Ornamental cold protection reminders
It is obvious that cold damage to ornamental plants can be a problem during the winter months. In a previous column, we discussed cold acclimation. In fact, I have been sharing information on cold protection of plants in various venues and outlets in 2019.
I will not go into major detail on cold acclimation, but just keep in mind that this is a process that happens in late summer and early fall where the plants will prepare themselves for winter. The process is started by cooler temperatures and shorter day lengths. It could be possible that plants this year did not acclimate properly due to the hotter temperatures this fall and then a quick jump to colder weather.
My goal today is to give important reminders on how to cold protect your ornamental plants this time of year. I will be sharing information from a UGA publication by Bob Westerfield, UGA Extension horticulturist, and Orville Lindstrom, professor of Horticulture.
Back several years ago we experienced several rounds of cold and snowy weather. The following spring, I conducted many site visits and assisted numerous clients by phone on cold damage issues in the landscape. Not all, but many of the issues were caused by pruning at the wrong time of year. You need to stay away from late summer or early fall pruning in general. When you prune, you stimulate new growth on the plants. This new growth is susceptible to cold damage. I would add it is important to know the proper pruning time for each of the ornamental plants in your landscape.
I remember as a young county agriculture agent in Bartow County keeping a chart of proper pruning times for the more popular items above my computer. That list can still be used today. In fact, I can email that list to any landscape enthusiast that wants to know the correct pruning times. Proper transplanting time can also be a key in cold protecting your plants. Ideally, you will transplant in the early fall. If you wait to late fall or early winter to transplant, you can be setting the plants up for cold injury. These plants may not be acclimated correctly when low temperatures arrive.
I would like to drop back and go over proper plant and site selection. If you are starting a new landscape or wishing to add some ornamentals, proper plant selection is important. Choose plants that meet the minimum cold hardy requirements for your area. On the flip side, make sure the plants can handle the summer heat of Northwest
Georgia too. Another tip is to evaluate your property to determine the warmest and coldest spots in your landscape.
In general, the coldest areas will be on the north or northwest parts of the property. The warmer spots should be on the southern side of the area. I will add that determining the microclimates on the property can be important too. This involves looking at elevation, land form, soil properties, canopy cover and proximity of structures or other plants per Westerfield and Lindstrom. For example, you could plant a cold sensitive plant near the part of the home that receives southern exposure.
What can you do for container plants for cold protection? I remember as a young agent going to a home where the owners had a tremendous number of large cactus plants. They would move the plants indoors for the winter.
First, it was a tough job due to the size and number of plants. I think the husband had made platforms with wheels so the large plants could be rolled into the garage. Placing container plants in a home, garage, greenhouse or shed is an option. The main problem with container plants are the roots are exposed above ground. Cold damage to the roots should be avoided. Another option for container plants is to place a protective covering over them.
If you have to leave container plants outside, you can push the container together and mulch or cover them to reduce heat loss from the sides of the containers. You can wrap the bases of the containers in either plastic, burlap or blankets to reduce heat loss.
You can cover the actual plants with sheets, blankets or even cardboard boxes for cold protection.
Stay away from covering plants with plastic. Plastic can cause temperatures to rise quickly, thus damage. You need to remove any covering during the day to allow for ventilation and release of heat that is trapped by solar radiation.
Do not forget water needs before a freeze event. Keep in mind that moist soils will absorb more heat thus helping to keep a higher temperature around the plants. You should check plants and water if needed prior to a cold event. Also, mulching around the base of the plants will help conserve moisture and reduce heat loss.