Dealing with weather-damaged plants

Even plants that survive and thrive season after season in Colorado are still subject the ravages of Mother Nature. Hail, wind and severe winter freezes challenge our plants’ survival and leave damaged or dead plants in their wake.

Along the Front Range, an early, harsh freeze in November 2014 created a severe weather event that damaged or killed many plants that traditionally overwinter. During the growing season, hail has pummeled the survivors. How do you know what is dead or alive – and what is worth nursing back to health?

Hail damaged annual flowers and edibles
Plants that are completed stripped of foliage and have broken stems should be replaced. If less than one-third of the plant remains, it is probably not worth trying to save. Other plants with less damage might be salvaged, but they will need time and care to recover.

  • Trim and remove severely damaged leaves so that the energy of the plant is directed to create new growth. After trimming, spray edibles with a copper-based product available at garden centers. 
  • Apply fertilizer to promote growth.
  • Water regularly without stressing plants with too much or too little water.
  • Place new plants between damaged ones to provide instant color in the case of annuals – and to help insure a harvest in the case of edibles.

Living with hail: In areas more prone to hail, use a cloth designed to protect plants from hail.  It allows moisture and light to reach plants while protecting them from hail. When selecting flowers, look for finer-leafed plants such as cosmos which the hail often falls through rather than shreds.

Perennials often have secondary buds that will provide new growth following hail damage. Perennials also require optimal care following hail so that they not only survive the current season but gain the health to overwinter and bloom again next season. 

  • Trim perennials back as far as the extent of the damage is visible. This also applies to perennial grasses.
  • Apply fertilizer to provide nutrients that will generate growth.
  • Water adequately. Xeric plants may need more water than usual to help them recover more quickly.

Shrubs and trees
In late June or July, it should be possible to assess the winter kill of harsh weather events such as the severe freeze of November 2014. Because spring buds are set the previous fall, freeze damage will result in fewer or no flowers or fruit on flowering trees and shrubs. 

Browned leaves will not turn green. To assess the extent of damage, move up the plant and past the leaves to check how far back dead material extends. Dead twigs will snap. Moving further back on the branch, you can use a knife to scrape the top of the branch to look for live wood.  Prune twigs and branches at the point where there is live, green wood. Dead branches in shrubs and trees should be removed following freeze damage or any storm damage. 

Also check trees for frost cracks in the trunks. While there is no intervention you can do, monitor the tree. Often, with good cultural practices the tree will recover. 

Plants stressed by freeze, winds and hail need consistent cultural practices to help them regain their health.

  • Following serious winter kill or storm damage, avoid applying fertilizers that promote fast growth. Instead, use a slow-release formulation low in nitrogen.
  • Because stressed plants are more susceptible to insects and diseases, monitor trees and shrubs for signs of insect or disease problems and be ready to treat the plants when the situation warrants it. Call on a pro to evaluate causes and recommend treatments, as needed.
  • Make sure trees receive adequate water during the dry months of winter. Providing water during the dry periods in winter protects trees from drought stress which may not show up until the next growing season.

Ongoing periods of rain
Rainy periods as occurred in May-June 2015 will saturate soils. Saturated soils will also cause evergreens to uproot and fall over during high winds. Colorado Blue Spruce are among the trees that are highly likely to fall. Be aware of the hazard these trees may present. Saturated soils can also cause oxygen starvation by pushing water into areas where there is normally air in the root zone. Oxygen starvation can look like symptoms of other problems. To determine the real problem and what may need to be done, consult with a professional.

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