Our yard, thanks to my hubby, bursts with dahlia blooms from July to October. They are tender plants and a first frost can wipe them out. But because that initial frosty hit is often followed by a time of warmth, we cover the dahlias and other plants to see if we can extend the season just a little bit.
Last year, we were not prepared, but what we came up with in a pinch worked. Late in the afternoon on the night of the predicted first frost, I ran to a local store and bought light-weight, plastic drop cloths and a bunch of clothes pins. I've heard some say not to use plastic, but because we had so many rows of plants to cover, I opted for long rolls of very light-weight plastic drop cloths. You can also use fabric, such as sheets, light blankets, light towels or official frost fabric found at some garden centers. The University of Minnesota Extension website has information on various types of frost prevention covers, including row covers, tents and cold frames.
Before you cover your flowers, water them. Moist soil retains heat more effectively than dry soil. Next, you're ready to cover the blooms. If at all possible, do not let the plastic or fabric touch the plants. Creating space between the flowers and the cover material prevents moisture build-up or the weight of the fabric from causing damage. The idea is to trap warm air in and to keep the cold air out. We were not able to keep the plastic off of all the plants, and even though the covering was just on over night, some blooms took a hit.
The next morning, most of our 350 dahlias made it.
Potted flowers are easier to protect. If you can lift them safely (I'm doing a video with an athletic trainer next week on how to properly lift heavy items, so watch for that) bring them inside. If not, cover them.
There's no guarantee that your frost protection method will work. But when you live in the upper Midwest where the growing season is short, trying to extend the season a little longer is definitely worth the effort.
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