The Garden Patch: What do you feed a hungry garden?

042415-FertbagThis time let’s talk about how much fertilizer your hungry garden wants and needs and let’s start with …

Calculating the amount of fertilizer needed for an area

Consider the recommendation for the particular nutrient needed and your soil analysis.

If you need to add 0.1 pound of N (nitrogen) per 100 square feet and you have 10 – 10 – 10 fertilizer, which contains 10 percent N, you will have to add one pound of this material per 100 square feet to achieve the needed amount of N.

The relationship of N, P (phosphorus) and K (potassium) to each other, sometimes referred to as the ratio, indicates the proportion of each element. For example 1-1-1 means there are equal proportions of N, P and K as does 10-10-10. However, a 2-1-1 ratio means there is twice as much N as P or K as is true with 10-5-5. The ratio does not indicate the weight of the elements in the fertilizer bag, but only their relationship to each other.

In addition to N, P and K, 10 other elements that plants require come from the soil. Generally, it is not necessary to add these elements as they are present in sufficient quantities in Kansas soils. However, an occasional addition of one or more of these micronutrients may be required.

Here’s how to figure it out

Measure the area of your garden. You need total square feet. Determine the nutrient you need to add per 100 square feet.

Suppose your test results indicate that you need 0.1 pound N, 0.1 pound P and 0.05 pound K. Multiply the amount you need by the number of hundred square feet units in your garden. For example, if your garden is 200 square feet, you would need two times the amount indicated above or 0.2 pound N, 0.2 pound P and 0.1 pound K. Sound like Greek to you? Read on …

Because you need (in the above example) equal portions of N and P but less of K, look for a fertilizer that may have the ratio of nutrients in this range. You may not be able to find a fertilizer that provides exactly the ratio you need, so try to get as close as you can.

For example, it you find a fertilizer that has 10-10-5, this would provide the exact ratio you need. To calculate how much of this material to add, divide the amount you need by the nutrient concentration or analysis of the fertilizer and multiply by 100 because the analysis represents a percentage or fractional value of 100. Don’t hesitate to ask your supplier to assist you with this calculation!

Most fertilizers you find are complete fertilizers with proportions of each major fertilizer element. Some sources supply specific concentrations of a single element only.

Applying fertilizers

Row applications are the most efficient application for row garden crops. As a general rule, use about 1 to 2 pounds of balanced analysis fertilizer per 100 feet of row. The best method of applying fertilizer is to dig a small trench 2 to 3 inches deep on either side of a row before planting. Sprinkle half the amount of fertilizer in each trench. Cover the trenches and plant in the marked row.

An undesirable feature of row application is that it requires a lot of WORK. If you do not want to apply fertilizer to each row, you can broadcast or spread fertilizer throughout the garden area. Use 2 to 3 pounds of fertilizer per 100 square feet, spread uniformly over the surface, and incorporate into the soil before planting.

For tomatoes, cabbage or other transplanted crops as well as for melons or cucumbers planted in hills, use about 2 tablespoons of fertilizer placed 2 to 3 inches below the roots or seeds. Again, after placing the fertilizer, cover with soil and plant as usual.

Starter solutions

Starter solutions are used for transplanted vegetables such as tomatoes, peppers, eggplant or cabbage, and should have a starter fertilizer added to the water used in setting the plants to help get them off to a faster (and stronger) start. Commercial starter fertilizers mix with water or are water soluble. Follow label directions, because mixing too much starter fertilizer can burn the plant roots.

You can make your own starter fertilizer solution by adding 2 tablespoons of ordinary fertilizer, such as 5-10-10, 3-12-12, 10-10-10 or similar material to a gallon of water. Mix well. While some of the larger fertilizer particles will settle out, enough soluble material will remain in the water. Use about 1 cup of this starter solution for each plant. Commercial soluble fertilizers also can be used as a plant starter. FOLLOW LABEL DIRECTIONS!


Nitrogen often leaches or washes out of the reach of plant roots, particularly in years when rainfall is abundant and in sandy garden soils. A side dressing is simply an application of a nitrogen-containing fertilizer alongside a row of growing plants. Apply when corn is 12 to 18 inches high, after first fruits have set on tomatoes, or when plants lack a healthy, dark green appearance.

It is possible to apply too much nitrogen; use fertilizer sparingly. Use 1/4 pound of ammonium nitrate or 1/5 pound of urea per 100 feet of row. If these materials are not available, use an ordinary balanced fertilizer such as 5-10-10, 8-16-16, or others at the rate of 1 to 2 pounds per 100 feet of row. Don’t put fertilizer directly on the plant foliage and, when possible, water after applying the fertilizer.

Foliar feeding

Foliar feeding may be done in an emergency. It means adding certain nutrients to a plant by applying them to the plant foliage when nutrient deficiency symptoms develop. It is advisable to make every attempt to add the necessary nutrients to the soil before the symptoms develop because foliar application should be used only as an experimental or emergency treatment. Unless the soil conditions causing the symptoms are corrected, the problem will reappear soon!

Using a commercial wetting agent or a few drops of detergent in the solution provides better coverage of foliage. Apply sprays in early morning or late afternoon on a cloudy day or soon after a rain. Mixing these elements with one another may be difficult. Do not attempt to mix foliar nutrients with pest control sprays!

I hope everything is well with you and your garden and that you’ll have a bumper crop come harvest time! Till next time!


stevehallerSteve Haller, of Osage City, a K-State Research and Extension Master Gardener, writes The Garden Patch, featuring gardening ideas and tips for gardeners in northeast Kansas. In his words: “I am not a horticulturist. By education I am an economist. By experience, I am a marketing guru from a local to an international scale. Gardening was taught to me by my grandfather and my mom, and I’ve been doing it since World War II was going on.”

Steve can be contacted at [email protected], or leave questions or comments below.

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