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It's Fall Clean-Up Time Again
by John Harmon
September 15, 2002

With the repeated frost the last couple of weeks it's clear that the garden season is over for another year. At least the outdoor part anyway. It will soon be time to close up greenhouses for the season too. With the loss of daylight production is going down rapidly. Here are a few things you can do this fall to make it easier to start your greenhouse up in the spring.

Every year I recommend that folks put together some mixed soil and bag it up for spring planting. I like to use "soiless mixes" and I mix up my own. Although pure vermiculite may be used for seeding, a more versatile soil-less mixture consists of one-third peatmoss, one-third perlite, and one-third good compost. Components should be thoroughly mixed and moistened with warm water several hours prior to using. Make sure you sterilize the mixture before you use it.

Moisten the mixture and heat it to 180F (internal temperature) for 30 minutes. Do this well in advance of when you plan to seed so it has a chance to cool down. Use a meat thermometer to determine when the soil has reached 180F. 180F will kill insect eggs and larvae, some weed seeds, and damping-off fungi. Avoid higher temperatures! At higher temperatures beneficial organisms are killed and dissolved salts are released from the soil which may be toxic to your young plants. Once it's sterile you can bag it up and store it away for spring or that houseplant that needs a bigger home over the winter.

For starting seed take the soiless mix and run it through a piece of window screen stretched on a frame. I just kinda rub the soil through the screen with my hand and it gives me a fine textured mix perfect for starting seeds or cuttings. The other option is buying a mix made specifically for starting seeds. I like Terra-lite Redi-earth, which is a fine soiless mix perfect for seedlings and it's cheaper than buying small bags of potting soil even at Wal-Mart prices.

The new weather forecast just out for September has the Yukon forecast to be near normal in temperature for the month. The new fall forecast has just about all of Canada predicted to have above normal temperatures and the forecast is for above normal precipitation in the south east of the Yukon. Northern Yukon is forecast to have below normal fall precipitation. The new winter forecast continues with above normal temperatures and above normal snowfall forecast for all of the Yukon.

The part of the forecast that concerns me is "above normal snowfall forecast for all of the Yukon". If your greenhouse is covered with plastic film and you don’t want to remove it you can protect it by covering the entire greenhouse with a plastic tarp. Besides helping the snow to slide off easier the tarp will protect the plastic film from the sun and it will last longer and discolor less. It’s the UV rays that damage the plastic and it’s easier to replace a tarp than to recover a greenhouse.

If you have one of those tubular metal framed greenhouses and don’t remove the plastic for the winter it couldn’t hurt to put in a few braces just in case we get as much precipitation this winter as we did over the summer. All that snow could be a heavy burden for the frame to support without a little help. It only takes a few poles and a little time but if there’s just one heavy snowfall it’s worth the effort. I had a steal frame greenhouse a number of years ago that collapsed from just one night of heavy wet snow. That event is what taught me to use a little extra support BEFORE the snow flies.

The good news is that if we do get more snow than normal it will provide good ground cover and any perennial plants or shrubs will have better protection from the cold and over-winter better. Unfortunately it will also provide a warmer haven for mice around your shrubs and trees. Mice can be very destructive over the winter eating the bark from trees and stripping perennial plants. This year there are mice everywhere. They are moving in anywhere and early.

To prevent mouse damage to trees enclose the base of the trunk with a cylinder of three-quarter inch mesh hardware cloth. Make the cylinder at least six to eight inches in diameter and extend it from about an inch below the soil level to the first branch. A less reliable protection from mice is to wrap the base of the trunk with heavy burlap.

These safeguards should successfully prevent mouse damage and reduce rabbit damage but when the snow is deep, rabbits can reach branch tips to eat so try to reduce the rabbit population by having a little stew now and then. Leaving pruned branches on the ground also reduces damage to living trees because the rabbits will chew the bark from the branches and leave trees alone.

Whatever the winter brings a little work now will make it easier when the snow finally melts and gardeners can get back to growing.

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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