Vegetable Gardening Read online

  Try to use soaker hoses and drip irrigation to direct water to the plants and not waste it on pathways. Use a timer to turn on the system during cool parts of the day for only as long as needed.

  Collect rainwater from roofs and store it to be used in the garden. In some areas you can even use gray waste water from your home in your yards. Check with your local water municipality for regulations on using gray water.

  For more ways to save water while maintaining your gardens and flower beds, check out Sustainable Landscaping For Dummies by Owen Dell (Wiley).

  Keeping Your Plants Cozy and Weed Free with Mulch

  Mulch is any material, organic or inorganic, that you place over the surface of soil, usually directly over the root zone of growing plants. It has many benefits depending on the type used. Mulch suppresses weeds, holds in moisture, modifies soil temperature, lessens the chances of certain diseases attacking your plants, and adds an attractive look to your garden.

  Some people use compost as a mulch, but you have to remember that compost has a different purpose than mulch. Compost is added and mixed into the soil to add nutrients and increase the workability of soil (water-holding capacity, aeration, and so on). Mulch generally doesn't add nutrients, but it helps hold in the ones already in the soil and prevents undesirables from attacking your growing plants. (You can read more about compost in Chapter 14.)

  You can choose from two basic types of mulch: organic and inorganic. For vegetable growers, each type of mulch has a unique purpose, as described in the following sections.

  Spreading organic mulch

  Organic mulch includes grass clippings, compost, leaf mold, pine needles, shredded bark, nut shells, cotton gin waste, straw hay, grain and fruit byproducts, composted manure, mushroom compost, peat moss, and sawdust. Some of these mulches are easier to find in different parts of the country. You can even use newspaper as an organic mulch; black-and-white newspaper print is perfectly safe to use in your garden, and most colored inks are soybean based and biodegradable (see Chapter 14 for more on using newspaper as mulch).

  Generally, a 2- to 4-inch layer of organic mulch, spread evenly on the ground beneath your plants, is sufficient. However, you may have to replenish the mulch during the growing season, especially in hot summer areas, because many organic mulches break down quickly.

  Using organic mulch in your vegetable garden has many benefits:

  It conserves water by reducing the soil temperature and evaporation. It also keeps the soil cool by buffering direct sunlight.

  It prevents wild fluctuations in soil moisture levels that can really spell disaster in hot weather.

  It smothers weed seeds and prevents them from germinating. Any weeds that do come up in loose mulch are easy to pull.

  As the mulch breaks down, it adds nutrients and improves the texture of the soil that it covers.

  Organic mulch looks good and makes the ground tidy and clean.

  The following list includes some of the downsides of organic mulches. As minor as they are, they may lead you to choose one type of organic mulch over another:

  Bark mulches, such as pine, are quite acidic. So if you use them, keep a close eye on the pH level of your soil and correct it accordingly. (Chapter 14 tells you how to test soil pH.) Also, the latest trend is artificially colored mulches. I'd avoid these brightly colored mulches for your veggies, because they may contain potentially harmful chemicals that can leach into your soil. Choose natural bark mulches instead.

  Grass clippings decay quickly and must be replenished often. Fortunately, grass clippings are usually pretty abundant. But if the grass goes to seed before you cut it, you may end up with grass growing in your vegetable garden. Also, make sure that no herbicides (weed killers) have been used on your lawn because the residue can damage or kill vegetables; if you have your lawn treated regularly, use another type of mulch. Likewise, hay mulch often has weed seeds in it, so use cleaner straw mulch if available.

  Some organic mulches — such as fresh sawdust — rob nitrogen from the soil as they break down. You may have to add supplemental nitrogen to your vegetables if they grow mysteriously slow or start to turn yellow. (I discuss fertilizers in detail later in this chapter.)

  Some organic mulches, such as peat moss or leaves, can pack down or get hard and crusty when exposed to weather. Water may not penetrate these mulches, running off the soil instead of soaking into the roots. My suggestion is to avoid peat moss; or at least mix it with another organic mulch such as sawdust. Don't forget that peat is also darn expensive.

  Some lightweight mulches, like straw or cocoa hulls, can blow around in the wind. You may want to avoid them if you live in a windy area.

  Organic mulch, which keeps the soil cool, may slow the growth and maturity of warm-season crops such as tomatoes and melons. This cooling can be especially problematic in areas with cool summers. However in very hot-summer areas of the country, organic mulches work to keep the roots of even warm-season crops cool and healthy.

  Composted manures may burn young vegetables if used as mulch because the manures vary in the amount of nitrogen they contain. If you want to use composted manure, mix it with three times the volume of another organic mulch before applying it.

  You can purchase organic mulches like shredded bark, compost, and leaf mold in bags or sometimes in bulk from nurseries and garden centers. Grass clippings, compost, and wood chips come free from your yard or garden.

  Laying inorganic mulch

  Inorganic mulch includes things like plastic, landscape fabric, and believe it or not, old carpet. I explain how to use all types of inorganic mulches in the following sections.

  Plastic

  Plastic is the most-used inorganic mulch for vegetable gardens. Mulching with plastic (see Figure 15-4) works best when you install drip irrigation or a soaker hose underneath the plastic before planting. Otherwise, watering is difficult. (You can place the irrigation on top of the plastic, which enables you to more easily check for clogs, but you have to run individual emitters to each plant.) Plastic doesn't work well with vegetables planted very close together, such as root crops.

  Figure 15-4: Planting in black plastic mulch.

  The color of plastic mulch you use depends on what you're growing. Some vegetables grow better with certain colored plastics. For example:

  Tomatoes, eggplants, and strawberries grow best with red plastic mulch.

  Melons grow well with dark green or IRT (infrared transmitting) plastic mulch.

  Peppers like a silver-colored mulch.

  White plastic is good for hot climates where you want to stop weeds from growing but not heat up the soil.

  Black plastic is good for weed control and warming soils. It can be used on many vegetables including cucumbers and squash.

  To mulch with plastic, follow these steps:

  1. Purchase rolls or sheets of 2- to 4-millimeter plastic (the thicker the better).

  You can find the thickness of the plastic on its label. Purchase plastic at garden centers or hardware stores, or check the appendix for sources of various colored mulches.

  2. If you're using irrigation under the plastic, lay down your drip irrigation and turn it on for several hours.

  Note where the wet spots are in the soil. Adjust the drip hose so water doesn't pool in certain areas, but is evenly distributed. See the earlier section on drip irrigation for more details on installing this type of watering system.

  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 e
nough 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.

  How to detect too much: A plant with too much nitrogen has soft-textured, dark green foliage and an underdeveloped root system, and flowering and fruiting are delayed. Too much nitrogen fertilizer, especially when plants are young, can actually burn the roots and kill them. Because nitrogen leaches out of the soil quickly, if you have too much, stop fertilizing, wait, and eventually the problem will solve itself.

  How to add it to your soil: You can supplement soil nitrogen by adding organic fertilizers, decomposing organic matter, or composted manure.

  Phosphorus (P) helps promote good root growth, increased disease resistance, and fruit and seed formation. It's less available in cooler soils, so adding a fertilizer containing phosphorus in spring is a good idea.

  How to detect too little: Plants lacking in phosphorus are stunted and sport dark green foliage and purplish stems and leaves (on the older leaves first). Soil pH affects the availability of phosphorus to plants; a pH of 6 to 7.5 keeps it available.

  How to detect too much: Too much phosphorous is a problem because it can cause zinc and iron deficiencies, and it can leach out of the soil and pollute streams and lakes. Signs of zinc or iron deficiencies appear as discolored or poorly formed leaves and reduced growth and production.

  How to add it to your soil: Sources of phosphorus include minerals, organic matter, inorganic fertilizers (such as rock phosphate), and organic fertilizers (such as bone meal).

  Unlike nitrogen, phosphorus doesn't move quickly through soil. So, add a fertilizer containing phosphorus to the root zone before planting (instead of sprinkling it on the soil surface).

  Potassium (K) promotes vigorous growth and disease resistance.

  How to detect too little: The first sign of a deficiency is slowed growth; brown leaf edges and deformed yellow leaves can indicate a severe deficiency.

  How to detect too much: Too much potassium can create nutrient imbalances in the plant and stunt its growth.

  How to add to your soil: Soil minerals provide potassium, as do organic matter and inorganic fertilizers, such as green sand and granite dust.

  Secondary nutrients and micronutrients

  Calcium, magnesium, and sulfur are known as secondary nutrients. Plants need them in substantial quantities, but not to the same extent that they need nitrogen, phosphorus, and potassium.

  How to detect too little: Most alkaline soils contain these secondary nutrients naturally, and few soils are deficient in sulfur. Most home garden soils contain these nutrients. But if you've eliminated other possibilities and you suspect a problem, a soil lab can do tests on your plant leaves to detect any deficiencies.

  How to add them to your soil: In regions where the soil is acidic, liming to keep your soil's pH in a good growth range provides adequate calcium and magnesium (the latter if you use dolomitic limestone). See Chapter 14 for more on liming.

  Micronutrients (iron, manganese, copper, boron, molybdenum, chlorine, and zinc) are elements that plants need in tiny amounts. Too much of one of these elements is often as harmful as too little.

  How to detect too little or too much: A micronutrient deficie
ncy or excess may mean that your soil is too acidic or too alkaline, so you can correct the problem by changing the pH rather than by adding more nutrients. Deficiencies and excesses most often are noted on plants that are growing poorly and through soil tests.

  How to add them to your soil: Sometimes, changing the pH sufficiently to increase micronutrient levels isn't practical, or you may need to give a plant a micronutrient quickly while you try to change the soil pH. In such cases, micronutrients are applied as chelates. Chelates are added to other chemicals, in this case micronutrients, to keep them available to plants when soil conditions are unfavorable. Apply chelated micronutrients to your soil, or better yet, spray them on plant foliage.

  Fertilizing Your Vegetable Garden

  Even if you have the healthiest soil around, growing vegetables is an intensive process that strips many important nutrients from the soil. So you need to add some fertilizer to your soil to keep it in optimum shape to feed your plants.

  How much fertilizer you add depends on the soil and the plants you're growing. So it's difficult to generalize across the board on what type of fertilizer to choose and how much to apply. Soil tests are a great way to know what to add. Refer to Chapter 14 for more on soil tests.

  Examining a fertilizer label

  Commercial fertilizers are labeled with three numbers that indicate the fertilizer's nutrient content (see Figure 15-5). The first number indicates the percentage of nitrogen (N), the second number shows the percentage of phosphate (the type of phosphorus, P2O5), and the third number represents the percentage of potash (the form of potassium used, K2O). (I explain these nutrients in detail in the earlier section "Macronutrients.")