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Neil Sperry: Prep soil properly to yield growing season’s bounty

Waterlogged soils can be fatal to plants, but raising garden beds by as little as 3-4 inches will help combat the problem.
Waterlogged soils can be fatal to plants, but raising garden beds by as little as 3-4 inches will help combat the problem. Neil Sperry

You’re about to embark on a journey — one you may be on for eight months or longer. It’s called “Growing Season 2015,” and it’s unfolding even as you unfold each page of this paper.

Indeed, the first plantings of this year should go into the ground in the next several days (onions and English snap peas). But their success depends on the attention you give to preparing the soil. I have the quick steps to success.

▪ Remove existing vegetation. While you could use a glyphosate spray (with no other active ingredients) during the warmer months, your only way of removing turf and weeds now is to dig them out by hand. I use a flat-bladed nursery spade almost parallel with the ground to remove one inch of turf as I’m getting new plots ready. It’s more of a process of shoving it through moist soil than it is of actual digging.

▪ Send a soil test off for analysis. Pause long enough to gather soil samples from several areas of the ground you’ll be preparing. Mix them together for one representative test of the new bed. Information on how to collect and send the sample to the laboratory at Texas A&M is on its website: http://soiltesting.tamu.edu.

▪ Provide perfect drainage, either by planting on a slope or by using raised beds. Contrary to what you may remember, we do have periods of extended rainfall here. Waterlogged soils can be fatal to the plants you’ll be growing, so raising your beds by as little as 3 to 4 inches can be a huge help. Use wood for short-term beds, or large river rocks or edging stones for a more permanent boundary.

▪ Determine the type of soil that you have. Most of the Metroplex is built on heavy black clay “gumbo” soils. Perhaps 5 percent of DFW’s Mid-Cities area is on a strip of red, sandy, clay loam soils. The amendments you’ll add will depend to a large degree on the type of soil that’s native to your area, as you’ll see next.

▪ Add organic matter to improve any soil. The list includes sphagnum peat moss, well-rotted manure, compost, finely ground pine bark mulch and shredded tree leaves, among others. The best approach is to use a mixture of all of these, and to add a cumulative total of 5 or 6 inches. Some types (shredded tree leaves as the best example) decay quickly, while others like pine bark mulch take much longer.

It’s the process of decaying that allows the organic matter to loosen clay soils for far better root growth. And, from a completely different perspective, that same organic matter mix helps sandy soils retain moisture and nutrients better.

▪ Expanded shale is the newest player in the game. We used to recommend adding 1 inch of “washed” brick sand (as used in making mortar) when we were working with a heavy clay soil, but research done by Texas A&M over the past 15 years has found that expanded shale works far better.

It’s a clay-based material that is heated to high temperatures. In the process, it dries and hardens into a porous and reasonably permanent (up to 10 years) material. When I’m working up new flower and vegetable beds, I’ll add 1 inch of expanded shale along with the 5 or 6 inches of organic matter.

▪ Rototill to blend all the materials together, and till to a depth of 12 to 16 inches into the native soil. Rear-tine tillers work best. You should end up with a planting bed that feels like high-quality potting soil after it’s all been rototilled and blended. Tilling that deeply will help the improved soil accommodate root growth of all types of flowers and vegetables, large and small.

▪ Mulch, and then mulch some more. Mulches help every planting. They moderate the rate of soil temperature changes, retard development of weeds and lessen the likelihood of runoff and erosion. In addition, they keep low-growing flowers and fruiting and leafy vegetables out of direct contact with the soil, and they greatly reduce splashing and the subsequent spread of soil-borne diseases.

To say the least, mulches pay big dividends.

There are various types of mulches, each with its own advantages. That same pine bark mulch you used as a soil amendment can also be used as a mulch across the top of the soil. The nickel-and-dime-sized pieces will lay flat, and they can be worked into the soil each time that you rototill between subsequent crops.

Other people use pine straw, compost and even old newspapers (garden sections are especially inspiring to your plants). And many of us use roll-type weed-blocking mulches that can be cut to fit between rows and around plants within the rows. They’re also quite useful with plantings of shrubs.

Garden soils are like the foundations of our houses: our gardens will be no better than the soils we prepare for them.

Neil Sperry publishes Neil Sperry’s GARDENS Magazine and hosts “Texas Gardening” 8-10 a.m. Sunday on WBAP 820AM. Reach him during those hours at 800-288-9227. Online: http://neilsperry.com.

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