Your gardens in 2019 will be no better than the soils you prepare for them. Whether it’s flowers or vegetables, it all starts with the bed preparation, and the time to rev up those engines is at hand.
You say to yourself, “But Neil, you’re rushing things. It’s still the middle of winter. How can it possibly be time to be working the soil?” That’s because more than half of our vegetables and many of our flowers need to be planted while it’s still cool – weeks before the average date of our last killing freeze. Timing is critical, so let’s outline the steps to success.
No matter what type of soil you have in your neighborhood, be it sandy or clay, the best way to improve it is by adding several types of organic matter. It will help sandy soils hold moisture and nutrients, and organic matter will break heavy clay soils into small clods that allow better movement of water and fertilizers through the soil.
There are several good sources of organic matter. When I’m preparing my own garden soils I’ll add a couple of inches of sphagnum peat moss and one inch each of well-rotted compost, finely ground pine bark or hardwood mulch and well-rotted manure into the top foot of topsoil. Topsoil vendors have several blends of organic matter that they sell in bulk, often from recycled yard waste.
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If I’m working with clay topsoil I’ll add 1 inch of expanded shale soil conditioner as well. It’s a clay-based material that has been heated until it has popped. Research from Texas A&M about 20 years ago showed it to loosen tight clays much better than the washed brick sand we used to recommend.
I found many years ago that a rear-tine rototiller does by far the best job of blending all of these materials together into the topsoil. However, as a side note, if you have turfgrass in the place where you’re going to be preparing the soil you’re going to have to get it out of the way manually before you crank up the tiller. There is no weedkiller to use at this time of the year. Use a flat-bladed nursery spade pushed in almost parallel to the ground to remove the sod and around 1 inch of soil.
The preparation I’ve described will leave you with a soil mix that is almost of the consistency of potting soil. Rake out the roots, rocks and any other debris from the soil. If the area where you’re creating this garden stands in water after heavy rains take steps now to improve its drainage. Build raised beds by mounding the soil with your rake, tapering it down to the edges. If you prefer finished sides to the beds you can use edging, river rocks, bricks or concrete edging stones as your boundaries. If you can create 3 or 4 inches of elevation above the surrounding grade your plants will benefit greatly during extended wet weather.
Since organic matter does decay over the months and years you will have to replenish the supplies. You’ll have access to most garden plots at least a couple of times each year – once in the summer as your spring flowers and vegetables finish, and once in the winter after the fall crops have been removed. Add in one-third to one-half the original amount of organic matter and rototill back to the original 12-inch depth. Incorporate additional expanded shale every four or five years.
You ought to have your soil tested every three or four years to monitor the changes in retained nutrients, accumulations of mineral salts and other factors that could impact the growth of your plants. Several local nurseries offer soil testing in the springtime. Texas A&M also has an outstanding testing lab that is used by farmers, ranchers and commercial growers. Luckily, it’s also available to us home gardeners at affordable pricing as well. The form you’ll want to fill out is available from their website (http://soiltesting.tamu.edu/files/urbansoil.pdf). See the form for complete sampling and mailing instructions.
I’ll warn you of one surprise you’ll probably encounter. Most Texas soils are already high in the middle number of the fertilizer analysis, that being phosphorus. It dissolves very slowly, so it tends to accumulate in our soils, especially clays. Excessive phosphorus can affect how well our plants take up minor nutrients and in that process the phosphorus can take on almost toxic effects. Phosphorus is critical to the production of flowers and fruit, but if your soil already has too much, there’s no point in adding more. So don’t be surprised if your soil test comes back showing that you should use a high quality, nitrogen-only plant food. Trust the experts.
What plants get this level of bed preparation? Annual and perennial flowers for sure. Vegetables for sure. Maybe groundcovers and small shrubs, but remember that they’re going to have to grow in the original topsoil once all the organic matter decays and disappears, so you may want to give them a reduced version of the bed prep. Medium-sized and large shrubs and trees get the native topsoil. You need to choose types that are adapted to it because they’re going to have to grow it in eventually anyway. There’s no point in babying them early on.
Excited by all this information on soil preparation? I doubt that you are. Hopefully, however, you can see its importance as you set yourself up for the gardening season ahead.