An excerpt from his book
ŇGreenhouse GardenerŐs CompanionÓ
All rights reserved.
Reprinted at GardenSmart TV web site by permission from the author.
GROWING for the HOME GARDENER
Shane Smith, Director of the Cheyenne Botanic Gardens
GardenSMART Episodes - Show 25
, Show 26
Varieties NOTE: This is a continuation of last weekŐs
have been many vegetable and flower varieties developed especially for
commercial greenhouses that sometimes are offered in regular retail seed
catalogs. These greenhouse varieties were selected mostly for the commercial
greenhouse grower in mind. They have been chosen for high productivity under
ideal conditions of light and temperatures in a totally controlled energy-intensive
environment. These varieties usually have the characteristics of disease
resistance, high yields, vining growth, bolt resistance (lettuce) and
resistance to physiological disorders (i.e., fruit cracking on tomatoes). In
the case of cucumbers, some varieties are labor saving because they don't
require any hand pollination in order to set fruit.
In better seed catalogs, these varieties are
usually flagged with a statement such as ''For greenhouse production'' or ''For
forcing.'' Forcing is a common European horticultural term used to describe the
forced growing of the plant out of its normal season. I always thought it was a
term that sounded like a Nazi greenhouse operation ''vee have vays to force you
Two catalogs that commonly list greenhouse
varieties are Stokes and Johnny's Selected Seeds. When you are
reading these catalogs, you could find the perfect home greenhouse cucumber
(sometimes called a European Forcing Cucumber) that does well in ''cooler
temperatures and is tolerant to powdery mildew.'' Here is where you apply what
you know about your greenhouse environment and your greenhouse's specific
problems with diseases in order to select the right variety.
Another way to find varieties bred for greenhouse
conditions is through your local commercial greenhouse grower. They might let
you thumb through their wholesale catalogs that only commercial growers use.
See if you can buy some seed through a local commercial greenhouse grower.
Greenhouse varieties are not available for everything, as you will find only a
limited number of crops. I hope that in the future, people will show the seed
companies that there is a large demand for these varieties. Maybe then, theyŐll
start breeding a whole slew of crops specifically for the home greenhouse and
even the solar-greenhouse environment.
Here are seeds and plants that have been developed
for greenhouse growing- Vegetables: certain herbs, carrots, cucumber, lettuce,
peppers and tomatoes. Flowers: Alstroemeria, aster, calceolaria, carnation,
chrysanthemum, cineraria, cyclamen, freesia, gerbera, ranunculus, rose,
snapdragon and stock.
Why not grow native wildflowers, asparagus,
rhubarb, cherries, apples, peaches, pears, apricots, currants or
raspberries in your greenhouse? The main reason that these crops are difficult
is that they are temperate crops used to an environment where the cold of
winter is not only expected but also required for natural growth. Without the
winter cold treatment, they would not produce properly. In addition, these
crops require an appreciable amount of greenhouse space, but produce for only a
relatively short time. In addition, depending on where you live, these crops
may do just fine outside and, unfortunately, won't do much better inside unless
you live where summer frosts are common.
Still, there are those who would be in total
heaven if only they could be eating fresh, homegrown rhubarb or peaches in the
winter. Well, with some effort there are ways to pull it off, although I'm not
sure if it is worth the effort. All you have to do is fool Mother Nature (which
is not always nice). You do this by faking a winter, or as horticulturists put
it, 'force' a crop.
Different crops and varieties have different chill
requirements, and these can be imitated artificially. One way to provide the
proper amount of winter cooling is to go outside in midwinter or early spring,
carefully dig up the desired plants (you may need a pick for the frozen soil)
and transplant them inside for late-winter harvests. I call this the
'half-winter' treatment, which is usually enough to ensure proper production.
Wintertime transplanting can be close to impossible with an 8-foot (2.4-meter)
peach tree, but with dwarf varieties in moveable containers on rollers, it
could be done more easily.
Growing of these winter-loving temperate crops in
a greenhouse warrants some further experimentation and development. There is
some good potential for growing crops such as asparagus and rhubarb in winter
greenhouses. In the South, plant breeders have actually developed varieties of
temperate crops that require less chilling in order to produce yields. If you
want to pursue this begin looking through the many available regional, southern
U.S. plant catalogs and you will occasionally find a low-chill requirement
As you gain more experience in the greenhouse, you
will find it is rare for the same fruit or vegetable variety that you grew
successfully outside to also do equally well inside. The climate in a
greenhouse is different and we need to approach it with that in mind. The extra
yields of vegetables and flowers make the reward well worth selecting plants
especially suited to the greenhouse environment.
The inside garden and the outside garden are two
different and special worlds and for the most part should be treated as such. It
is not more difficult or complicated to grow under glass. It is simply
Visit www.greenhousegarden.com for more
greenhouse resources, garden tips, and to order the book, 'Greenhouse
---Posted November 20, 2009---