Winterizing Warm Season Grasses is a No No

Question: The lawn care company recently applied an application of “winterizer” fertilizer to my Bermuda grass. Do you recommend winterizer fertilizer on warm season grasses?

Answer: If this is a well established lawn it is doubtful you need a fall application of fertilizer unless a soil test indicated a low level of potassium. Unfortunately, there are many products on the market sold as winterizer fertilizer. Cool season grasses such as fescue do most of their growing in the fall and spring and they need nitrogen to grow. However, many of these products are also used on warm season grass. Fall nitrogen application can be damaging to warm season grasses. Instead of increasing the cold hardiness, the opposite effect results. A warm fall will lead to continued vegetative growth which sets the plants up for cold damage. Check with your lawn care company and ask for the analysis of the fertilizer used. If the first number is 5% or below, it probably won’t hurt but it would be better if no nitrogen is applied to Bermuda and other warm season grasses after August.

I would suggest you have your soil tested to see if you need potassium or not. If you fertilize during the summer months it is very doubtful extra potassium in the fall will provide any benefit. However, if you do apply fall fertilizer, always apply it onto dry foliage to reduce the likelihood of salt burn.

A soil test provides a wealth of information and can be done for only $7 in Alabama and many state Extension offices offer similar services. Fall is a great time to test the soil because the lab is not as busy and if you need lime you have time to get it out on the lawn before spring growth starts. The lime will slowly move into the soil with winter rains and the pH will gradually rise in time for the first spring growth spurt. Once you receive your test results you may want to contact your local Extension office to talk with a horticulturist about your test results.
I have seen many test results that indicated an excessively high level of phosphorus and potassium. Phosphorus does not leach from the soil very quickly and it can build up to the point that no phosphorus will be needed for many years. Potassium can become so high that it interferes with the uptake of other elements such as magnesium and can result in a lighter green turf color. Also, be aware that an excessively high rate of potassium fertilizer can cause foliar burn.

Fall Is For Planting

Question: I am planning on planting some trees and shrubs this fall and would appreciate some planting tips to insure success.

Answer: Most of the time I get questions after newly planted trees and shrubs start to die, but I much prefer offering pre-planting advice to avoid problems.

Fall is the best time to plant most perennial plants including trees and shrubs and even most herbaceous perennials. The keys to success start even before planting perennials in the ground. It is always advisable to do a little research on the front end. There are some important questions you should answer before planting anything. One, are the plants I have in mind adapted to our climate? And I don’t mean adapted just to cold, but also to heat which is often as important as cold in our area. Two, will the plants tolerate the drainage within my soil? Poor drainage causes more plant death in heavy clay soils than drought does. Third, is the site chosen adequate for continued growth of the chosen plants? You should always think about the mature size when choosing the planting location and plant material.

The actual planting process will determine in large part the future growth and possibly whether or not a plant survives at all. There are at least two myths about planting woody plants that reduce your chance of success.

The first myth is that you should amend the planting hole with loose organic matter. If you have a lot of clay in your soil you should not use any organic soil amendments. There are several potential problems with adding organic matter and they all revolve around water. If organic matter is added to a hole surrounded by heavy clay soil, the water movement is drastically altered. You will have one of two problems. Either the water will not move out of the hole after rainfall, causing a bathtub effect, or the organic matter will dry and not re-wet well. Both of these scenarios will lead to root death. Plant wilting is not a good indicator of whether the soil is too wet or too dry because drought and excessive water both cause wilt.

The second myth is that you should not disturb the root ball coming out of the container. This myth relates to the previous myth, but needs some further explanation. Most plants are grown in containers at the nursery in a very light ground pine bark mix. This mix is great for growing shrubs and trees in the nursery but can present terrible problems in the landscape. If this loose bark is allowed to remain intact, the water movement issues described above still apply, with the added problem of air pocket development around the roots as the bark decomposes. Therefore, it is best to gently wash most of the loose bark material off the plant until it is, for all practical purposes, a bare root plant. This may involve pulling the roots out if they have started winding around the root ball. If necessary you can prune or slice these roots to help make this job easier, but try to leave as many roots intact as possible.

The planting hole should be shallow and wide. The depth only needs to be as deep as the root ball, but the hole should be two to three times the width of the longest lateral roots. Look for the uppermost lateral root to determine the planting depth. This lateral root should be at grade or slightly above the surrounding soil grade. Make a small ring of raised soil to hold water near where the outermost roots extend. Keep this area moist at all times for the first several weeks and then gradually decrease watering frequency and increase watering depth to encourage deeper rooting. Mulching the root area can give you a false sense of security about whether the plant has adequate water. It is very important to check the root area frequently to avoid drying. Do not apply mulch more than a couple inches thick.

A couple other post plant care tips are to keep the area around trees and shrubs weed and grass free, widening the weed free area as the plant grows. Also, avoid using weed whackers or mowers near the plant base.