dry enough to work, turn it multiple times with a few weeks between each tilling. That should help to disrupt any over-wintering pests. Rotate every crop to a new space, trying not to mix last year's soil from the same plant family to be sown this year. For example... don't put nightshades where your tomatoes were, and don't till the soil from last years tomatoes into this year's nightshade crops.

As soon as you sow, use the row covers previously mentioned by gardengal.

Much of S.C. gets pretty hot and you might be able to solarize, but as was mentioned, you'll lose time, and it might not be necessary. I might use solarization where you had soil-borne diseases, but then only on a plot that was going to be left fallow... that's just me though.

how are fungi a pest? soils without fungi are deader than Elvis. Mulches do promote bugs (and mice, and termites), but it is worth considering which bugs. I do have slugs, which are dispatched by Sluggo (organic), thus retaining the benefits of mulch. For aphids, I never have one until ladybugs go to sleep in late October. I think solarization is incompatible with truly organic gardening, and counterproductive.

Thanks for the input! I really appreciate it! I haven't found many resources so far.

So solarization doesn't seem to be the right tactic for my insect war. I don't want to sacrifice 4-6 weeks of the planting season.

I'm thinking that removing the top layer of the soil would be a good start. Any idea how deep insect eggs overwinter in soil (particularly aphids and leaf-footed bugs)? What are your thoughts on spraying the exposed layer with insecticidal soap? I'd replace the soil when I plant for the spring.

The fungi I was referring to were powdery mildew and tomato blight, both of which found their way into my garden. Do they overwinter? Would removing the top layer of soil help?

I tried a number of tactics to keep the bugs and other issues at bay, including: insecticidal soaps, neem oil, physical removal, lacewing eggs/larvae, and plants (such as oregano and mint) that supposedly deter insects. My main concern is preparing the beds as best I can for next season so I won't be sabotaged from the beginning.

Another issue is protecting the plants from exposure. My garden is in an extremely exposed area that blocks neither the harsh South Carolina sunlight or great drafts of wind I get in this area. I made A-frames out of pallets and placed them over the beds, and they were highly effective at protecting the plants, but I'm worried that they were the source of some of my bug/fungi issues. Any thoughts on whether the year they spent outside would have been enough to sterilize them or whether they might still be harboring plant assassins?

Tomato blight lives in the soil and is splashed up onto lower leaves by spring rains. Mulch as soon as you have planted them and use whatever fungal controls you can.

If it's very humid where you live, enclosing or protecting plants can encourage blights. Tomatoes need sun anyway and it helps dry out the surfaces of dew that settles overnight or rain water, which in turn helps control blight. I think. I've heard that powdery mildew and possibly other blights can be controlled with baking soda spray and/or compost tea. You might look into that.

I don't personally think removing soil and discarding it is going to make enough of a difference to make it worth losing that topsoil, although I have never dealt with leaf footed bugs. Insects and microbes are everywhere, and since you can't grow plants in a vacuum, achieving balance is the key. Keeping an eye on things and using some insecticidal soap on the aphids will help.

You didn't say what your raised beds had in them. Did you amend the soil you had, import soil, or use only compost, ...?

I can't remember the particulars about the soil we filled the beds with. It was supposed to be organic (i.e., not exposed to chemical fertilizers and the like) and I remember it being very dry, light, and fluffy. It didn't hold much water, but I have an irrigation system that maintained good soil moisture. I made a mix of worm compost, cow manure, and biochar and placed a handful in each hole I transplanted. I spread the rest in a thin layer on top of the soil.

Bugs happen - it's a fact of life :-) If one needed to sterilize the soil or remove and replace soil every time there was an outbreak of aphids or other crop damaging insects, there would be very few productive gardens in this country!

Aphids are easily controlled by hosing down with water, insecticidal soap, applications of Neem or other horticultural oils and with homemade sprays using plant extracts like garlic or citrus oil. Their eggs can overwinter in the soil but generally just disturbing the soil adequately before planting - a pretty common process with any spring garden prep - and then mulching well after planting will discourage their development. But even removing every single egg present in your garden now will not necessarily ban any aphids from returning when food sources appear. As I said to begin with........bugs happen.

Leaf footed bugs are harder to control but they overwinter as adults in weedy, brushy areas so cleaning up/mowing/cutting back any areas like this in proximity to your raised beds will help to control their populations as well. Again, removing any soil from the beds will have NO impact on these critters.

Powdery mildew does not over winter on soil. It needs plant tissue or debris to survive so if you clean up the beds properly before spring planting, you have removed the potential for any existing spores to develop. PM is much more of a climate/cultural related pathogen - it develops when air circulation is limited, in shade and when soils, air temperatures and moisture create a "perfect storm", often late season when soils are dry, temps high and with a high dew point or humidity, especially overnight. Providing sufficient sunlight, improving air circulation and making sure soils remain evenly moist during the critical periods will help enormously. Again, Neem or hort oils, baking soda mixtures and even spraying with diluted milk will help to control but these remedies need to be applied before you see signs of PM to be most effective.

Blights are indeed soil borne pathogens and soil sterilization would help to control these problems but is often so impractical that most just deal with the issues via crop rotation. And just to clarify what was mentioned above, tomatoes are members of the Solanaceae or the nightshade family, as are peppers. eggplants, and potatoes. All of these can be subject to similar blights so you want to avoid planting these in the same location season after season. In fact, it is recommended to use at least three year cycle of rotating locations for best control. You can also seek out resistant varieties as well.

Sunlight is never an enemy of a productive vegetable garden :-) It may just mean you have to water more often. Skip the A-frame pallets - they are not helping. And wind is usually not a concern either unless you get gale force ones - I live at the beach and get very strong winds off the water and they have never damaged my veggies. In fact, some veg are wind pollinated so allowing/encouraging breezes are beneficial. Winds/breezes also help to allow proper air circulation so beneficial for your PM issues.

Other than adding some fresh OM to your beds - compost, composted manure, shredded leaves, etc. - there is really nothing else you need to do before spring planting. Don't remove any soil - just work what you have together with fresh OM and you are ready to go. But expect to devote some time and attention to your garden on pretty much a daily basis during the growing season. The more time you spend working and inspecting your garden, the more proactive you can be in thwarting off problems.

A basic premise of organic growing is that a good healthy soil will grow strong and healthy plants that will be less susceptible to plant pests and diseases. So start with a good reliable soil test to be sure the soil pH is where it should be for what you want to grow and the major nutrients are in balance. Along with that soil test these simple soil test might also be of some help,

1) Soil test for organic
material. From that soil sample put enough of the rest to make a 4 inch level in
a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and
replace the lid, tightly. Shake the jar vigorously and then let it stand for 24
hours. Your soil will settle out according to soil particle size and weight.
For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the
bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above
that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole
1 foot square and 1 foot deep and fill that with water. After that water drains
away refill the hole with more water and time how long it takes that to drain
away. Anything less than 2 hours and your soil drains’ too quickly and needs
more organic matter to slow that drainage down. Anything over 6 hours and the
soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful
of your slightly damp soil and squeeze it tightly. When the pressure is
released the soil should hold together in that clump, but when poked with a
finger that clump should fall apart.

4) Smell. What does your
soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant
odor? The more organic matter in your soil the more active the soil bacteria
will be and the nicer your soil will smell, to a point. Too much organic matter
can be bad as well.

5) Life. How many
earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5,
according to the Natural Resources Conservation Service, indicates a soil that
is not healthy.

Keep in mind that it can take 3 to 5 years to create a good healthy soil with an active Soil Food Web. Soil sterilization will not do much to protect against bugs like Aphids or Leaf Footed Bugs and soil sterilization can only be done during prime growing season, mid summer, even in South Carolina. However, research has shown that soil sterilization affects the good guys of the Soil Food Web much less than myth states, although I have not found a good explanation why the good guys and gals move deeper while the bad ones do not.

Floating Row Covers may be a help here.

kimmq is kimmsr

Thanks kimmq! I'll definitely use these tests on my soil! Do you know how to test the soil pH? Can I just test the water in the shaken-up jar of soil?

I know part of my issue with the leaf-footed bugs was that I planted SO many tomato plants in one area. They grew so thickly that I couldn't reach the plants in the center of the A-frame pallets. This meant that the bugs had an abundant source of food and I had no way to reach them to spray them.

I used the pallets in part as a frame for the squashes and tomatoes to climb up - they'd grow vertically, leaving more space for other plants in the bed - but they did make it very hard to reach underneath. I'll have to look at other ways to trellis my squashes and tomatoes.

The other reason I put the pallets up is because the first set of transplants I put in the garden were annihilated in two days - they desiccated and turned to crispy, crumbly dust. From there I planted seeds directly in the garden and put pallets over them to protect them. They started out beautifully, very healthy and strong - much stockier than the leggy transplants I had initially put out. But then I got the 10 plagues of Egypt (or SC).

Every season is a lesson in what NOT to do next season! Thanks for the input everyone!

You can test pH that way using a 50/50 mixture of soil and DISTILLED water (not tap water). It is only worthwhile if you have a decent pH meter or color test kit. I would recommend spending the $ on a soil test at your local Ag Extension office or a commercial lab for the most reliable results. [Edit: That way you get NPK, micronutrients, organic matter content as well.]

If your beds are sinking a lot, the mix was very high in compost and you may need some soil in there. It kinda sounds like that if it was very fluffy and did not retain water very well.

I have extremely high proportions of Organic Material in the garden and so had roughly four inches of soil "shrinkage" this past season. The answer to that is to add more OM, so It's good I have a pickup truck that holds two and a half yards of free manure! Using that much OM kinda tames wide pH swings, making pH tests mostly unnecessary. Lots of OM, although it's a puny fertilizer, also reduces or eliminates the need to buy fertilizer. You also won't get significant fungi unless the soil's too wet.

If you worry about harsh sun (a southern fact of life) you can perhaps shade plants with other taller plants, but crispy plants aren't usually the product of failed sun screening but rather a watering problem. I shade plants in full open southern exposure only in the absolute hottest part of the summer when the temps are sustained over 100F for months, but it's a production remedy rather than a life-or-death remedy.

My biggest and best-est suggestions for heat and bugs: mulch everything until you're satisfied and then double it, add lots and lots of OM, and control your water carefully.

Organic material in soil can act as a pH buffer, although large quantities of animal manure can make the soil too alkaline. Too much manure can also increase to run off of Nitrogen and Phosphorus unless adequate amounts of vegetative waste is also put into the soil.

There are a number of kitchen chemistry tests for soil pH that give an indication of what a soils pH might be. None of those, however, provide enough information to know what to do about a soil that is not where you want it. The same with the soil test kits from your neighborhood garden center, they may tell you that the soil is acidic or alkaline but not what needs to be done to correct the problem. Soil pH is important because it does affect a plants ability to uptake, and utilize, needed nutrients.

Clemson University does soil testing for $6.00, quite inexpensive.

http://www.clemson.edu/public/regulatory/ag_svc_lab/soil_testing/

kimmq is kimmsr