Q: To greenhouse or not to greenhouse?
I have always wanted a greenhouse. I live in the Bay Area on the east side of the Berkeley Hills. We have a few days to a week of frost in our area. My (very hilly!) lot is filled with old oak trees, some of which are deciduous. Shade is plentiful. Sunlight hard to come by. My primary purpose in getting a green house is to start seeds in December and January, when frost is likely, and again in July, when things are hot.
So I have some questions.
1. Where will the greenhouse go? I am thinking a corner of the lot which is shaded by deciduous trees would make the most sense — light in the winter, cool in the summer.
2. Will the unheated greenhouse provide sufficient warmth in the winter? It would be on the slope of a hill, most likely,
possibly near the house. We don’t see much frost there.
3. Is on the north side of a redwood, close to the house, under a huge deciduous oak a good choice? Or should I pick a sunnier spot?
4. Would I have enough frost protection to grow something tropical?
5. Will seeds sprout in the shade in the summer and develop normally without being leggy from lack of light?
Any advice about greenhouses would be greatly appreciated! I do see one or two around the neighborhood, so I think it is possible.
Tags: 'greenhouse newbie', greenhouse, shade
August 3rd, 2009 at 10:16 am
From my limited greenhouse experience, your scenario #1 sounds best. When starting your summer veggies in the winter, the more sun the better. I also found that bottom heat for the root area was just as important. I use the electric heating cables that Peaceful Valley sells. For winter veggies, Eastern exposure would probably be good or by covering the greenhouse with 30 or 47 % shade shade cloth. It’s best if they stay cooler with good light so they don’t bolt too early. Tropicals in a winter greenhouse should be no problem in your area. Also, look into the books Greenhouse Gardener’s Companion & Four Season Harvest.
August 5th, 2009 at 10:45 am
I agree with Linda, but to address each question you had:
1. The greenhouse should go where you have the most sun in winter. Secondary considerations would be access to water and electricity. You can make your own shade with shade cloths if you need to, take the most sun you can get in winter. Your tree idea is a good one and I have seen that recommended.
2. It’s hard to say if an unheated greenhouse will be “warm enough”… what is warm enough? If there is no frost or just light frost, plants will survive. Seeds need certain temperatures to germinate so you will want to meet those needs. Plants need certain soil and air temps to grow vigorously, you’ll want to meet those needs too. Your actual outside temperatures, the kind of green house, the location and sun exposure, the plants you want to grow and what stage of growth they are in… all contribute to answering that question. That being said… if you don’t see frost very often and you get good sun, you should be able to start veggies earlier, you may need to heat to germinate however.
3. I’m not sure I understand this location… “On the north side of a redwood” would lead me to think that the redwood would be blocking the sun that will be to the south in the winter. If this is true, this spot would no be good.
4. (see #2), think about what your definition of tropical is… the Nursery at Peaceful Valley had banana trees for awhile that were hardy to zone 5 (that’s zero degree temps)… you should be able to do any tropicals in the greenhouse and you may be able to do some tropicals in your yard.
5. Seeds germinate with the right soil temp, not with the right sun… the sun may cause the soil to get to the right temp, but it’s the soil temp that matters. Once they germinate and are “seedlings” then they need the sun. I second the shade cloth suggestion by Linda, it allows some sun through while lower the temp. You can also set it up to only shade plants for part of the day.
Other greenhouse stuff:
Consider the importance of having water and electricity to your greenhouse. With those two things you can have all your bases covered and even automate your house (thermostat, watering timer, misting timer, etc).
Venting your house: On hot days temps can soar into the hundreds… this dries out and harms plants. Vent’s release the heated air and let fresh cooler air in. Peaceful Valley sells two types of greenhouse vent openers that work without any electricity. These vents will open when temps get hot and close when temps get cool using what is basically a wax mechanism. These vents are reliable and can open a pretty heavy vent.
Table heat vs whole house heat; if you end up needing heat start with heating below the tables (as Linda suggests), then move to heating the whole space (air) second. Heating the tables or the bottom of the planting container is cheaper, easier and more efficient than heating the air in the whole room.