Late spring freeze: Will it impact your plants?

This season has been off to a bit of a rough start as we have seen one of the top 10 coldest starts to astronomical spring ever recorded. Since the start of meteorological spring on March 1, temperatures have fallen below freezing for 21 days, with 10 of those within the month of April. Late freezes can have a big impact on plants during the growing season, especially if a brief warm up provides the opportunity for early budding. Unfortunately, this is the setup that we have encountered across mid-Missouri. We saw a brief warmup April 10-14, which allowed for many trees and plants to blossom. This could make way for some issues as below-freezing temperatures still look possible in the days to come.

Typically, the average last freeze occurs around April 10 for mid-Missouri. This is the date where we can typically expect our final freeze. With each passing day after this point we see a lower chance of temperatures dropping below freezing. By April 23 there’s only about a 10% chance of a final spring freeze after this date. This is the best time to begin planting. However, keep in mind that the latest final freeze ever recorded in mid-Missouri was May 5 in 2012.

The last freeze isn’t the only factor in determining successful plant growth. There are many other aspects that can go into play. Often times it may not even be a huge deal if the final freeze is late in the season. A better indication could be how many sequential freezes we see early on in springtime. A single, short-lived, late freeze could only cause a minor setback to plants. Whereas, a prolonged span of extreme weather could cause irreversible damage that could kill or severely impact the growing process.

Another thing to consider, is how far along the budding process is. Like previously mentioned, if a warm snap allows for plants to begin to flourish, a preceding cold snap could kill the plant for the season. If buds are small enough and just beginning to open, a single frost shouldn’t hurt the plant much; however, flowering buds are much more tender and prone to damage. Once buds form on flowering plants even one single frost or freeze could “nip it in the bud’– quite literally.

A light freeze is considered when temperatures drop from 29-32 degrees. A moderate freeze is when temperatures drop from 25-28 degrees, and the worst, a killing freeze is when temps fall below 25 degrees. Plants begin to show impacts under a moderate freeze, with a likely chance of dying under a killing freeze.

There are a few things experts recommend you do to help save plants and flowers from bitterly cold spring temperatures:

–Bed properly: Most plants need at least 4 inches of natural mulch, while staying clear of other roots.

–Place plants on the north side of home: This may seem misleading, as it is typically colder on the north end of your home. However, if you place your plants on the south side, the warmer environment will support earlier budding, which will in turn make your plant more susceptible to the harmful impacts of a late freeze.

-Blanket your plants at night: This will protect sensitive plants from the chilly wind and will also help prevent frost formation overnight.

-Provide plenty of water: A deep watering could help prevent freeze damage, especially after a dry winter. Moist soil will absorb the sun and heat from the day, which will help keep the plant warmer at night.

-Avoid immediately pruning damaged plants: Cutting damage too soon could lead to new budding, which could die off again in the event of another cold night.

-Provide more support: Allow any damaged plant to repair itself by providing structural support, deep waterings, as well as fertilizer to nurture it back to health.