When you ask a Master Gardener a question about almost anything, quite often the answer will be, “It depends.” It's not that we don't know the answer, but rather that we need more information to answer correctly. This is especially true when it comes to a question about fertilizing vegetables, such as, “It's mid-season. Should I fertilize my tomato, sweet corn and bean plants?”
To answer this question, we need to know what you did before planting. If you incorporated a three- or four-inch layer of compost, then likely you don't need to fertilize now. A healthy addition of compost pre-planting will provide most of the nutrients the plants will need.
If you fertilized the soil before planting, we'll want to know what you applied and how much. Organic fertilizers are slow release and will last longer than chemical fertilizers. The latter release their nutrients quickly and may require replenishing.
We also will want to know the nutrient values of the fertilizer you used. Vegetable plants require 16 essential nutrients, the most important being nitrogen (N), phosphorus (P) and potassium (K). On a fertilizer package, the NPK content is expressed in that order, with each value representing a percentage by weight. For example, a 10-10-10 fertilizer (a “balanced” fertilizer) is 10% nitrogen, 10% phosphorus and 10% potassium by weight.
Master Gardeners welcome this kind of question because it means the person seeking advice is not just going to the garden store and purchasing fertilizer at random. At this time of year, some gardeners are prone to applying fertilizer “just in case,” an approach that can produce negative results.
Vegetable plants have differing nutrient requirements so applying the same fertilizer to all is not a good idea. What's good for your tomatoes is not necessarily good for your corn. Tomatoes seldom need additional nitrogen during the growing season. Feeding with nitrogen will just encourage them to produce excess foliage.
The only nutrient I might feed my tomato plants during the growing season is calcium, which helps prevent blossom-end rot. However, I don't add calcium unless I see that tomatoes are actually developing the problem. I sacrifice a few tomatoes by waiting, but that's preferable to adding unneeded calcium to the soil.
Sweet corn, on the other hand, requires copious amounts of nitrogen during the growing season to ensure that the ears develop fully. I never feed bean plants with nitrogen as they create, or “fix,” nitrogen in the soil rather than consume it.
Before adding fertilizer, always ask yourself a simple question: Why I am doing this? If you can't answer the question, then don't add the fertilizer.
Free Guided Tree Walk: On this fun, informational walk through Fuller Park in downtown Napa, you will learn about the park's history and get acquainted with 41 different trees. Wear comfortable shoes. Water and restrooms are available. All are handicap accessible. The book "Trees to Know in Napa Valley" will be offered for $15 each, cash or check only. . Walks begin promptly. Fuller Park is at 560 Jefferson Street in Napa. ONLINE REGISTRATION or call 707-253-4221. Walk-ins are welcome, but you can be assured of receiving a complimentary map if you register at least 48 hours in advance.
Do you want to become a UC Master Gardener of Napa County?To apply, you must attend an information meeting. The first meeting is on Saturday, July 29, from noon to 1:30 pm, at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. For other meeting dates, location and times, or to learn more about the program and volunteer commitment, visit the UC Master Gardener of Napa County website .
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County (http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
- Author: Monica Finigan, UC Master Gardener Napa County
Tomatoes are a mainstay in most summer gardens. Delicious in warm-weather salads, they are also essential to many cooked dishes. And the plants require far less water to grow than many other vegetables. Here are some tips to help ensure a successful harvest.
Wait to plant until all danger of frost is past and the soil is sufficiently warm. Cool weather makes tomato plants more susceptible to diseases and pests and slows plant growth.
Prior to planting, “harden off” tomato seedlings by placing them outside for about a week. Put them in a sheltered location, and then gradually expose them to garden conditions. If frost threatens, bring the plants indoors or cover them.
Choose stocky transplants six to eight inches tall with healthy green leaves. Check the bottom of the container. If roots are growing out the bottom, the seedlings may have been in the pot too long and may be root bound.
Water seedlings a few hours before planting and make sure the soil in the planting area is moist. Pinch off all but the top two sets of leaves. Carefully remove each seedling from its plastic pot without handling the fragile stem. Loosen the roots. Set the seedling in a planting hole deep enough to cover the exposed stem when the hole is backfilled. Those little hairs on the stem will form roots if buried and will help give your plant a good foundation.
If the seedlings are in biodegradable pots, you can plant them in the pot, but break up the pots slightly so the roots can easily grow into the soil.
Fill the planting hole with soil, press the soil firmly around the plant, and then water the area thoroughly.
Tomatoes need full sun and plenty of room to grow. If planting in a pot, choose a large one. If planting in the ground or in raised beds, space seedlings 24 to 30 inches apart. If you don't intend to stake or cage them, they will need even more room.
Most tomato plants benefit from some type of support. Cages or stakes keep them off the ground, maximize space and make harvesting easier. I like the rectangular wire cages that collapse for winter storage.
Place cages around seedlings soon after planting to avoid damaging the plants. Insert two strong stakes on both sides of the cage to provide support when the plant becomes heavy with fruit. Check the ultimate height of the variety you are planting to determine the height of the cage you need. The openings in the cage should be large enough to accommodate your hand at harvest time.
If you prefer to stake your plants, select stakes six feet long and one and one half to two inches wide. Drive them one foot into the soil four to six inches from the plant. As the plants grow, pull the stems toward the stakes and loosely tie them at intervals of ten to twelve inches. Use strips of cloth or other flexible material. Prune the plants to a few main stems to keep them from becoming too heavy.
Tomatoes need regular watering. Fluctuations in soil moisture can promote fruit cracking and blossom-end rot. Keep the area weeded. Weeds compete with your tomatoes for nutrients and water and can harbor pests. A three- to four-inch layer of mulch will minimize weeds and help retain soil moisture.
Don't fertilize until the plants are flowering and fruits are forming. Too much nitrogen fertilizer in the beginning will encourage green growth but will delay fruit formation. Once the plants start fruiting, give them a nitrogen fertilizer every four to six weeks. Follow the instructions on the label. Place the fertilizer alongside the growing plants in shallow grooves or on the soil surface. Water it in thoroughly.
Harvest tomatoes when they reach full color. Store at room temperature—not in the refrigerator—to enjoy their flavor at its best.
Tomato Plant Sale: U. C. Master Gardeners of Napa County will hold their fourth annual Tomato Sale and Education Day on Saturday, April 23, from 9 a.m. until sold out, in a new location at 1710 Soscol Avenue, Napa. Choose from 28 varieties, including heirlooms and new varieties in a range of colors. These healthy, Master Gardener-grown seedlings include types for fresh eating and for sauce.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.