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  • From: "TradingPostPaul" <tradingpost@riseup.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Use Cold Frames to Grow More Food
  • Date: Sat, 24 Nov 2007 12:32:50 -0700


Use Cold Frames to Grow More Food
http://www.motherearthnews.com/Organic-Gardening/2007-12-01/Garden-with-Cold
-Frames.aspx
December 2007/January 2008
By Barbara Pleasant, Illustrations by Elayne Sears

Sow seeds in simple frames to add more than a month to your spring garden
season.

Gardening guru Eliot Coleman asserts that “the basic cold frame is the
most dependable, least exploited aid for the four-season harvest.” We
couldn’t agree more. Last winter, my humble box built of 2-by-4s topped
with an old shower door added a month to the front end of salad season, but
the best part was being able to sow some of my spring seeds directly into
the frame. This made more space available under lights indoors for tomatoes
and other crops that don’t like chilly conditions, and eliminated the
hassle and setbacks involved with hardening off seedlings and then
transplanting them. Best of all, seedlings get a nice head start in real
sun so they never get stretched out and leggy as they often do when started
indoors. (Indoor grow lights are vastly less intense than real sunlight.)

What can you sow in a cold frame? In spring you get a boost with virtually
any crop by sowing into frames. The list of “Top 12 Winter Cold Frame
Crops” (below) can get you started, and as days get longer and warmer in
spring you can try your hand at framing up peas, bulb onions, potatoes or
even tomatoes. When a cold frame is no longer needed for a crop that is up
and growing, simply move it to a new location and plant more seeds.

Traditionally, gardeners have used cold frames to harden off seedlings
started indoors, and you should have a frame suited to this purpose. But
one cold frame is not enough. In addition to direct seeding some vegetables
right where they are to grow, you can use a cold frame to winter-sow
onions, cabbage or other hardy crops that are easily lifted and
transplanted into rows.

A cold frame can be a wood box with a recycled window (or shower door) top,
a hay bale enclosure covered with plastic, or you might build one with
bricks or concrete blocks and top it with translucent corrugated fiberglass
(see “Anatomy of a Cold Frame,” below). Your frames need not be all
alike, though having two of the same size makes it possible to stack them
for added height. I like frames I can move around by myself without
straining, so size and weight are important considerations. If you live
north of Zone 6, you may want to create frames that are large enough to
accommodate black, water-filled containers for solar heat storage, and
insulate the sides by adding a snug berm of soil or mulch. In climates with
chronic winter cloud cover, you can maximize available light by painting
the interior walls of your frames bright white, or by covering them with
heavy-duty aluminum foil.
How Cold Frames Work

Cold frames shelter plants from ice, snow and treacherous winter winds, and
heat up the soil whenever the sun shines. The soil inside a frame will warm
up much faster than open ground, and because seeds of many hardy vegetables
can germinate in the 50 degree range, a three-day spell of mild weather
often coaxes them to life. Weed seeds will germinate alongside the seeds
you plant, but you will see far fewer weeds if you cover the soil’s
surface with a 1-inch-deep blanket of potting soil (purchased or homemade).
Be prepared to add water as needed to keep the soil from drying out.
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After seeds have begun to grow inside the frames, the plants are
surprisingly cold tolerant. I have watched lettuce seedlings sail through
10-degree nights when the frame was covered with a thick polyester-filled
blanket, and framed-up spinach never sulks no matter how cold it gets. Yet
these and other winter-sown vegetables will complain if a frame is allowed
to overheat, so it’s crucial that frames be opened to vent out excess
heat. When in doubt, it is always better to vent than to risk frying your
plants. If you can’t be around to open and close your frame and a warm
sunny day is in the forecast, covering the top of a closed frame with a
light-blocking blanket for a few days is your safest strategy. If blustery
winds threaten to sabotage your venting plan, place a board over the box,
between the frame and the top, to keep it from slamming shut. Or use hooks
and eyes to fasten the open top to posts sunk into the ground alongside the
frame.
Climate-controlled Frames

Any cold frame will harness solar energy for your plants’ benefit, and
there are several low-tech ways to help your frames retain solar warmth.
Black antifreeze containers, milk or kitty litter jugs painted flat black
can be filled with water and tucked into the corners. Or you can cover the
spaces between plants with flat stones painted black or “solar
pillows”—used freezer bags painted black and filled with water. If you
want to get more sophisticated, check into the Solar Pods and Solar Cones
developed by New Hampshire gardeners Leandre and Gretchen Poisson.
Described in detail in their book, Solar Gardening, and in Mother’s
online Archive, the Poissons’ devices are probably the best you can
build, if you can afford the materials. The superior performance of these
garden appliances comes from the use of Sun-Lite flexible fiberglass, which
costs about $80 for a 4-by-8-foot piece.

Historically, gardeners have used the warmth generated by rotting manure to
turn cold frames into hot beds. To make a hot bed, dig a hole inside your
frame at least 12 inches deep and fill it with fresh horse manure mixed
with straw, and topped with 6 inches of soil. As the manure decomposes, it
releases heat into the frame.

But you don’t have to have fresh manure to build a hot bed—or at least
a warm one. For example, let’s say you want to winter-sow broccoli,
spinach or another crop that needs abundant nutrients. If you dig out a bed
and refill it halfway with compost mixed with the cheapest dry dog food you
can find (a sure-fire compost activator), and then top it with 6 inches of
soil, the compost will generate enough heat to keep the little plants from
freezing and thawing quickly—if they freeze at all. In spring, when the
plants’ roots find the buried treasure deepin the bed, you may be looking
at the biggest, best plants you have ever grown.

Another option is to use the warmth generated by rotting hay to heat your
cold frame from the sides. If you have plenty of space available and you
plan to mulch with hay or straw this season anyway, go ahead and get four
bales and arrange them in a semicircle on ready-to-plant ground, with the
open side facing south. Plant the middle, and then top the bales with a
wide sheet of plastic stapled to two 2-by-4s; one board will lie atop the
back bales, and the other will anchor the plastic to the ground in front.
You can make a bigger hay bale haven by arranging seven or eight bales in a
square, and topping the enclosure with an old window, glass door or piece
of sheet vinyl or corrugated fiberglass. Or, make your bales go twice as
far by breaking them in half and encircling your planting with half bales,
set side by side with their cut sides out. Allow the broken bales to get
nice and damp before you plant, and then cover the bed and bales with a
large piece of plastic sheeting. As the wet hay decomposes, much of the
heat it releases will stay inside the bed.

To prepare a hot bed, warm bed or solar-charged cold frame when the soil is
frozen, simply place a closed frame over the spot for several days. Daytime
heating will thaw the soil inside, an inch or two at a time.

Various types of cold frames are multiplying like rabbits in my garden.
With the help of the frames, spring now comes to my garden at least six
weeks ahead of schedule.

Top 12 Winter Cold Frame Crops

These 12 vegetables are easy to grow when sown in cold frames in late
winter.

* Arugula
* Broccoli
* Beets
* Cabbage
* Chard
* Chinese cabbage
* Green onion
* Kale
* Lettuce
* Mustard
* Radish
* Spinach

Milk Jug Seed Starters

This simple technique was developed for seeds that need to spend a winter
outside before they will germinate, but it’s also a great method to start
garden seeds in late winter if you don’t have indoor lights or a cold
frame.

1. Cut a gallon milk jug (or other large plastic container) in half
horizontally, leaving one edge intact to use as a hinge. Discard the cap.
2. Punch several drainage holes in the bottom.
3. Fill the bottom with 3 inches of potting soil, moisten well and plant
your seeds.
4. Fold down the top cover, and secure the cut seam with duct tape.
Enclose the planted jug in a large clear or opaque plastic bag (such as a
produce bag), held together at the top with a twist tie.
5. Place in a sunny, protected spot outdoors.
6. One week before transplanting, harden off seedlings by removing the
bag and tape, and propping the jug open with clothespins.

Anatomy of a Cold Frame

Site Surface: Frames work best if the top is angled slightly toward the
winter sun. You can either cut slanted sides (see illustration, Image
Gallery) or, as an alternative, mound soil as needed to make the back edge
of the frame sit slightly higher than the front.

Frame: Scrap wood or untreated 2-by-4 or 2-by-6 pine boards are fine, or
you can upgrade to rot-resistant cedar, redwood or locust or composite
plastic lumber. Other options include logs, baled hay or straw, bricks or
concrete blocks.

Corners: If you only have a hand saw, a hammer and a screwdriver, you can
build a sturdy box from 2-by-4s, a few screws and four steel corner
brackets. Brackets come in different forms—some for inside the box and
some for outside. The simplest (and cheapest) ones screw into the top of a
frame that’s already been banged together with 3-inch box nails.

Covers: The best materials for topping cold frames are tempered glass patio
doors or shower doors, which often are discarded when homes and apartments
are remodeled. Heavy enough to resist strong winds, shatter-resistant
tempered glass doors are better scavenger hunt treasures than standard
storm windows or paned windows, which can be a safety hazard. Look in
thrift stores (Habitat for Humanity often sells donated doors), or call
people in home remodeling or salvage businesses. Look for doors that still
have plenty of hardware attached, and leave the hardware intact as you
scrub down your prize. Later, after you’ve built a frame, the existing
hardware may prove handy as part of a nifty hinge or a ready-made handle.
Tempered glass doors come in all sorts of weird sizes, so it’s best to
secure a top first, and then tailor the frame to match its dimensions.

Use thick blankets, quilts or bedspreads to bring winter-sown frames
through winter storms, or to block sun when you can’t be around to vent
the frames. Snow makes a good insulating cover, too.
--------------------

paul tradingpost@lobo.net







  • [Livingontheland] Use Cold Frames to Grow More Food, TradingPostPaul, 11/24/2007

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