Tagged: greenhouse overwintering

Overwintering in the Greenhouse

greenhouse snow loadOne of the things I enjoy most about spring is planning out my gardens for the season. However, it also used to be one of things I dreaded as I began to tally up the cost of buying new plants every year. Having a greenhouse has allowed me to overwinter all of my beloved container plantings, and some of my garden perennials that cannot survive the winters here in the northwest. I have put a great deal of time into designing and caring for the container arrangements around my house, and now I do not have to park in the driveway during the winter while I store them in the garage.

pot in potLast year I started using a pot in pot system where I buried larger pots in the garden that the perennials’ pots can fit into. This makes pulling them in the fall much less labor intensive and then in the spring I just put them back into their prearranged spot and cover both pots over with mulch. This has also allowed me to incorporate rare plants that are not recommended for my hardiness zone into my landscape. I know pride is a sin, but it is always satisfying when someone says, “How did you get that to survive? I tried and it didn’t make it through the first winter.”

Then I proceed to tell them about how my greenhouse has allowed me to really take my gardening to the next level. I opted to get the all season package that included a heater, motorized intake shutter, exhaust fan, and all the thermostats to automatically control them at the temperatures I set. To ice the cake it also came with a wireless weather station that allows me to monitor the temperature and humidity of the greenhouse from my kitchen. All I have to do is check periodically to make sure the pots do not get bone dry and the climate controls do the rest. I do not have to worry about pesky rodents, freezing, fluctuations in soil temperature, or dessication from being exposed to cold dry air because my plants are protected within the greenhouse.

Sunglo in AlaskaThere are only a couple of things to keep in mind when you set out to overwinter your plants in a greenhouse. In the early fall, I gradually reduce watering and fertilization and allow the plants to harden off outside until just before the first frost.This puts them into a state of dormancy and keeping the greenhouse temperatures between 45° and 55° F throughout the winter prevents them from coming out of it prematurely.This is very important because any undesired growth at such low temperatures will more than likely be weak and therefore highly susceptible to various infestations.

overwinter greenhouseThis is where a Sunglo greenhouse truly outperforms the competition. The exhaust fan, motorized intake shutter, and heater, all controlled by individual thermostats, ensure that the temperatures stay within the desired range. Most hobbyist greenhouses on the market use a paraffin wax piston to automatically open a vent of some sort. It is impossible for this type of passive ventilation system to maintain temperatures between a specified range.

sunglo snow loadDuring dormancy water uptake is dramatically reduced, but you must be careful not to let the soil get to dry. Just a slight dampness to the touch is sufficient. I considered installing a drip watering system on an irrigation timer this year, but decided against it. Colder temperatures and overly wet soil can spell certain doom for roots and the plants that depend on them. Instead I will continue to check them periodically and I suspect they appreciate the company.

overwintered plantsAs spring approaches I raise the temperature to between 55° and 65° F and gradually increase it from there. Some people prefer to keep the temperatures in that range until they move their plants out of the greenhouse to ensure they are hardened off. I have found that a strong oscillating fan and cooler night temperatures promotes strong enough growth for outdoor conditions. I also wait until I am absolutely certain there will be no more frost before I move anything out into the garden. I resume regular watering and begin an incremental fertilization schedule starting at half strength. By sometime in March I have the temperatures high enough to start spending some quality time in the greenhouse again and begin to germinate seeds, pot up the dormant cuttings I have taken over the winter, and get back into the business of what I love most.

I still enjoy planning out my gardens every spring, but with most of my plants all ready to go I now marvel at how much money I save. The question I am most asked is, “Isn’t the cost of heating the greenhouse throughout the winter more than the plants are worth?”  To which I always inwardly ask, “How do you put a value on keeping that which you love so much alive?” But in all honesty, being as serious a gardener as I am,  the unrivaled insulation of my Sunglo’s dual pane design keeps my energy costs well below what I used to spend on plant material every year. If you are interested in taking your gardening to the next level or have more questions related to overwintering please give us a call.