Enjoy a Fall Harvest of Vegetables

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Using a soil thermometer can help insure germination.
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The author displays a basket of her succession planted autumnal harvest: carrots, Jerusalem artichokes, brussels sprouts, radishes, and broccoli.
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You can harvest vitamin-rich carrots right up through Christmas.
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Tasty Jerusalem artichokes will stay crisp all winter under their blanket of snow and soil.
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The author displays a basket of her succession planted autumnal harvest: carrots, Jerusalem artichokes, brussels sprouts, radishes, and broccoli.

If you’re like most gardeners, you probably plant a few
late crops each summer (more as an afterthought than
anything else), but perhaps you’ve never seriously
considered coaxing a fullsecond harvest from your
vegetable plot. I know I never gave the possibility much
thought … until one autumn morning when my shovel hit a
12-inch-long white radish (of the oriental Dalkon variety)
buried deep in the still warm earth. That delectable
vegetable inspired me to systematically plan and cultivate
a late fall harvest in my backyard plot.

Since the “day of the Dalkon,” I’ve learned (mostly by
trial and error) how to nearly double my annual
harvest–even here in Minnesota, where the growing season is
quite short–by starting a second crop during the hot
weather months. And you can enjoy the same success …
with just a little planning and careful attention to the
details that make late summer and fall planting different
from spring sowing. 

The Drawing Board

Any venture into three season gardening should begin with
thorough planning … including seed selection and a
“blueprint” plan to fit your particular growing season. If
you’re not sure of the dates of the last killing spring
frost and the first autumn freeze in your area, the county
agricultural extension agent can provide you with the
information.

You might be surprised to find that the length of your own
property’s frost-free growing season is different from that
of even your closest neighbor’s land … because of
variations in the terrain. As you know, warm air rises … so a hilltop garden is encouraged to produce abundant
harvests both early and late in the season. On the other
hand, the cooler air in valleys (especially those with
spring-fed streams) may surround a lowland garden with a
cold and clammy atmosphere that’s not conducive to either
early or late cropping.

Although it’s hardly practical to move your family to an
area with a longer growing season just to be able to try
succession planting, you can make some onsite
adjustments that will help you grow late crops
successfully. First of all, be sure to locate your garden
where it won’t be shaded by tall trees … which rob the
young plants of sunlight and soil nutrients. It’s also a
good idea to place your vegetable plots on the south and
east sides of buildings … or to protect the crops from
punishing north winds by putting in shrubs (or another type
of low windbreak) along the garden’s vulnerable edge. You
might also want to plant your early and late crops toward
the top of a slope, or in raised beds. 

Do Your Homework

Once you know the limits of your frost-free season and have
chosen a site for your garden that will make the best use
of that time period, you’re ready to pore over the seed
catalogs. You will, of course, need frost-tolerant
vegetables in order to extend your garden’s productive life
into the autumn. Hints in catalog descriptions, such as “sown
in early August for fall crops” … “will increase in
eating quality into late fall” … and “best in September
when nights are cooler,” will help direct you to the proper
selections.

You should choose only the hardiest cultivars (those that
can survive a minimum temperature of 26°F) and
those that mature quickly … especially if you live in
the upper part of North America. A short season cabbage,
for example, might have a better chance of coming to
harvest than would a slower growing “main crop” cabbage.

You’ll find all kinds of robust vegetables in the catalogs
of seed companies catering to a northern U.S. or Canadian
clientele … since such firms often specialize in short
season crops that are ideal for succession planting. Here
are some reliable companies to try: Stokes Seeds, Inc; Farmer
Seed and Nursery; and Johnny’s Selected
Seeds. (The last one is an
especially good source of late producers. The firm’s fine
catalog features such prime midseason and fall crops as
Lutz Green Leaf beets, Scarlet Keeper carrots, Wando peas,
and Danish Ballhead cabbage.)

Once you’ve narrowed down your preferences to a few
specific varieties, it will be helpful to draw up a
Succession Planting Sow-Harvest chart. On paper, you can easily
shuffle and rearrange the garden rows like puzzle pieces … as long as you keep in mind the approximate sowing and
reaping dates for each crop. For instance, you might like
to try an early lettuce, succeeded by midseason carrots … or follow an early cabbage with a late
beet. Most horticultural experts recommend planting
a root crop after a leafy vegetable, in order to balance
the supplies of the different nutrients that each type of
plant removes from the soil.

Charts formulated for the cold
climate of Zones 3 and 4 can be modified to fit the
growing season in warmer locales by simply adding time to
either end. You may have to adjust
your master plan to adapt to an unusually late spring or an
unexpected cool spell, as well. (I always allow an extra
week for each crop, anyway … to accommodate any
unforeseen weather changes.)

When you formulate your succession planting schedule,
remember to take advantage of some of the newly developed
hybrid cultivars, many of which mature in significantly
shorter growing periods than do older types. The 1979 All
America Grand Duke hybrid kohlrabi, for example, will
mature five days sooner than would previous varieties of
the vegetable … and five days can be quite significant
for gardeners in cooler climates! 

Seeding and Transplanting

No matter what zone you live in, you’ll find that planting
a fall garden is quite different from spring sowing …
since the late year cropper has to deal with less than
favorable conditions. The soil at mid-season is warm and dry
(and already depleted of many nutrients by the earlier
crops), and transplants aren’t readily available from local
nurseries once summer is well established.

Most of my early attempts at planting for autumn harvest
ended in failure … simply because I didn’t know that
seeds have maximum as well as minimum germination
temperatures. The optimum soil temperatures for sprouting
many cool season vegetables are well below 80° F. (For
example, endive, lettuce, and spinach germinate spottily if
at all in soil that’s warmer than 75° F.)

To deal with this problem, use a soil thermometer (as I do)
to determine when your garden’s ground is registering above
the maximum germination temperature for a particular seed.
If the soil gets too warm, you can temper the
planting environment by covering newly seeded rows with a
board or straw bale (as insulation against the summer sun),
by planting in the shade of a tall crop (such as pole beans
or sweet corn), or simply by sowing pre-sprouted seeds (you
can germinate them yourself in a sprouting jar placed in a
cool cupboard).

If your fall garden plan requires that you set out
plants–in order to harvest a mature crop before midwinter–you may be able to find the “starts” you need at a local
nursery … however, many garden centers overlook the
needs of autumn agriculturists, so you’ll probably have to
place a special order earlier in the season. Should you
decide to grow your own second crop transplants, on the
other hand, a cool basement equipped with a grow light will
serve as an ideal environment for nurturing young
seedlings.

A botanist once showed me how to stretch my garden’s
production of tomatoes long past the normal season by
propagating midsummer suckers. To do this, I simply soak
the trimmed young tomato shoots in a bucketful of warm
water for four to six hours before planting them. Such July
transplants will produce large, healthy vegetables long
after the regular vines of summer have been exhausted. 

Vegetable Cultivation

With April showers only a distant memory, you’ll probably
have to spend a lot of hours watering your late summer
plot. However, if you don’t want to become a slave to the
August seedlings, use mulch or a covering of straw to help
retain soil moisture. (I use a mulch mixture made of one
part soil and one part compost.

You’ll also need to fertilize your mid season
crops generously, since they begin their garden lives in
soil whose nutrients have been depleted by the previous
crops. But transplants will respond with lush growth if
they’re initially watered with a high-phosphorus rooting
solution and then side-dressed with a balance fertilizer (I
just use whatever manure is handy). Always make sure you
side-dress away from exposed plant parts, though … to
avoid fertilizer burn.

It’s a good idea as I mentioned before to rotate leafy and
root crops, in order to balance the food supply in the
soil. I also like to plant some kind of peas or beans at
regular intervals in each row since legumes collect
nitrogen from the air and transfer it to the soil. 

Getting Ready for Spring

Even your lush, extended fall harvest has to end, however … and finally the hard frosts of early winter will take
their toll. That’s your signal to “close u shop” and
prepare your garden for spring planting. I usually convert
all of the healthy plant residue to compost … an then I
till pony and chicken manure into the plot to replenish the
soil. (The late plowing is also good for turning up pest
eggs and larvae … and exposing they to winter’s killing
temperatures.)

I work several rows smooth, in order to have them ready for
planting early or ions, peas, spinach, and radishes.
However, several late fall crops–such as sprouts, carrots,
beets, and kale–often survive until Thanksgiving (even up
her in Minnesota!), so their furrows have to wait
until spring for soil preparation.

As you can see, a midsummer sowing of seeds and transplants
will, with careful planning and culture, mature into
delicious vegetables for late-season eating. When the new
seed catalogs begin to arrive in December, I’m usually just
harvesting the final produce from my midseason garden …
and it’s already time to start planning spring crops! It
seems as though the work/fun never ends … but that’s
just a happy fact of life for three season gardeners!  


Succession Planting Sow-Harvest Chart

April         May      June      July     August
-----------------------------------------------------------
Onions (100)                                Lettuce (45)
Lettuce (45)           Carrots (60)
Spinach (43)           Chinese Cabbage (71)
Beets (34)             Broccoli (55)
Peas (65)                         Cauliflower (48)
Broccoli (55)                     Kohlrabi (45)
Cabbage (61)
              Early Corn (53)               Spinach (43)
Table Onions Corn (83)
Kohlrabi (45)          Beans (42)