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Plant Recovery After a Hard Freeze

Arkansas, and many other states around us, have just experienced unusually low temperatures, for an extended length of time, along with high snowfall amounts.  Before, during and after events such as this, we get many calls about what to do and how to care for plants that may receive damage due to weather.

Preparation for a Hard Freeze

Let’s go back to the ‘before’ for a minute. Here is a link to our Freeze Warning post with extensive preparation tips. While we know this information isn’t actionable at the moment, we want to share it as much as we can so everyone can be as prepared as possible moving forward.

Keeping your plants healthy and happy year round also helps reduce winter damage.  Keep in mind that newly planted shrubs and trees might experience more freeze damage than older, healthy plants with a more established root system.

 

During a Hard Freeze

If you cover plants, remember to keep an eye on them during warm days, so as not to overheat them with the covering. You may have to remove the covering for a period of time and the recover if another freeze is about to happen. Support blankets or take them off during snowfall to avoid plant breakage.

During a heavy snow event, plant branches may get weighed down and begin to bend or even break.  When it is safe, try to knock snow off bending branches.  Evergreens tend to experience this more; snow usually safely goes through bare branches just fine.

Ice is a different story, and unfortunately, can be much more difficult to trouble shoot. Avoid trying to remove ice from plant branches.  They are brittle when ice covered and more likely to break.

 

February 2021 Winter Storm

While we had very low temperatures forecast for this winter weather event, they turned out to be lower than expected for a longer length of time, potentially causing more plant damage than expected. You may have noticed zones being mentioned on plant tags. Each plant has a zone that it should be hardy in; Little Rock is Zone 8a, which has an Average Annual Extreme Minimum Temperature of 10-15°F. The weather we recently experienced reached into the 6b Zone, with one night being recorded as -1°F. Here is a link to a Plant Hardiness Zone map for reference.  Plants that are hardy only up to Zone 8a may show damage from these extreme temperatures.

We also had heavy snowfall during some of these extremely low temperatures, making it more difficult to adequately protect plants with frost blankets, due to potential snow weight on blanketed plants.  In some ways, this snow was helpful; it has insulated the plant roots. However, the exposed top growth of the plant will likely show damage.

 

Recovery After a Hard Freeze

Wait until after the ice and snow have melted to assess for damage.

The signs of of freeze damage are evident on many plants but do not always look the same.  On tropical and sub topicals they may appear droopy or shriveled, like they are in need of water. Additionally they may turn for green to brown or purple, and stem splitting may happen. If this happens plant recovery is unlikely, or it may take several growing seasons to recover. In extended freezing temperatures, ice will form in the plant cell and the cells rupture causing damage to the plant tissue. This kind of damage is irreversible with most tropicals.

If you get caught off guard, or we have record breaking lows, and your plant suffer from a freeze, BE PATIENT, don’t go for the pruner and start cutting everything back. It may take several days or weeks to show how much damage has been done to your plant. If the plants become mushy and soft this should be removed to avoid get secondary fungal growth. Broken branches can be removed.

With many woody plants, we suggest waiting until spring when the new growth appears before pruning out damaged plant branches. You can check for life in woody plants by scratching the bark on the stems to see if it is green underneath, if you find green that branch is still viable and your plant is still alive.

As for right now, we expect to see some partial defoliation, or at least leaf discoloration, of broadleaf evergreens. Again, don’t start pruning now; wait until new spring growth emerges and cut out branches that don’t leaf back out.  Ideally, plants will shed damaged leaves and new ones will emerge this spring.  Landscapes might start looking pretty bad before they recover.  We already know this will be concerning and you will want to do something.  Truly, the best thing you can do is have patience.  If they haven’t leafed out in April, do a scratch test and go from there.

March 2021 Update: We suggest doing a scratch test now and looking your severely damaged plants over for leaf buds that might be swelling with new leaf buds.  Broadleaf evergreens that show no green under the outer bark, have dry, brittle branches and no signs of life may not recover.  Don’t wait too long to replace them; we expect shrub shortages due to grower damage this winter and above average demand last year.

A Few More Tips

Cool season annuals such as pansies look a bit worse for the wear right now. They should be fine (we hope) if they were healthy and hydrated going into this cold weather. The insulation of snow most likely helped them.  During our next warm spell, when temperatures are above 50 degrees for a few days, feed them with liquid fertilizer, such as Br-61 or Miracle Gro.  Wait until the soil has dried out from all the snow melt or the plants won’t take up the fertilizer. You can also apply slow release Ferti-Lome Premium Bedding Plant Food if you haven’t given them any since planting.  While it’s not necessary, deadheading (removing spent blooms) will encourage new blooms, give them a cleaner look overall and in general, help them recover faster.

March 2021 update: It’s time to fertilize those pansies!

With perennials, it’s a wait and see game.  Tender perennials may struggle to come back or not come back at all but winter hardy perennials should fair better. Wait to trim woody perennials; examples of these include Russian sage and butterfly bush. You might find that they leaf out lower on the plant than usual. After they flush out this spring, cut dead growth off above where the new growth is emerging. For evergreen ferns, like the Autumn ferns shown below, remove all winter damaged fronds before new ones emerge.

For groundcovers like liriope, trim back as usual after this cold snap ends. Same with shrub roses.  Getting rid of damaged growth could help them flush more strongly this spring. For tips on what to prune and when, visit this post.

Plants like lantana, Mexican petunia, and purple fountain grass are not perennial here, even though many people have them come back year after year.  There is a good chance these plants won’t come back this year.

Protect your lawn by staying off it as much as possible until it dries out.  Putting weight on saturated lawns can damage the root system and cause ruts. St. Augustine and Centipede turf grasses might have some winter damage and fail to break out of dormancy this spring.  There are no actions you need to take now, just prepare yourself for that possibility. Let’s all hope that the snow provided sufficient insulation for these less winter hardy turf grasses.

Speaking of lawns, all of this extra water could decrease the effectiveness of pre-emergents (weed preventing herbicide).  If you haven’t applied yours yet, wait until this snow is gone and the soil is less saturated.  If you have already put yours down, consider another application sooner than later.

March 2021 Update: It’s time to re-apply pre-emerge if you haven’t already this spring!

 

Long Term Recovery

Plants that seem fine for the next few months may suddenly show signs of root damage this summer.  This would happen if the root system or a large portion of the root system was damaged or killed due to these unusually low temperatures.  The plant may not show the damage until the heat stress of summer arrives.

To give your plants a boost this spring (April), feed with a balanced, slow release fertilizer such as Good Earth brand Jump Start or Ferti-Lome Start-N-Gro. Make sure the plant gets adequate water but avoid over watering.

Caring for your plants is a labor of love and it may take some additional time to protect them and help them recover from a hard freeze.  If you have any questions, please reach out to us.