University of Vermont Extension
Department of Plant and Soil Science
Dr. Leonard Perry, Extension
University of Vermont
Starting your own flowers and
vegetables at home from seeds lets you have many varieties you might
otherwise at stores, can save you money, and is fun. If you are
thinking of starting more than a
few packs of seedlings, or already did last year and ran out of room to
them on prior to planting outside, you may want to think about buying
a home greenhouse.
First, ask if you need a small
greenhouse or some other structure? What
are you intending to grow? If you are
starting seedlings indoors under lights, perhaps all you need is a
instead to harden them off before planting out.
If growing vegetables, perhaps you'll just need some low plastic
over the rows. Yet most gardeners, if
starting more than a few flats of seedlings, will find a home
useful, fun, and a welcome setting in early spring.
Home greenhouses come in all sizes,
starting with small pop-up tents just for spring use (although I've
last fine in central and southern New England year round). These
can be about 4 to 6 feet wide by 6 to 8
feet long, and about 6 feet or so high.
For just a couple hundred dollars you'll be in business growing in an
hour or so.
Other greenhouses you leave up year
round, especially in colder climates. A
bit more sturdy and long lasting are those covered with plastic
film. Larger greenhouses, similar to those used by
growers, have a small fan inflating another layer of plastic on the
outside. This creates an air space
between layers for extra insulation. Such air-inflated houses usually
home grower wants
or needs, and harder to construct, with recovering needed every 3 to 4
I prefer, and have, a small
greenhouse made of a polycarbonate solid material. Unless just
growing during April and May, you
may want to get one that is "twin wall", having two layers with an
air space between. In cross section they
look like honeycomb. Even better for
insulation, but more money, are the triple wall glazings (the word for
Although solid, these polycarbonate
materials bend so can cover a curved, hoop frame. Or they can be
cut and used in sheets for
straight walls. These materials usually
last for at least 15 to 20 years before they begin to yellow and reduce
light coming through. Such glazings made
specially for greenhouses, compared to those that may look similar from
stores, often are treated on the outside to resist the UV rays from
and treated on the inside to reduce condensation that can build up and
Of course if you want a more
decorative greenhouse, such as attached to a home or building ("lean
to" greenhouse), you may consider glass.
This is harder to construct and deal with, can break, and unless twin
wall (similar to energy-efficient windows for homes) lets more heat
out. Glass greenhouses tend to be more expensive,
but maintained can last for decades.
If you're handy with tools and
building, you may want to construct your own home greenhouse.
Otherwise you may want to consider just
buying a "kit" with all you'll need.
You can then buy accessories such as heaters and benches. Some
even include these. If you'll be growing vegetables in the ground
you may not even need benches. There are
many suppliers of greenhouse kits online and in garden supply catalogs,
from some seed companies. These can be
located with an internet search for "home greenhouses" or similar.
If buying a home greenhouse kit,
some other considerations in addition to glazing type are where it is
from--is it suitable for a northern climate, and what is the freight
might even call
the company and, through talking with them, see if they can provide
answers to any
questions, and judge their customer service (if you have technical
once your greenhouse arrives it helps to have such expertise
handy). They should be able to give you tips on the
foundation needed for your greenhouse (often this is just wood anchored
ground), and how to make your greenhouse more energy efficient if
you'll use it
during colder months.
Unless growing just in April in May
in the north, you'll need a more powerful heater. Make sure the
greenhouse supplier can
recommend both type of fuel heater (common is propane), and appropriate
size. If you'll be growing during colder
months, on windy days, you'll need a much larger heater. It is
better to spend a little more now and
make sure you have enough heat if needed.
For the seasonal, tent types, an electric space heater may be all that
On the flip side is
ventilation. Larger greenhouses have
automatic vents and fans that run with electricity (although they
little). For smaller greenhouses consider
automatic vents that open and close on their own, just by expansion in
with no power. Invariably the greenhouse
will need vents open and closed, with the sun coming and going, to keep
getting too hot or cold. Even if you're
at home all the time, this can become quite an issue.
The main consideration when buying a
home greenhouse is the size. Just like
rooms at home, you can usually fill any available space and wish you
more. Buy the largest greenhouse you can
afford, and have space for. When
planning its location, allow space either for an addition or another
nearby. Make sure to locate near your
home (if not attached), near water and power, in full sun, and easily
accessible for moving plants and supplies.