What’s Wrong with Vegetable Garden Soil
Question from Pat:
I have had alot of disease in the veg garden this year- the tomatoes plants turned brown before hey set fruit- the corn had aphids and ants. I have been doing 3 crops a year for 10 yrs- what can I do to restore the health of the soil.
Answer from Pat:
The first time a person grows vegetables they almost always have “Beginners Luck”. The first year you plant crops everything goes great. The only pests you have are a few click beetles. The rest of the pests haven’t yet found your garden.The second year the pests all say “YUM!” and move in. The third year they bring their family and friends. The following year diseases set in as well.
But don’t worry. There are solutions to all these problems. Growing a truly organic garden is the path to plant health. I did this for many years and never had the problems I hear from others. One of the most important thing to do is always to rotate your crops. Don’t plant them in the same place twice because pests and diseases that favor certain crops will build up in the soil. Try not to plant a crop in the same place twice for three years and four is even better. I’m not going to talk about your tomatoes here since I have covered tomato problems in a video on this website. Please see that and also read the various posts on tomatoes and on tomato pests and diseases on this site.
The main key is healthy soil. If you plant three crops a year then you amend the soil three times a year. Every single time you replant a bed, first dig up and turn over the soil and then spread a layer of well-rotted, homemade compost or bagged or trucked compost on top and dig that into the top 8 to 12 inches of ground. Rake the bed flat again. Then add organic fertilizer according to package directions and work that into the top 6 inches of the soil. Rake that flat. Water it with and inch or two of irrigation, let it settle overnight and the next day plant your crops.
Another way to go is to top the soil annually with manure (horse manure from a good horse owner who picks up daily is what I recommend.) I knew a gardener in an interior zone who grew magnificent vegetables and flowers. She lived in an interior climate zone where it got too hot in August to do much outdoors except in the early morning and the evening. By August her vegetables were winding down, but she was still harvesting some. She topped the ground all around them with a truck load of cow manure she got from a dairy near her house where the cows were out in a field and she knew the owners and the cows got no hormones. In October she dug the manure into the ground. By then it was aged enough and she planted her flower garden and her veggies in October. In spring she amended the beds again, this time with compost before replanting with summer crops and summer flowers. Meanwhile she was growing transplants from seeds planted in flats. She planted all her beds from seeds, bulbs, and transplants she had grown.
You don’t need to plant three times a year. I think that’s part of your problem. Just plant twice a year and each plant in its right season, warm-season crops in spring and cool-season crops in fall and winter. For example, onions and strawberries in November, and melons in May. Just follow my book it tells you just when to plant each crop. My method always has been to plant vegetables just twice. This enables one to have a complete cleanup of the garden and to dig up and turn over the soil and amend the soil twice a year in February and September. You would be surprised how many pests and disease problems you get rid of by following this plan. You dig most of them under the ground. You compost a bunch and you start out clean. Garden timing is also important. Plant the warm-season crops in March, April, and May, depending on what you are planting. Plant the cool-season crops in September, October, and November, again this depends on what you plant.
The complete cleanup I suggest also prevents ants from setting up housekeeping permanently in your beds. That is something you cannot allow. After your complete cleanup as I have suggested and amending the soil, fertilizing and planting. When plants are up and growing, release lady bugs to eat the aphids. Follow the method in my book for releasing them. Chill them in the refrigerator and release them into a moist watered garden, low on plants as described and explained on page 160. For more on ladybugs and beneficials read pages 44 and 45, 85—86,119,160, & 247. Additionally put a layer of earthworm castings on top of the ground. This will get rid of ants. You are right. Ants carry in the aphids, but good organic garden won’t have aphids due to all the beneficials killing them.
Also the more organic your soil becomes, the fewer disease problems you will have because good fungi will abound in the ground and they kill the bad fungi. If there happens to be a winter or summer when you can’t grow vegetables for one reason or another, plant a cover crop. For example in fall you could plant crimson clover and after it blooms in spring, dig it into the ground. Two weeks later you can plant. Or in spring plant alfalfa and in fall dig that into the ground. Both are legumes and will add nitrogen as well as improving the tilth and making the soil look beautifully black and fertile.
Pat,
I live in Thousand Oaks, where the soil is very alkaline. I have a steep southwest facing hillside where I’ve constructed raised vegetable planters using stone blocks (the kind you see for retaining walls and such). The soil in the planters is mostly imported- the only native soil in there is whatever comes up when I rototill in the Spring. We amend and pH adjust the soil every spring.
Here’s my problem- everything does well until about July/August/September, when everything in the beds gets very sickly looking. Tomatoes, eggplant, beans, etc.; it all gets sickly and doesn’t do well. I’ve tried lots of things, but here’s my current theory (which I would like your opinion on). During the hot months, the veggie garden can get very very hot. It’s about 10 or so degrees hotter than the prevailing temperature due to the heat radiating from the stone blocks. I think these stone blocks are heating up and consequently heating up the soil in the planter to a degree that the plants don’t like it. Even well after the sun goes down, the blocks are warm to the touch.
So my question is- what would the manifestation of the soil being too hot be on my veggies? Do you think this is a reasonable theory? Thanks
My first recommendation for you is always to stick with the planting dates recommended for Southern California, which means begin putting in the summer vegetables on the first of March, (though of course wait for April or May to plant cantaloupe and other hot-weather lovers), and in fall begin planting winter vegetables in September and October. This arrangement means that you will pull out your winter vegetables in spring and will have harvested out many of your summer crops by the beginning of August. Many gardeners in hot interior gardens tell me their crops are pretty well fried by August anyway.
That said, the effect of hot sun hitting the side of a container is a well-known problem. This effect is at its worst when a container is porous like, for example, a terra cotta pot or a concrete block, unless it is well-coated inside with waterproof material, such as black tar. Even then, the supposedly waterproof coating may wear thin or get holes in it and water may escape between the cracks of the blocks. When water escapes from the walls of a dry container, roots will follow and will create a mat around the inside of the walls of the container often winding round and round. This does not happen with plastic containers, which aren’t as aesthetic as porous terra cotta but actually work better for growing plants, since roots are evenly distributed inside them. If that is happening with the roots inside your concrete block walls, yes indeed they can be fried by sun and the result is root damage that can kill or set back plants. I often suggest to gardeners who grow plants in containers that they plant their specimens in plastic and then double-pot the plant by sinking the plastic pot into an ornamental container that will shade interior container.
Additionally, the heat can build up in the soil simply by being above ground in a hot climate. The American Indians of the Southwest found that many times their crops grew better when planted in sunken beds instead of raised beds. They dug out these beds and filled them with manure and organic matter to hold moisture and give nutrients and planted down in these sunken beds and crops stayed cooler, retained moisture longer, and did much better. They also often buried an earthen pot in the ground next to plants and filled the pot with water, the water slowly seeped out into the surrounding soil. Called “pot irrigation”, this proved highly successful in hot climates. Alkalinity in soil is a problem with all soils in dry climates but can be corrected by adding massive amounts of organic matter. Concrete blocks are also highly alkaline and leaching of alkalinity from the blocks could be part of your problem.
Here are my suggestions for curing your problem: It would be best to waterproof the inside of the blocks but I don’t suppose you want to dig out your beds. So short of that I would paint the outside of the concrete blocks (tops and sides) with bright white paint such as elastometric roof paint. This paint was designed to cool roofs and it is waterproof. There is also one type of paint that bubbles up,like a layer of insulation. This is meant for roofs also but I think would do a lot to fix your problem. You would be insulating your concrete block walls against the heat and this would help to cool the soil. Mulching any soil that is hit by sun can also help cool the soil.
It would also help to provide some shade for your summer vegetables in the afternoon. Though vegetables don’t grow in shade, I nonetheless know of some gardeners in hot interior climates who have used cheap patio umbrellas on stands to shade the sides of raised beds from burning sun in the afternoon when sun is hottest. This technique enabled one gardener to grow lettuce all summer and it did not go to seed. This gardener allowed her lettuce and a few other vegetables to have sun in the morning and then rolled over the umbrellas in the afternoon or permanently placed them where they provide some shade in the afternoon. You might also try shade cloth on sticks. Wind might be a problem, but umbrellas can be weighted or tied down firmly so they don’t blow over in wind. I do that at my house. Tall crops such as corn can also help provide some shade from the west in the afternoon. A southern exposure is great for sunshine and recommended for tropicals. (You should be able to grow great bananas if it doesn’t freeze in winter and if you can provide adequate water.) Full sun is great for veggies, but I can see in your case you might need to mitigate this in mid summer by adding some shade.
Another thought: If you get foliage or cloth, such as shade cloth or umbrellas, wet by misting it with water, you can effectively cool the air by at least ten degrees, often more. You would have to install a system of misters on a time clock to do this. The San Diego Zoo has used misters attached to tall trees for many years to cool hot air in summer for some plants and animals. This system does not use as much water as one might think.
A final thought: Cantaloupe, watermelon, and winter squash (which despite the name is a summer vegetable) all need heat but these plants make so much foliage they will hide the side of your beds and cool the soil.