There are different ways to supply nutrients, including both commercial organic or inorganic products, or by using natural materials such as leaves, grass clippings, and manures. Commercial products should list the amount, or ratio, of each nutrient on the label, most often with three numbers representing nitrogen (N), phosphorus (P) and potassium (K). However, those home-derived natural materials will vary in their ability to supply nutrients, and most of the readily available materials are low in nutrient values.
A publication I co-authored, “Selecting and Using Organic Fertilizers,” can be found on the USU Extension website at extension.usu.edu/files/publications/factsheet/hg-510.pdf. The article lists natural materials such as manures, grass clippings, leaves, etc., and their average nutrient value. It also provides an estimate of how long each takes to break down and provide those nutrients to plants.
Regardless of the often lower nutrient levels of those materials you should be adding them to your garden for their organic matter. The addition of organic materials will improve soil texture and workability, as well as overall soil health because they help increase the number of earthworms, bacteria and fungi that thrive on that organic matter – all of which are important for a healthy soil.
Each type of vegetable has its own nutrient needs, although many are similar. Be sure to adjust the amount of fertilizers you use, depending on their nutrient ratios. Since most people have already planted their vegetables I won’t go into detail about fertilizing at planting time. However, do know it’s best to apply some fertilizer then. Also, for the best initial fertilizer usage it would be advisable to do a soil test the fall or winter before you plant to determine your current potassium and phosphorus levels. For most homeowners who have regularly fertilized their gardens it is very likely you have phosphorus and potassium levels that don’t require yearly additions of fertilizer since it takes a lot of plant production to use up those two nutrients.
However, most vegetables, other than peas and beans, aren’t going to be happy with just that initial fertilization at planting and will need at least a second fertilization of nitrogen only. The fertilizer amounts listed will be based on a 21-0-0 fertilizer, meaning it has 21 percent nitrogen and no P or K. At four weeks after planting for swiss chard and spinach you should apply one-quarter cup of 21-0-0 per 10 feet of row. For most other greens, cabbage and broccoli use one-half cup per 10 feet of row. For tomatoes and peppers, you don’t want to over-stimulate leaf growth so only apply one-quarter to one-half tablespoon per plant. For vining plants such as watermelons, pumpkins, squash and cantaloupes, apply 1 to 2 tablespoons per plant after vines develop, and for cucumbers use one-quarter cup per 10 feet of row. Some vegetables want their second fertilizer dose at six weeks rather than four, so for carrots and turnips apply one-quarter cup per 10-foot row, for beets use one-quarter cup per 100 square feet, and for potatoes, use one-half pound per 100 square feet.
A few vegetables are heavy feeders and want a third feeding at eight weeks after planting. Peppers will want an additional one-quarter tablespoon of nitrogen per plant, and eggplant and tomatoes will want one-half tablespoon of nitrogen per plant.
The fertilizer amounts I mentioned are found in our extensive collection of vegetable bulletins on our website and there are others for vegetable plants I didn’t discuss. Also, I have a limited number of copies of the first edition of USU Extension’s “Vegetables, Fruits and Herbs Book,” which contains most of the individual vegetable, fruit and herb bulletins. The sale price is $8, compared to the regular price of $12.50.
Thought for the day: “It’s difficult to think anything but pleasant thoughts while eating a homegrown tomato.” —Lewis Grizzard
Previous gardening articles are available on The Times-Independent’s website, www.moabtimes.com. Have an idea you’d like Mike to consider writing about? Want more information about these topics? Call the Utah State University Extension Grand County office at 435-259-7558 or email Mike Johnson at email@example.com.