For Good Plants, Good Soil - Marion County
To Grow Good Plants You Need Good Soil
By Steve Mayer
Extension Educator-Horticulture
Purdue Extension-Marion County
Soil provides plants with food and water to help them grow. It is the foundation for a productive vegetable garden and a beautiful flower garden. To grow good plants, you need good soil.
The first step to improve your soil is to take a soil test. Soil testing is the only way to tell what your soil really needs.
Applying too much fertilizer could be detrimental to your plants. You could waste money or pollute the environment. Adding too little fertilizer or the wrong fertilizer could produce poor results.
Test your soil pH and nutrient status every 3 to 5 years. The pH is an indicator of the degree of acidity or alkalinity. It influences nutrient uptake by the plants. Phosphorus and potassium are the most important nutrients to measure. The percent organic matter will give an indication of the physical structure of the soil.
Proper soil sampling techniques are important to obtain accurate soil test results. Purdue Extension publication HO-71 entitled Collecting Soil Samples for Testing provides specific advice on how to take a proper soil sample. A commercial soil testing lab will provide more accurate results than a soil test kit.
Plan to add fertilizer prior to planting your vegetables or flowers whether you test your soil or not. Nutrient levels may decrease over time due to harvesting vegetables and/or nutrients leaching out of the root zone from rain or irrigation.
The three numbers on fertilizer bags refer to the percent in weight of available nitrogen, phosphorus (phosphate) and potassium (potash) in that order. The best fertilizer analysis depends on your specific soil. However, gardens generally respond well to high phosphorus (such as 5-10-5) or balanced complete fertilizers (such as 12-12-12).
One pound of actual nitrogen (N) per 1000 sq ft is a typical fertilizer rate but it may be varied depending on the situation. At this rate you would add 20 pounds of 5-10-5 per 1000 sq ft (2 pounds/100 sq ft) or 8.3 pounds of 12-12-12 per 1000 sq ft (0.8 pound/100 sq ft).
One pound of a typical dry fertilizer for the home garden is roughly equivalent to 1 pint or 2 cups or 96 teaspoons. You can use this fact for fertilizing small areas. At the one pound of N per 1000 sq ft rate, you would apply about 2 teaspoons of 5-10-5 per sq ft or about 1 teaspoon of 12-12-12 per sq ft.
Depending on the plant, additional fertilizer may need to be applied every 4 to 6 weeks during the growing season. One half of the typical rate will often suffice. This applies to quick release fertilizers. Slow release fertilizers may be needed less frequently or once a season.
For all vegetable or flower transplants, apply a water soluble starter fertilizer at the rate recommended on the package. This will give a quick start to new transplants.
To improve the physical structure of the soil, add organic matter prior to planting. It improves the water holding capacity and nutrient holding capacity of the soil. You can use compost, manure, peat moss or other organic materials.
Clay soils need at least 4 to 5 percent organic matter for best plant growth. This usually requires applications of organic material each year to reach and maintain these levels.
Thoroughly incorporate organic matter by spading or tilling. Work at least 6 to 8 inches deep. However, do not work the soil while it is too wet. This will destroy the delicate soil structure and make the soil hard and cloddy. It is dry enough to work if you can crumble a soil ball with your fingers. If it clings together, it is still too wet.
If you really want to have good soil, consider double digging. This is a process by which you dig twice as deep one row at a time. First you improve the top foot of soil with organic matter and set it to the side. Then you improve the second foot of soil the same way. It is very labor intensive but highly beneficial to the growth of plants in the long run.
Questions
Q. Who can I contact for more information on soil testing?
A. Purdue Extension-Marion County has information on how to sample your soil and where to get it tested. Call 275-9292 or e-mail.
Q. How can I make my own compost?
A. Information on how to make, manage and use compost is available in Purdue publication ID-182.
Steve Mayer is Extension Educator-Horticulture with Purdue Extension-Marion County. He coordinates the Master Gardener program in Marion County. To contact a Master Gardener, call (317) 275-9292, or e-mail: marionmg@purdue.edu
Photo Credit: Steve Mayer
Purdue University, Indiana Counties and U.S. Department of Agriculture Cooperating. An Affirmative Action/Equal Opportunity Institution.
February 2004
