Freeze Damage

January 3, 2011 by  
Filed under Blog, Garden Center, V.I.G

What to do before the freeze:

Take a walk around your yard and assess what plants may be in danger of cold temperatures.

WHERE you plant tender plants is as important as what you plant. Planting tender plants in higher areas versus low areas where cold settles or water accumulates are important considerations. Planting in areas that are protected by an overhead tree canopy will increase their chances of surviving a cold snap by trapping the earth’s radiant heat and keeping frost from landing in the plants below. Planting with protection from windbreaks will minimize damage from drying winds, and mulching will protect plant roots and minimize cold damage and water loss.

WHAT you plant is as important as where you plant. Hardy evergreens and deciduous trees will make it through the cold with minimal damage. Perennials will return in the spring after dying back in winter. Even tropicals that die back to the ground may return. After the cold snap last winter, many homeowners found that if they were patient, even their most tender plants emerged triumphant once the soil warmed up.

Below are a list of some common plants that are cold sensitive and should be covered:

- Roebelenii Palms – Blue Daze
- Queen Palms – Bird of Paradise
- Hibiscus – Crinum Lily
- Crotons – Varigated Ginger
- Hawaiian Ti – Philodendron ‘Xanadu’
- Gold Mound Duranta – Oyster Plant

How to protect your plants:

HOW to protect your plants is always a concern. VerdeGo reccommends using frost cloth to cover your plant material and it is sold at our garden center. Frost cloth traps heat from the earth and breathes allowing air circulation. The cloth will sheet some moisture that can accumulate from frost which will minimize leaf damage that can happen when blankets and sheets get wet from frost and then freeze. Try to stay away from plastic and remove all covers as soon as the sun comes up in the morning. Protect container plantings by grouping together where possible near building walls and cover to ground level to trap radiant heat. Separate plants in the morning when uncovering to improve air circulation.

WHEN covering Roebelenii Palms (Pygmy Date Palms), take a piece of string and tie up the fronds together similar to a ponytail. Then take your frost cloth and wrap the fronds down to the trunk. The heart of the palm is where the fronds meet the trunk and this is the main area to protect.

Ornamental plants can be protected during a freeze by sprinkling the plants with water. Sprinkling for cold protection helps keep leaf surface temperatures near 32°F (0°C) because sprinkling utilizes latent heat released when water changes from a liquid to a solid state. Sprinkling must begin as freezing temperatures are reached and continue until thawing is completed. Water must be evenly distributed and supplied in ample quantity to maintain a film of liquid water on the foliage surfaces. Irrigation for several days may water soak the soil resulting in damaged root systems and/or plant breakage due to ice build up. Consult Extension Circular 348, Sprinkler Irrigation for Cold Protection, for more technical information on this subject.

What do after the freeze:

We have had many calls over the past few days on what to do with freeze damaged plants. The answer is NOTHING.

Plants become damaged when ice crystals form in the plant cells, the crystals expand, and cell walls rupture preventing the plant from maintaining shape resulting in collapse and drooping. If severe, this can kill tender tropical plants. On hardier plants the damage will appear wilted and the leaves will curl down. The damaged stems and leaves will darken and turn black (the more succulent the plant is, the faster the smelly soft rot will develop). All dead tissue will support populations of bacteria and various fungi as a natural part of the decay process. It may be beneficial to remove rotting, soft and decaying leaves to prevent the spread of possible fungal diseases.

Pruning and trimming should be postponed until cold temperatures are no longer expected. Anything left on top (whether dead or alive) will help protect the plant should we get another cold snap. During the last week in February and first week of March, if no cold weather is forecast, you can begin pruning. Start at the top of the plant and work your way down until you find green in the wood. If you find no green, trim to 6” above the ground. Fertilize with a slow release granular and water in.

Palms: It is the heart bud that is vital to palms. If you see any green around the heart (where new fronds emerge) chances are good that your palm survived. Dwarf Pygmy Date Palms, Foxtail Palms, and Christmas Palms are showing the most damage. Fronds should not be removed if they are green (even if they are spotted from frost and cold). The more green leaves the better to assure adequate photosynthesis during recovery.
Note that just because the heart is brown does not always mean your palm is dead. New fronds may emerge during spring growth. Your palm may show signs of distorted leaves when new growth does occur, this is damage that occurred during the freeze, and the palm will eventually grow out of this with the second or third emergence of new fronds.
Fertilize with Nurserymen’s Sure Gro 8-4-12 slow release palm fertilizer March, July and September.

For more information contact our Garden Center

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