First Freeze – By Mark Govan, Host “Florida Gardening”

The first big freeze of the season has past and many of our lawns and ornamental plants are showing signs of its cool breath. Bahia and St. Augustine lawns have browned out and the weeds which were green have withered and died. Even those nasty carpet grass weeds in our lawns have browned out beckoning us to remove them. Tender ornamental plants have lost some of their foliage and others look as if they may be dead. If you are seeing these problems in your yard and you want to know what you can do to protect your lawns and plants from any further damage, then this article is for you.  Finally, I will give you my personal rating on several products which you can purchase to protect your favorite plants.

            The damage from the cold weather intensified the second night of the freeze when the winds died down and a heavy frost set in. Frost seems to do more damage than just cold weather to many of our plants especially our turf grass. This damage could have been minimized had the homeowner merely watered the lawn the night before the freeze. Watering the lawn locks in the warmth of the day and helps to reduce heat loss at night protecting your lawns root system. If you did not water your lawn and the temperatures were low enough in your area then you are probably noticing that your lawn looks brown and stressed. Look closely at your entire lawn. You may notice some areas of your lawn like those areas under trees or around the driveway or sidewalk which may still be green. These areas were kept warmer by the tree line and the cement. However, in the middle of the lawn you may notice the grass is all browned out. This is where I want you to play close attention.

            If your lawn in this area is all the same color of brown then you are ok, but if you see patches of grass which look almost whitish in color, then this can be due to a weed grass called Digitaria. Digitarias or Carpet Grasses are the first areas in your lawn to turn a whitish-brown and they stand out when you are looking over the entire lawn. These whitish-brown areas are the indicators for homeowners of how much of this weed grass has infested their Bahia or St. Augustine lawns. These areas should be cut out and replaced with new sod.

            New sod is still available from local garden centers and even though the cold weather may not be over, new sod placed over the cut out area will be protected from the freeze by ground temperatures which never freeze. If you do not remove this grassy weed now, these areas will again turn green with warmer temperatures and continue to spread during the summer. I need to stress the point of removing this grass now because there is no control to kill this grass during the summer other than Round-up which kills the good grass and the bad grass. If you wait, you will only get minimum control. Many of these patches of weed grasses will grow and double their size each year.

            As for the other broadleaf weeds which may have died with the cold weather, they will be back and so will your turf grass. Normally, only the blades of grass are severely burned during our cold spells. This gives the roots protection from the cold and allows the grass to re-grow once temperatures warm back up. If you live in our Northern Counties there is one variety of turf grass which is more cold tolerant than others, this variety is called Raleigh, St. Augustine. Although it may be a good idea to have a cold tolerant variety of turf grass, there are several things you can do to improve the cold resistance of your lawn.

            The first thing you should do is to winterize your lawn. Winterizing your lawn means that you fed your lawn the elements needed in the Fall to protect the root system through the Winter months. This can be accomplished by fertilizing your lawn with a good quality 8-0-14 fertilizer in September or October. The number fourteen represents the potassium in the bag of fertilizer and this element is responsible for root growth, disease protection, and cold protection. Lawns which have plenty of available potassium can withstand more cold weather and diseases than lawns without this element can. Potassium will also help your lawn to green up quicker in the spring than other lawns without potassium.    

            Ornamental plants including tropicals do not like cold weather and need protection when temperatures fall below 45 degrees. Because many of our tropical’s can be severely injured or killed by these temperatures, we must protect these plants before the freeze. Some people put out blankets to cover the plants while others use lights under their plants to keep them from freezing. If you have containerized plants you can bring them into the garage or home. Orchids should be brought inside if temperatures are going to be below 35 degrees for an extended period of time.  

            Those plants that were left outside unprotected and are showing damage need to be left alone. Do not prune the dead leaves off the plant as these can insulate the plant from additional freezes. Do not fertilize the plant to encourage new growth as this new growth can freeze quickly if temperatures drop again. If another freeze is called for use some of the methods I discuss below to protect your plants.

            Adding mulch like “Sweet Peet” over your plants root systems will help your plants in two ways. Mulch helps to insulate the root system by providing a barrier against the cold. Even if the plants leaves are affected by the cold, the root system will be protected and allow the plants to recover much faster once temperatures rise. Be sure to add at least 3 inches of mulch for best results. Do not place this mulch directly around the trunk of the plant. Stay at least 3 inches away from the trunk to prevent fungal pathogens from entering the plant. Rubberized mulch or stones placed around plants are not recommended and do not protect your plants from the cold.    

            There are several products on the market you can use to help your plants during cold temperatures. Freeze Pruf, Frost blankets, and Foam are just a few. Freeze Pruf is a liquid which can be sprayed directly on your plants and improves the plants natural cold tolerance by up to 9 degrees. Freeze Pruf needs to be re-applied every month during cold weather. Because of the time and money spent using this product this is my third choice. Frost blankets are available at most retail garden centers. Make sure if you are going to cover your plant with one of these that you cover the entire plant to the ground. The addition of a light bulb or other heat source can help maintain non-freezing temperatures under the blanket especially during windy nights. Use soil along the base of the blanket to ensure a tight seal. Frost blankets if properly applied with good ground contact can last for several weeks and are easy to use. This is my number one choice. Never use plastic blankets around your plants as this actually intensifies the cold and when left on the plant during the day may burn the plant.   

            Jack Frost Foam or Botanical insulation foam is generally used by professional growers to protect their crops from freezing weather. Most of these foams are used only for short durations. Foam applications disappear after about 8-14 hours and then need to be re-applied. Foam is a great way to save annuals or perennials which are small or low to the ground. Foam will also save plants from freezing weather better than other products which merely protect the plants from cold not freezing temperatures. If you own a nursery or specialize in high-dollar plants then this is your product.

            I hope you will look out for the weed grasses in your lawn and remove them now. Protect your plants using the methods or products I have suggested here. Let us all hope we do not have any major freezes this year and remember, without plants we would not be here!

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