Planting, fertilizing, pruning and applying pesticides are examples of activities for which timing can mean the difference between success and failure or help and harm.

Many of you have probably used a vegetable-planting calendar of some kind.

These are handy tools for deciding when to plant so that vegetables aren’t likely to be exposed to warmer or cooler temperatures than they can handle. If you need one, N.C. Cooperative Extension has one at www.ces.ncsu.edu/depts/hort/hil/ag-06.html.

Timing is important for perennial plants, like trees and shrubs, too. If enough care is given to them (i.e., water during dry, hot weather), containerized plants can survive when planted just about any time, when you live where soil doesn’t freeze. On the other hand, bare root plants should be installed when they’re dormant, and late fall and early winter are the recommended times for planting balled-and-burlapped materials.

Before planting new trees and shrubs or anything else, we suggest taking a soil test. When you get the soil test report back, it will almost always suggest adding some nitrogen fertilizer in addition to perhaps lime, phosphorus, potassium, etc.

It’s generally best to mix needed lime and phosphorus with the soil before planting, since it takes a while for lime to cause the soil pH to rise, and most forms of phosphorus don’t readily move down into the soil when applied to the surface.

However, if you’re just planting one plant, don’t apply fertilizer with much nitrogen or potassium until the plant has sometime to get established. If you plant in the fall, just wait until spring to fertilize. If you plant in the spring, wait a month and a half or two months.

Grass should be fertilized when it’s actively growing, so that it can benefit from the nutrients that are applied. When a turfgrass is fertilized while it’s not actively growing, the fertilizer will feed weeds that are growing at that time. Also, nitrogen may leach into groundwater if there isn’t enough vegetation to uptake it.

Tall fescue is a cool season grass and should be fertilized between September and February or March. Fertilizing tall fescue after the middle of April, especially, can result in problems with the disease brown patch. Likewise, warm season grasses, like bermudagrass and zoysiagrass, should be fertilized during the warm times of the year. Carolina Lawns (www.turffiles.ncsu.edu/PDFFiles/004175/Carolina_Lawns.pdf) gives specific recommendations.

When it comes to pruning, there are at least two issues that can result from improper timing: loss of flowering for a season and winter damage due to late growth. Generally, plants that flower in the late winter or early spring form their flower buds during the previous year. So, if you prune them while they’re dormant (a recommended time to prune many plants) you’ll be cutting off flower buds.

Depending on how severely the plant is pruned and what type of plant it is, some flowers may still bloom on what remains of the plant, but the general rule of thumb is to prune such plants after flowering, unless you’re pruning them very severely (e.g., renewal pruning, in which a shrub is pruned to within a few feet of the ground). In that case, pruning during dormancy is recommended, as it is for most plants that flower during the summer or fall. Pruning late in the summer is a no-no in most situations.

The best timing(s) for herbicides, insecticides, fungicides and other pesticides will depend on the lifecycle of the weed, insect, fungus, etc., that one is trying to kill. For example, if you find that you have annual weeds like crabgrass and henbit (to name just two of many) and plan to spray them, it makes more sense to do this before they develop seeds than after. Once annual weeds (ones that live only for one year) have produced and released mature seeds, they’ve done their damage by spreading seeds for future years and will die soon anyway, on their own.

If a person is going to spray for corn earworms, they need to start early (when the corn silks appear), before the larvae of the earworm get into the ear. Corn earworms also illustrate another “timing” phenomenon: Corn planted early in the season is less likely to have severe corn earworm problems than corn which is planted late.

My example relates to fire blight, a common disease on apples and pears caused by bacteria. Once a person sees new occurrences of the characteristic, burnt-looking “shepherd’s crook” at the ends of branches, the time to start spraying has passed. When the disease has been a problem, a person can spray streptomycin, starting when blossoms open, since blooms are a major point of infection.



Mary Helen Ferguson is a horticulture agent with the Randolph County Center of the N.C. Cooperative Extension Service in Asheboro. She can be reached at (336) 318-6000 or by e-mail at maryhelen_ferguson@ncsu.edu