Vegetable Gardening (107 page)

3. A week or two before planting, water the entire area with a hose or sprinkler so it's wet to 6 inches deep.

Roll out the plastic over the planting area and cover the edges of the plastic with soil.

4. Cut holes in the plastic where you want to plant your transplants.

You can sow seed this way as well; just make sure that the seed can get through the holes in the plastic after it germinates.

5. Plant your seeds or transplants in the holes.

Make sure you plant in wet spots; otherwise, the plants may not get enough water.

If you live in a climate that gets very hot in the summer (Texas, for example), after the weather starts to warm, you may want to cover black plastic with an organic mulch to prevent the soil from getting too warm. Or consider using white plastic instead.

Unless you have a problem with the irrigation system, you usually don't have to remove the plastic until the end of the season.

Other inorganic mulches

Beside plastics, you also can use the following inorganic mulches in your vegetable garden:

Cardboard:
Even though it's biodegradable, cardboard takes so long to decompose that I treat it as an inorganic mulch. You can cut cardboard boxes to fit in pathways. If you don't like their look, cover them with hay or straw.

Landscape fabric:
This inorganic mulch doesn't warm the soil as much as black plastic, but it's permeable, enabling you to water through it. It also does a good job of keeping down weeds. You can find landscape fabric at your local nursery. You apply landscape fabric the same way that you do plastic (see the preceding section).

Rug strips:
Roll out 3-foot rug strips and place them nap side down, leaving about 6 inches of open soil between strips for irrigation and planting. Even though rug strips look pretty weird in a garden, they keep the weeds down and make a nice path.

Deciding which mulch to use

Choosing a mulch and deciding when to use it in your vegetable garden depends on the type of vegetables that you grow and when you plant them. Check out these mulching tips for different types of vegetables:

Cool-season vegetables planted in early spring:
You want the sun to warm your soil in the spring because lots of sun helps young plants get off to a fast start. Here are a few mulching pointers for these vegetables:

• Lay down organic mulch when the soil starts to warm and when the plants need regular water. If you mulch too early, the soil stays too cold and wet for proper root growth.

• In areas with short growing seasons, you can plant broccoli, cauliflower, and cool-season plants through plastic. Cover the plastic with organic matter when the weather warms to keep the soil cool.

Cool-season vegetables planted in late summer or early fall:
With these vegetables, you want the cooling effect, so put down an organic mulch right after planting. Here are a few other things to keep in mind:

• When the weather starts to cool, rake off or remove the organic mulch so the soil warms.

• You can plant through plastic late in the year, but you should cover it with an organic mulch immediately so the soil doesn't get too hot. Then remove the organic mulch when the weather cools and let the plastic warm the soil through harvest.

• Many root crops can be stored in the ground well into winter if you cover them with a thick organic mulch like straw. Applied before the ground freezes, the mulch keeps the soil loose and unfrozen so you can dig the vegetables later into winter.

Warm-season vegetables planted in spring:
With these vegetables, keep the ground clear if you're planting really early — the more heat the better. Planting through plastic works in early spring. In hot climates, apply an organic mulch when the weather starts to get really warm in summer.

Determining Important Nutrients Your Soil Needs

Sixteen elements are essential for healthy plant growth. Of these elements, plants especially need carbon, hydrogen, and oxygen in large quantities. They also need energy from sunlight for
photosynthesis,
the process by which plants use carbon dioxide from the air and water from the soil to produce sugars that enable them to grow. Nature — and your conscientious watering — supply these elements.

Plants also need nitrogen, phosphorus, and potassium in relatively large quantities. Plants take up these three nutrients — often called
macronutrients
— from the soil. If your soil doesn't contain enough of these nutrients, you can supply them by fertilizing, which I discuss in detail later in this chapter.

The following sections list important nutrients that your plants need, along with information to help you determine when you need to add nutrients to your soil. To find out what quantities to add, refer to the chapters on individual vegetables in Part II. (Chapter 14 has details on soil pH and pointers on performing soil tests.)

Macronutrients

Nitrogen (N), a key component of proteins and
chlorophyll
(the plant pigment that plays a vital role in photosynthesis), is responsible for the healthy, green color of your plants. Nitrogen is a volatile creature; it easily moves around in the soil and can leach away from plant roots as a result of rain or watering. Therefore, you need to be sure that your plants receive a steady supply of nitrogen all season long.

How to detect too little:
Plants with a nitrogen deficiency usually show yellowing (in older leaves first) and slowed growth. However, with plants like tomatoes, a nitrogen deficiency may first appear as a reddening of the stems and the undersides of the leaves.