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Growin’ Green

How To Apply Herbicides To Dormant Lawns

By Brent Gray

Each winter I get calls requesting information on applying nonselective herbicides to dormant lawns.  Glyphosate (Roundup) herbicide applied at the labeled rate of up to 16 ounces per acre to dormant bermudagrass can be an effective method of controlling many winter broadleaf and grassy weeds. The efficacy of the herbicide is much greater when temperatures rise above 60 degrees so it becomes a challenge to the applicator to target the application when the turf is dormant but yet have temperatures warm enough for the herbicide to be most effective.
The greatest challenge and fear of applying glyphosate or other non-selective herbicides to dormant turf here in Mississippi is determining if the turf is truly dormant or not.  With the winter fluctuating temperatures we often experience our turf may never go completely dormant.  The extended period of sub-freezing temperatures of this past week probably has put warm-season turf species lawns in as dormant condition as they will be this winter.  Research data indicates that common bermudagrass is slightly more tolerant to glyphosate than hybrid “Tifway” bermudagrass and at the labeled rates of 16 ounce per acre or less will not kill semi-dormant bermudagrass but may delay spring greenup.
Therefore, my suggestions to anyone planning to apply glyphosate or other non-selective herbicides to their lawn is to 1st) carefully examine the turf for stage of dormancy; 2nd) read the label completely to be certain the herbicide can be applied to the turf species you have  and do not exceed the label use rates; 3rd)  accept the possibility of delay in spring greenup; and 4th) assess other weed control options as well.
Reports of asparagus sprouting are already starting to come in. Any bed older than five years is giving its owners an early treat. Emerged spears from crowns  less than three years old should be allowed to develop. Three or four year old beds  should have partial harvest.
Good Friday Gardeners take note: there are about nine weeks until the day to plant. If you are planning to order seed from a distant source and grow your own transplants time is running short.  Seed can take three weeks to arrive and tomato transplants  generally take six weeks to reach desirable size so now is the time to order.  
The recent rains and slow drying conditions have made gardeners aware of the shortcomings of their clay soil. The temptations to add something to make the soil better gets stronger when the sun is shining but water is still filling our footprints. Just be aware that you need to add one third to one half the volume of soil amendment to each volume of soil to achieve the desired  modified soil. This means adding four to six inches of sand, calcined clay, expanded slate, expanded clay mineral or other large particle soil amendment and thoroughly mixing it with a foot of the natural soil. Most gardeners just make an artificial soil of half sand and half organic matter and grow in raised beds on top of the clay soil.
Onion transplants are in at many garden centers. The earlier you plant them the bigger the bulb you will get. Onions are relatively easy to grow as long as you pay attention to them. They have few insect pests and can be grown without many fungicide applications in most years. The problem with onions is their limited root growth means they are not very drought tolerant nor are they very good at extracting nutrients from the soil. As long as you keep the soil moist and the nutrition level high they will grow well. There are many sweet onion varieties available, many of them have “Georgia” in their name. The long time favorite for Mississippi gardens is  Texas Super Sweet or 1015y. Any onion that says grano or granex will also produce a sweet onion. If you prefer a more pungent onion, get one that is described as “Spanish”.

Now is the time to prune roses,  fruit trees and vines. Now is not the time to prune evergreen shrubs. Pruning evergreens now may induce early growth which is likely to be killed by cold. Wait until you see signs that new growth is about to begin before pruning needle evergreens and non-flowering broadleaf evergreens. Wait until after flowering for spring blooming ones.

Horticulture Tips Wayne Wells, David Nagel

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