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The Real Dirt Frost Protection Tips
by John Harmon
November 10, 1999

It's getting to the time of the season in the north where we have to start worrying about a killing frost. I have received a lot of requests for the information about floating ground covers that appeared in a column earlier this spring. Here's the information again along with some other cheap methods for keeping your plants from being frosted.

Row covers:

Floating row covers are very lightweight woven polypropylene that you can use to cover whole rows or your whole garden at night or anytime the weather turns cold. Row covers let in rain and provide good air circulation but they cut out some of the light so should be removed in the day. They breathe because of the way they are woven and are so light they won't crush new seedlings or mature plants. One brand, AGROFABRIC, lists its covers in four different weights. The lightest lets in 90% of the light and will protect down to freezing. It weighs point three ounces to the square yard. The next weight protects down to 28 degrees F. and weighs point five ounces to the square yard with 85% light transmission. The heaviest one protects down to 24 degrees F. and weighs only one point five ounces to the square yard and still lets in 50% of the light. They are not cheap but they last for years. The cover can be spread over a frame or just over the plants and held down with stones or dirt around the edges.

Here's a couple of places to get floating row covers. McConkey Company, 1-800-426-8124. These folks are in Sumner, Washington and the service is great by mail. They sell covers by the roll or will custom cut one to fit your garden. You can also get small rolls from Stokes Seeds in St. Catharines, Ontario. Phone-905-688-4300.


Clear plastic is not very good to protect your plants from frost. The frost forms on both sides of the plastic and will damage any plants touching the bottom side. If you must use clear or black plastic in a pinch make sure you support it with something so it doesn't touch your plants. I've used fresh poplar branches stuck in the ground on both sides of a row spaced every three or four feet to support the plastic. The problem I ran into is the wind kept taking it away hoops and all. It's also a hassle to remove the plastic or roll it up during the day. With the night frost and the high temperatures in the day it's a constant fight to keep a happy medium. With the cold nights and hot days you get a lot of condensation so it kind of rains under the plastic if you wait too long in the morning to take it off and that causes problems with mold and things like powdery mildew. Roll the plastic back as soon as it gets above freezing. With the wind we get I suggest nothing lighter than 6mill plastic and a few staples on the hoops doesn't hurt either.


Another option is covering crops like strawberries with of all things straw. Yep, they will be protected from the frost while those last few berries ripen and it breaths better so you don't have as many problems with mold and mildew. There are two problems associated with covering your strawberries with straw. I remember a rotten little kid of about seven who will remain nameless who was playing with a buddy at building campfires behind the shed, right next to a straw covered strawberry patch, helplessly watching as his campfire got away into the field. As the strawberries smoldered after the flash fire his hind end got a little warm too as I remember. The other problem is that mice like the cover and can sneak up on your strawberries unnoticed. They pack them away for jam in the winter. I use straw or old moldy hay to cover things like Oregano and you can still uncover and pick the herb fresh long after everything unprotected is dead. I've also buried garlic in the hay to give it that last couple of weeks to mature. Using old hay will give you problems with weeds from the seeds in the hay but I have lots of weeds already so I would hardly notice. Straw won't give you the extra weeds. By spring the straw has broken down nicely and can be gathered and tilled in to add humus to the soil or composted.


Don't forget newspapers. They work very well at insulating against the cold and in a pinch will protect things for a night. Just ask those folks who have slept under them before. I always seam to have that pile of newspapers by the door that was supposed to go but somehow was forgotten last trip or two to town. Spread a few layers deep loosely over your plants they give a fair degree of frost protection. They don't look real snazzy if you live in a high class neighborhood but if you live there you don't have that pile by the door when you need them anyway. The best part is you will have something to read as you remove the newspapers in the morning. Newspaper can also be shredded and composted. Check to see what kind of ink your newspaper uses first.

With a little luck and some planning you can keep the harvest going for a few weeks after that first killing frost.

John Harmon owns and operates Tropicals North. Write to John at: The Real Dirt, c\o 211 Wood St., Whitehorse, YT., Y1A 2E4 or e-mail

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