Xtremehorticulture

Assess Plant Cold Damage in the Spring and Fix It

Q. Are there are any plants I need to prune or trim down before the frost comes to the Las Vegas valley this year?  I noticed that oleander suffers greatly from frost, foxglove, asparagus ferns, potato vine and a purple flower trumpet flowered plant are kissed when the frost comes. Should these be covered also? A. Damage from frost will be variable in different places throughout the Valley. There are places which are naturally cold spots and others in windy locations. These areas will be hit the hardest.             Then we have the variability of the weather. It was not too long ago that we had unusually Difference in cold damage between two different types of Oleander warm winters where it hardly froze at all. Then we had a terribly brutal winter with the coldest temperatures hitting us in February when plants were just waking up from dormancy.             Then we have variability in the plants themselves. As far as oleanders go, there are winter tender types and there are very cold tolerant types.             My basic advice is to leave most ornamental plants alone. Wait until the coldest part of the winter has passed, or you begin to see the beginnings of new growth, and then remove what has been damaged. Oleander and asparagus fern can be pruned to within a few inches of the ground and they will recover. Oleander will recover by summer if it is pruned to within a few inches of the ground. in late winter             This doesn’t hold true with citrus. Citrus planted in cold locations will have to be protected if you want it to survive or you want fruit.

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You Will Not Protect Bougainville from Freezing by Feeding Them

Q. Before the first freeze here in Las Vegas, probably in 3-1/2 weeks, what may I feed them?  Might there be something simple, without figuring amounts and all kinds of mixing? I have three plants, all in the ground.  They are six years old this year, and I wrap their bases before the freeze. They always come back come March/April, and bloom beautifully in August/September through October – when the real heat hits. A. I like your idea of wrapping the bases of the plants before any freeze. Unless you have a very warm microclimate in your yard, and there are some of those in Las Vegas, you will see damage to them at the first light freeze with temperatures below 32° F. The harder the freeze and the longer it lasts, the more severe the damage. Bougainvillea after freezing weather in Las Vegas Wood mulches will also protect the base of bougainvillea but wrapping it is more effective. This way when it freezes it will kill the top of the bougainvillea to the top of the mulch or wrap and not any further. Of course this works to temperatures below freezing for short periods of time. If the temperatures are extremely cold, or if these temperatures last a long time, then it will freeze the plant to the ground. How well you protect the base of the plant will determine how strong it will come back, or not, next spring. Having bougainvillea in a spot in the yard which does not have a lot of wind and is very close to a warm, South or even better yet, West-facing wall will improve its chances for survival. Freeze damage hits the youngest and thinnest plant parts first during a light freeze and the part of the plant most exposed to wind and less protected by warm south or west facing walls Plants that freeze to the ground will come back like gangbusters next spring because of their established root system. Plants that are first planted have to grow both the roots and the tops and so growth is divided between the two. Plants that have an established root system and freeze to the ground only have to grow the top back. So all of the spring growth is funneled to top growth so we see huge amounts of top growth in the spring. Spring recover of oleander from a winter freeze You do not want to feed them anything this time of year. Just make sure they get watered. This goes for any winter tender plant. These plants should get no fertilizer applied to them that promotes growth any time after mid-August. Fertilizers which stimulate new growth will cause the plant to become more succulent and lower its chances of surviving winter freezes. This is not true of plants that have no problem surviving winter freezes. In fact, those plants can receive mid fall applications of fertilizer with no problems. A mid fall application of fertilizer can substitute for a Spring application but not winter tender plants.

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