This weekend, I plan to fertilize all the shrubs and trees in my yard.

To understand why a winter fertilization is beneficial, you should realize that roots put on most new growth during the dormant season. Even though the top growth is inactive, the roots are growing and taking in nutrients. These nutrients will provide the raw materials for spring stem and leaf growth.

Some people are afraid to fertilize in winter because they have heard that fertilization late in the growing season causes winter injury. I agree that the worst time to fertilize is in fall before the plants become dormant. September and October fertilization with nitrogen will trigger new growth on many shrubs. This new growth right before winter is bound to be killed. You should not apply fertilizer until deciduous plants have dropped their leaves and evergreens have stopped producing new growth.

When you choose a fertilizer to use on trees and shrubs, look at the three numbers on the fertilizer bag. The first number stands for percent nitrogen, the second for percent phosphorus, and the third for percent potassium. There are 16 essential elements that plants need, but these three are used in the largest amounts. A good fertilizer for trees and shrubs should have a high first number. This number, which indicates nitrogen content, should be two to three times as large as each of the other two numbers.

I like a fertilizer that has some slow release action. These can be recognized because they will have a release time on the label. I like to use Sta-Green Nurseryman’s Special which has an analysis of 12-6-6 and a slow release formulation. Fertilizers such as 8-8-8 or 13-13-13 are salts that are quickly available, quickly leached from the roots, and likely to burn the plant. The slow release fertilizer causes even growth over a long period of time and is less likely to burn. Slow release fertilizers are a little more expensive, but I think they are worth the money.

Organic fertilizers such as cottonseed meal are also considered to be slow release. An additional benefit of organic fertilizers is that they improve the soil. If you have soil that is less than desirable, consider using organic fertilizers to feed the plant and the soil. Cottonseed meal is available at agricultural supply stores and is often sold as animal feed. It is inexpensive and can be used on any plant. If you decide to try cottonseed meal, use the whole bag or seal it in an airtight container to prevent spoilage.

In addition to the Nursery Special and cottonseed meal, I plan to apply an iron supplement to any acid loving plant (azalea, camellia, blueberry, gardenia, mountain laurel, etc.) that looks yellow. Iron sulfate or Copperas will correct the problem. I sometimes also use a fertilizer called Ironite that has iron and other nutrients.

An annual fertilizer application is especially important for plants under stress. Fertilizer can help a tree to heal wounds or replace leaves lost from insect damage. I have a large white oak that has suffered lightening damage and a tree surgeon recommended fertilizer as part of the treatment program.

If you are fertilizing this time of year, remember that winter is a bad time to fertilize turfgrass. In Mississippi, turfgrass may never go dormant so winter fertilization should be avoided. The best month to fertilize your lawn is May.

The best time to apply fertilizer is when the ground is reasonably moist and when more rain is expected. We have had a good bit of rain this winter and more is in the forecast. Hopefully the weather will cooperate this weekend so I can sling some fertilizer!



• Gail Barton is Meridian Community College’s program coordinator for the Horticulture Technology Program. She is also the author of a gardening book.