INTRODUCTION
Shane
Smith is this week's guest writer.
Even though Shane talks about selecting the right plants for use in a
greenhouse, his information benefits all gardeners, whether indoors or
out. Shane Smith appeared on
GardenSMART'S episodes 25 and 26.
This is an excerpt from his book Greenhouse Gardener's Companion,
�2000 & 2009. All rights
reserved. Reprinted at GardenSMART.TV web site by permission from the author.
---Anne K Moore---
GREENHOUSE GROWING for the
HOME GARDENER-Part 1
SELECTING THE RIGHT PLANT
FOR HOME GREENHOUSE GROWING
by Shane Smith, Director of the Cheyenne Botanic Gardens
GardenSMART
Episode 25 2009
GardenSMART
Episode 26 2009
Selection for Fruit and
Vegetable Shape and Size
When a plant grows vertically, it can make better use of unused
air space. If you are growing vegetables or flowers, vertical growing might
mean more of both for you to enjoy. Because the growing space in a greenhouse
always seems to be limited, it is sometimes wise to grow vining or vertically
growing varieties as opposed to bushy varieties. When it comes to vegetables,
there are many types that grow both bushy and low, or tall and vining. These
include peas, beans, cucumber, squash, melons, figs and bananas. Tomatoes are
also included in this list, but horticulturists have a special vocabulary for
them that might pose some confusion. Bushy tomatoes are called determinate
because they grow to a determined height and then the main leader on the plant
quits growing. Tomatoes that grow tall and viney are called indeterminate.
That is because they can grow indeterminately, given the right growing
conditions.
Bushy
vegetable varieties can fit into special places in the greenhouse or sunroom,
like next to a knee-wall with little headroom. But, one of the best places to
use bushy varieties is in pots. The tall vining varieties grown in a pot might
quickly get out of balance, with too much top supported by a small, limited
root system. This will cause the plant to wilt at the slightest provocation. It
will also be under constant stress, which is an invitation to every bug and
disease in the area. This type of plant stress can be avoided—just make
sure that the pot or container corresponds to the size of the mature plant.
Grow the big indeterminate tomatoes in tubs or beds.
I
have had great luck growing bush beans in hanging baskets. I like to grow bushy
determinate tomatoes in 1- to 5-gallon (3.8- to 19-liter) pots and have had
decent yields. Play around with bushy vegetable varieties in pots, and you�ll
see that it works great.
Selection for Disease
Resistance
The
inherent high humidity of greenhouses and intensive plant production can bring
conditions that promote plant diseases. Diseases are rarely controlled with
chemicals and are not recommended. The best defense against disease is to
maintain healthy plant growth. But you can also help things out by selecting
varieties that show some tolerance or resistance to a particular disease
problem. This is where you need to really study the seed catalogs and look for
any listed "resistance to disease." Before you start, it is important to make
every effort to identify your disease problem. There are many good books and
web sites on plant diseases as well as good resources through your local
university. Your county agricultural extension agent can also be helpful in
identifying a particular disease problem.
Many
plants show variability in their resistance to diseases. For instance, I had a
problem with powdery mildew affecting squash and cucumbers. Powdery mildew is a
white powdery fungus growth that covers the leaves and slows growth. I went back
to the catalogs and found varieties that were listed as resistant to powdery
mildew. By just changing varieties, I was able to see about an 80 percent
reduction in the disease without doing anything else to control the mildew.
What
the catalogs won't tell you is that even though a plant may be listed as
resistant, that degree of resistance may vary a good deal, from totally
resistant to only slightly more resistant. Don't be surprised if you are
growing a variety that is listed as "resistant" to a certain disease and still
see evidence of the disease. The variety may be only more tolerant than other
varieties.
You
may discover that some varieties have some resistance to a disease, even though
it is not listed as such in the catalogs. For this reason, don't put all your
eggs in one basket. Try to grow more than one variety of a particular crop, and
nature's genetic diversity will work for you. Then with a little experience
under your belt, you will have identified superior varieties. Good record
keeping is helpful in determining what worked well and what was mediocre. Don't
be lazy about being a good observer and take the time to make a few notes. It's
not hard and the reward? Having healthy, productive plants. Sometimes you have
to figure things yourself as this valuable information not available anywhere
else.
Selection for Insect Pest
Resistance
Plant
varieties that exhibit resistance to insect pests are rarer than those
resistant to disease. Breeding plants for insect resistance seems to be harder
to do. The better catalogs will occasionally mention some resistance to bugs,
but usually you have to learn on your own, as some plants are naturally more
resistant to bug attacks.
A good example of selecting for pest resistance happened to me
with lettuce. I used to grow a light green Grand Rapids lettuce variety called
"Slo Bolt." It was a good producer in winter, spring and fall but it was
readily attacked by both aphids and white fly. Then I switched varieties to two
newer, related lettuces: Green Ice and Royal Green. The major difference was in
the color of the leaf. Instead of having light green leaves these were
decidedly darker green in color. I found that the bugs were much less attracted
to the darker green lettuce varieties. For some reason the bugs just loved the
color of the lighter green plants. This simple change in varieties made a huge
difference in my bug problem.
Don't
expect that just by changing varieties, you will totally eliminate a bug
problem. It can help. Again, keep records. There may be other reasons for a
crop's insect tolerance besides just the color of the leaf. Be observant. Watch
the changes year to year among the varieties to be sure a change in bug
infestation is truly because of a change in varieties and not because it might
have been a bad year for bugs (yes, bugs can have good years and bad years).
Visit
again next week for more information on choosing varieties for the home
greenhouse and for growing in the cold months indoors. HOME GREENHOUSE GROWING
for the HOME GARDENER, Part 2, next week at GardenSMART.com
Visit
www.greenhousegarden.com for more
greenhouse resources, garden tips, and to order the book, "Greenhouse
Gardener's Companion".
---Posted November 13,
2009---