Winter is coming to the Northern Hemisphere. Is your greenhouse ready? Prepare to make your plants snug this winter if you plan to heat your greenhouse. If you won't be using it this winter, now is a good time to clean everything thoroughly and make repairs so that you are ready for spring. If you need a professional to look at the exterior of your home before the winter months, Ohio Roofing Solutions is a great choice.
Remove any plants that won't make through the winter in your greenhouse. This depends on what temperature you plan to maintain in there. This is the last gasp for cucumber vines. If you won't be maintaining a minimum temperature of 60 degrees Fahrenheit this winter, the tomatoes won't produce. Out they go. (Pick off any fruit that has a "white star" on the blossom end. You can ripen those in a cool room or the garage.)
Pick up all leaves and any other plant material that is lying around. Don't leave anything in which pests might winter over. Compost everything except plants that have been diseased. Those should be destroyed. Everything should be neat. No strings, old plant tags or empty fertilizer containers.
Wash the glazing, frame and whatever you can reach of the benches with a mild liquid detergent diluted with water. If you have double or triple-wall polycarbonate glazing, be sure to wash "with the grain" (in the same direction as the channels) so that any scratches won't be obvious. Cleaning the glazing is particularly important if you will be using the greenhouse this winter. You want to be able to receive all possible sunlight. If you still have shading material on your greenhouse, remove it or wash it off.
If you have wood framework or benches, you might want to use a mild disinfectant. I have never found this to be necessary. We do not live in a sterile world. Thorough cleaning with detergent works for me.
Check to see the door latch works and that doors and vents swing freely.
Oil any metal moving parts. Replace any broken glazing.
If any of the plants are pest ridden, treat them now before you bring any more plants into the greenhouse. Also, any plants or cuttings that you winter over should be pest free before being brought inside.
Check all caulking in your greenhouse and replace with fresh caulking where necessary. Seal with caulk any seams, such as where glazing meets frame and where frame meets foundation. Don't caulk your vents closed! Sticky-back foam tape can be used to keep doors and vents draft-free when closed. Any ventilation this winter should be carefully controlled. You don't want a greenhouse full of air leaks that let in cold air and allow heated air to leave easily and constantly.
Especially if you have only single layer glazing, you will need to insulate. On areas that need to transmit light, use clear bubble type insulation or another layer of your present glazing. Be sure to seal around the edges well so that a "chimney effect" will not occur and draw warm air up and out of the greenhouse.
Everyone should insulate the north wall and roof of their greenhouse in winter (read "south wall" if you are in the Southern Hemisphere). Use special reflective greenhouse insulation, make it a nonglazed wall and insulate it conventionally, or cut panels of rigid foam insulation that will fit tightly on the north wall. Whatever you use, be sure that the inside of that wall is reflective (silver or white) so that any light entering the greenhouse will be reflected back on the plants.
The greenhouse foundation should be fully insulated. Any wall that is not glazed should be fully insulated.
If you live in an area with very cold winters, you should also insulate
the east and west walls and north roof. Additionally, at night you might
want to insulate even the south wall and roof to prevent heat loss. Don't
forget to keep your vents operational.
Unless you are confident that your water pipes will not freeze this winter,
drain the lines and use insulating covers on any outside faucets.
Whatever type of heating you use, be sure it's in working order before winter. If you need to calculate your heating requirements, go to this page.
Aren't all greenhouses "solar?"You may not have time to implement what you learn this year, but the weather will encourage you to find a way to make your greenhouse more energy efficient.
My definition of a "solar greenhouse" is one that uses the heat and light of the sun as efficiently as possible given the global location and siting of the greenhouse. This involves things that I've already mentioned such as insulating and covering the glazing at night. Other issues are the angle of your glazing and finding ways to store heat gained during the day so that it may lessen heating requirements at night--and much more. Maybe it's time to collect containers, large or small, to make a wall of water in the greenhouse. It will work just like those used to protect tomato plants, only on a larger scale.
Here are some recommended books on solar greenhouses. They may not all be in print, so check your local library or contact Powell's Books through their website.
Winter Greens - Solar Greenhouses for Cold Climates, edited by Mark A. Craft, distributed by Firefly Books Ltd., 3520 Pharmacy Ave, Unit 1-C, Scarborough, Ontario, Canada M1W 2T8 . (The favored book in this list.)
The Food and Heat Producing Solar Greenhouse - Design, Construction, Operation by Rick Fisher and Bill Yanda, publisher John Muir Publications.
Low-Cost Pasiive Solar Greenhouses - a design and construction guide by Ron Alward and Andy Shapiro, publisher Charles Scribner's Sons.
Saving money for having your own greenhouse by retirement: