FROST & FREEZE! OH NO!
Frost doesn't have to be scary because we can prepare! As the cool weather approaches, we all need to start looking out for our veggies, annuals, and newly planted trees, shrubs, and perennials. The terms ‘frost’ and ‘freeze’ may seem similar, but they are not the same!
THE DIFFERENCE
Frost occurs when temperatures drop to 31-33 °F, which can cause foliar and floral damage to many tender plants and warm season crops such as tomatoes and peppers.
Freeze occurs when temperatures drop below 26-31 °F, which can cause internal damage to the plant. Some of your cool season crops, such as lettuce, broccoli, and cabbage can withstand these colder temperatures for a few hours but may not be able to for extended periods of time.
DAMAGE SYMPTOMS
Symptoms of frost damage include crunchy or burnt looking leaf and flower edges, and a drooping look.
Symptoms of freeze damage include burnt looking leaves and flowers, a water-soaked or wilted look, and sometimes even causing the leaves to turn black.
The symptoms can seem similar, but knowing the outside temperature should help you identify what caused the damage.
THE SCIENCE
To understand the science behind it, we have to think of the anatomy of a plant. Plants have two ‘veins’, Xylem and Phloem. Xylem is used to carry water from the roots to the top of the plant. Phloem is used to carry sugars and other nutrients produced by photosynthesis from the leaves to other developing areas. When the water in the Xylem freezes and then thaws, it can cause damage to the plant cells due to Embolism. This is where gas bubbles form during the freezing period and then expand during the thawing period, causing water transportation loss and reduction in photosynthesis productivity. These side effects can be detrimental to the plant.
LET'S PREPARE
There are a few ways to prepare for upcoming frost and freeze events. You just have to decide what will work best for you and your space.
MOVE INDOORS
If you can, this is the easiest way to protect your plants. During a frost, moving the pots into your garage, a shed, or popup greenhouse can also be very effective. This will keep frost from forming on your plants and causing damage, even if the temperature is colder.
COVER PLANTS
Before dark, cover plants with a blanket or sheet to insulate them and trap daytime heat, using bamboo stakes or poles to prevent crushing and bricks or stakes to secure the cover in wind. Be sure to remove the cover in the morning or once temperatures rise to prevent overheating.
WATERING
Water your plants well the day before! Water temperature cools slower than air temperature, so having moist soil can act as insulation.
USE MILK JUGS
You can cut the bottom off a milk jug and use it as a cloche or small greenhouse. This will trap in some heat and protect against frost forming on the plant.
