Fall prep: what Lowcountry lawns need now

I hope everyone had a great labor day and had some time to enjoy their outdoor space, while we caught a break in rainfall. Following the rainfall from last month, we have also had a slight break in summer temperatures as well, but we expect continued fluctuation as we work our way into Fall.

It is important to be keeping an eye on temperature and rainfall as we progress through September so we can adjust watering accordingly. Lawn fungus will begin to become increasingly prevalent from over saturation, especially as we begin to cool down.

We are reaching the point of last call for lawn fertilizer, especially nitrogen. Nitrogen provides growth and color to our lawns. It is important to avoid putting out any nitrogen fertilizer within 6 weeks of our first frost.

Late summer fertilizations can be beneficial by providing a last push of growth and strengthening your root system for winter, but it is ideal to get it down sooner rather than later. You may also want to consider going with a blend that is higher in potassium and lower in nitrogen. Most bags of fertilizer have 3 numbers on them (Ex. 15-0-15) the first number represents the percentage of nitrogen, followed by phosphorus, then potassium.

After an abundance of rain we have seen an increase in weeds. There are thousands of weed controls available on the market, but they can be separated into two broad categories: pre-emergents and post-emergents. Pre-emergents have specific time frames in which they can be applied and are used to suppress weed from coming through. Post-emergents can be applied throughout the year to control existing weeds that they are labeled for.

For summer pre-emergents to be effective, they have to go down in the late winter/ early spring, prior to soil temperatures getting high enough for seed germination. This timeframe requirement can make controlling weeds in the latter part of the summer more difficult as the effect of the pre-emergents lessens over time, especially with lots of rainfall.

For this reason post-emergents become more popular this time of year, as they can help suppress and control already germinated weeds. It is important to review the label on post-emergents to find the specified rate, ensure they are safe for your grass type, and make sure they are listed to control the weeds you are targeting.

In the same way that spring pre-emergents are used to suppress summer weeds, Fall pre emergents are used to create a barrier against winter weeds such as poa annua. September is a great time to apply fall pre-emergents. You can either apply a full rate at this time or a half rate now and again in November for better longevity. Although no pre-emergent will stop all weeds from coming through, they will significantly reduce the amount that do appear and keep them from taking over your grass as we enter dormancy.

In regard to your trees and shrubs, as the temperatures begin to cool down, and the heat of summer is gone, it is important to prune out any unhealthy/ diseased foliage before we get into the winter months. Remember not to do any major pruning too close to a freeze (no pruning 30 days before/30 days after the last freeze).

We have seen quite a bit of fungal activity on plantings this time of year, likely due to humidity/rainfall. Be on the lookout for leaf spot, discoloration of the leaf, and even full branches dying back. Make sure we are not over watering our plantings as we cool down to avoid root rot and other types of fungus. Established plants shouldn’t need very much water in addition to the rainfall.

We are still dealing with a few insect problems like caterpillars, scale, and whiteflies, but insect activity will begin to decrease the more it cools down. Potassium is very beneficial in Fall for ornamentals to keep the roots strong and help them get through the winter, especially if you have any plants already struggling.

Zach Deloach is the owner of Lawn Doctor of Beaufort County.