Late Winter Garden Update

Two fullsized ice chests stacked on one another in 20" of snow.
-February 9, 2011

Wet January and February
-March 1, 2011

After a dry and mild November and December, we've had a wet and wild January and February, including a near record 20" snowfall and wide temperature swings from -18 degrees up into the low 70's.

A day after the snowfall, we experienced -18 degree temperatures.  Northwest Arkansas is in zone 7, but we got temperatures down into zone 5!  Fortunately, the 20" of snow was on the ground and provided some insulation.  We'll wait and see what damage was done to our perennials by the extreme cold snap.

Scotch kale growing in a cold frame

Swiss chard growing in a cold frame

Despite the extreme low temperatures, the Scotch kale and Swiss chard are flourishing in the straw bale cold frame.  I am very impressed.

Daughter strawberry plants in need of transplanting

The uncovered strawberry plants suffered some freeze damage, but again the heavy snow cover insulated them through the worst of it.  They are putting on new growth and are in need of transplanting into the blocks.

Evergreen bunching onions putting on new growth

With the recent warm weather, the green onions have exploded.  Onions being a biennial plant, they should put on seed in this second year.  We will wait and see how the seed production affects edibility.

Chickens newly feathered and laying eggs again

Eggs!

During the heavy snow, the chickens mostly stayed in their house, because they couldn't get around in it.  They didn't seem to be affected by the cold much as long as they had a draft free house to huddle in.  Since coming out of their molt, the hen's egg production continues to fluctuate between 0-6 eggs per day with an average of around 3 eggs a day.  Hopefully as the days grow longer, they will pick back up to 5-6 eggs a day.

Daffodils emerging

One of the traditional signs of early spring, the daffodils are starting to come up.  With almost two full months left before our average last frost date in late April, this is concerning.  The early warm spell will cause a lot of early flowering crops (peaches, strawberries, etc.) to get going early and their blooms are likely be nipped by frost.  Could make for some light early fruit harvests this year.

Cold Frames Revisited

In case you missed them, find our previous posts about cold frames here and here.

Swiss chard growing in January

The straw bale cold frame has performed remarkably well.  With no supplemental heating, it has sustained the cold tolerant Swiss chard and the cold hardy Scotch kale quite well through overnight temperatures down to 5 degrees.  The cold intolerant sweet basil did not make it when temperatures got into the teens.  The thick bales provide a remarkable level of insulation.  The key is to grow cold tolerant crops and when the temperature is above 30-32 degrees, remove or prop open the cover to allow more sunlight in and more importantly, to not overheat the plants inside.  When temperatures are going to be lower than 30-32 degrees, cover them over for protection.  Simple.

Shadow cast by the southern wall of the cold frame

During the short days of winter, the sun sits very low in the southern horizon.  This creates a significant shadow effect from the southern straw bales as seen in the picture above.  The crops inside need as much solar exposure as they can get this time of year if they are going to not only survive, but produce a harvest of greens for you.  So this shadow was a real problem.  I thought and thought about what to do, thinking about translucent materials for the south wall such as a greenhouse panel or glass blocks.  Both of these were too expensive.

Straw bales on the southern side rolled down and away

So, I am standing there looking at the cold frame and had a Eureka! moment.  Why not just roll the two southern bales away on sunny days (as seen above) and replace them when it gets cold.  This allows full sunshine into the cold frame with no additional cost and minimal effort.  It has really worked out well.

Lettuce with freeze damage when covered by a 1 gallon glass jar

Lettuce with freeze damage when covered by a 10 gallon aquarium

The upturned glass aquarium and jars worked within their performance envelope, but didn't have nearly the insulating properties of the straw bale cold frame.  They seemed to protect the lettuce down to 25 degrees or so, but even then any lettuce that physically touched the glass at this temperature was ruined as seen above.

Have you been using a cold frame?  I'd love to hear your experiences and suggestions in the comment section below.

Building and Using a Cold Frame (Plus Some Alternatives)

See previous post about cold frames here.

Six bales of straw make up the walls of this cold frame

 We helped a customer construct a simple, straw bale cold frame a few weeks ago.  As seen above, an enclosure is made around the bed with the bales.  We pushed them together tightly and stuffed straw into any cracks to prevent drafts.  For the top, they covered two old screens from a sliding glass door with plastic.

Sliding screen doors covered with plastic serve as a cover

When an overnight freeze is expected, the tops are put in place a few hours before sundown to gather the sun's warmth.  In the picture above, only one screen is in place.  A second identical plastic covered screen will completely seal off the interior of the cold frame.  Swiss chard is visible growing in the lower right quadrant.

Young kale growing in the cold frame

Kale is quite cold hardy and with this cold frame in place, they should be able to grow it all winter long.  The green grass on the left are sprouts from wheat seed left in the straw bales.

Sweet basil growing next to kale

 Even after getting down to 22 degrees, this volunteer sweet basil plant is doing just fine.  Basil is notoriously intolerant of freezing temperatures, so it is a good sign that the cold frame has been effective.

How to use a cold frame:


Cold frames are not a "set it and forget it" tool.  They require the gardener to monitor the forecasted temperatures and the conditions of the plants inside.  If the temperature during the day is in the mid 60s, the temperature inside could easily climb into the 90s or higher, roasting the plants inside.  If it gets too hot inside, lettuces and other greens will think it's summer time and will bolt (send up flower stalks), which makes them bitter and inedible.  Control the temperature inside by propping open the top or removing it all together on warm days and sealing it up tightly on cold nights.

Don't let me discourage you though.  This time of year, the top stays off most most nights.  As an example, looking at the forecast ahead, our customers won't need to cover their cold frame again until Saturday night.  Today is Monday, so that's a pretty good stretch without having to do anything.  Early in the season, the cold frame is there to get you through the cold snaps here and there and allow your garden to enjoy the great growing weather in between.

Jugs of water inside the cold frame will absorb heat during the day and radiate it back out at night.  This can help keep the cold frame warm as we get farther into fall and winter.  When temperatures dip into the teens and lower, a heat source may be needed at night.  A 100 watt light bulb is simple and effective.  A small, electric heater with a thermostat can also be used.  Please exercise all due caution with electrical devices.

Here's a previous post on cold frames with more information.

Alternative uses of household items:

A cracked aquarium makes a great miniature greenhouse

The lettuce in the aquarium above had been harvested for last night's dinner.  Note that the plants were cut 1-2" off of the ground.  This allows it to regrow again and again without requiring replanting.

A fish bowl, a one gallon pickle jar, and a juice bottle with the bottom cut out

Many things around the house can be used to keep the cold out.  Ask around for old, unused fish aquariums.  If you cannot find any, Wal-Mart typically has small fish aquariums at a low cost and a few of those can keep fresh salads on your table well into the winter.  Treat these like cold frames and remove them on warm days.  Put them in place a few hours before dark when a freeze is expected.

An unused fish bowl keeps the cold at bay for this lettuce

Note the increased growth of the previously covered lettuce

Random thoughts:

• The straw bales will absorb water and begin to break down over the winter.  They should make a nice addition to the compost pile in the spring.
• I am contemplating replacing the straw bales on the south side with some transparent material to allow more sun into the cold frame.  As winter progresses and the sun sinks lower into the southern horizon, that southern wall will cast a longer and longer shadow into the growing area.  Perhaps a sheet of transparent corrugated siding used in green houses?
• Remember that with the top in place, rain fall is excluded.  Water as neccesary.
• The artificially warm environment can attract/house damaging insects, voles, and mice.  Keep an eye out.

UPDATE:  See updated results and experiences with cold frames and glass enclosures here.

Workshop Notes: Extending Home Vegetable Production Beyond Summer

We attended a workshop last weekend to learn more about fall/winter gardening.  It was put on by the Fayetteville Community Garden Coalition, in conjunction with Ozark Alternatives and The Blackberry Farm Community Garden.

Here are some highlights:

Cold Frames:


Cold frames are semipermanent enclosures that trap solar energy during the day and retain it at night as outside temperatures drop.  This allows the gardening season to be extended late into the fall and begin earlier in the Spring.  On frosty nights, a few hours before sundown, close them allowing heat to become trapped inside.  On very cold days, they can stay closed all day long.  On warm, sunny days the temperature inside can rise too too high.  On these days, open the cold frame to allow the heat to escape.

Straw bale and glass door cold frame

A simple, cheap, and effective cold frame can be built from a recycled glass door, six bales of straw, and a stick.  Simply form a rectangle around the bed with bales of straw to serve as insulated walls of the cold frame.  Elevate the bales on the north side of the frame about 18" to achieve a 35 degree slant towards the south.  Place the glass door on top of the bales of straw to form a transparent roof.  The weight of the door will hold it in place.  The stick is used to prop the roof of the cold frame open when necessary.  During expected freezes, stuff straw into any cracks to seal out cold.  The bales absorb moisture and will decompose over time requiring replacement.  On the bright side, they provide the backyard gardener with a source of compostable material.  Do not use hay in place of straw.  Hay generally contains a lot of weed seeds and you will spend several years battling them.

Total cost of door (free) + straw ($4 a bale) + stick (free) = about $25.00

Wire and plastic cold frame

This cold frame design is built from 2x8" boards, concrete reinforcing wire, and greenhouse grade sheet plastic.  Simply cut one board in half, forming the 4' long ends.  Screw the boards together to form a 4'x8' box.  Make a arching roof out of the wire, making sure that the maximum height of the roof is no more than 2' tall.  Remove any sharp edges on the wire that could snag the plastic sheeting.  Cut two sheets of plastic wide enough to cover about 2/3 of the roof as measured from the ground.  Cut these sheets long enough to leave 4' of plastic on each end.  Tack the long edge of a sheet to the board on one of the long sides of the cold frame.  Repeat this with the other sheet on the other side.  Cut three strips of plastic 2' wide and long enough to go all the way over the arch of the roof.  Leave enough extra length on the ends to provide for tacking it down.  These strips are folded twice lengthwise to give a three sheet thick, 8" strip.  Put these strips over the larger plastic sheets at each end and the middle of the cold frame and tack it down tightly at both ends.  The larger plastic sheets can now be adjusted as needed.

Total cost of three 2"x8"x8' boards ($15) + wire ($15) + plastic ($10) = $40.00

Low tunnel covered with thin, perforated plastic

Framework for a low tunnel

A temporary low tunnel can be built over rows (or beds) to provide frost protection.  It is not well suited to small, backyard gardens because it is somewhat labor intensive to cover a small stretch.  If you have 100' rows to cover, it would be a good option.

Every 4-5' on each side, pound 2' long pieces of reinforcement bar into the soil at an inward angle.  Make a cross support for the tunnel by placing a piece of flexible underground piping over the reinforcement bar.  Stretch the perforated plastic over the framework and secure it by weighting the edges down with 5' pieces of 1/2" reinforcement bar.  The speaker emphasized using 1/2" instead of 3/8" because the increase in weight really helps hold the plastic down in a wind.

Cut up an old piece of garden hose into 3" sections and split them on one side.  Put two of these on each support bar over the plastic and hold them in place with a piece of baling or electric fence wire poked through the plastic.

Cost depends on length of rows.

Tips and Tricks:

• A cold frame should never be higher than 2 feet tall inside or any heat trapped will rise too high to be of any use in warming the plants and soil
• In the northern hemisphere during the winter, the sun travels low in the sky to the south.  When building your cold frame, angle the transparent roof (if possible) to be perpendicular to the sun.  In Northwest Arkansas, the winter sun's angle is about 55 degrees, so build the cold frame such that the roof is tilted towards the south at about 35 degrees when closed.
• Any foliage physically touching the cold frame's exterior plastic or glass during a freeze will turn black and die.
• Wet the soil just before a frost/freeze.  Hydrated plants handle it better and the moisture helps conduct warmth from the subsoil.
• Place dark colored jugs that are filled with water into the cold frame.  They will absorb heat during the day and radiate it back out during the night.  This can make a difference of a few degrees.
• On cold windy nights where it gets into the mid 20's, throw an old blanket over your cold frames to provide extra insulation.
• On nights where it gets into the low 20's or colder, a supplemental heat source will be needed if you wish to continue gardening.  A 100 watt incandescent light bulb, a can of Sterno, or even an electric heater can be used.  Use all caution where fire and electricity are involved.

Vole Trap:

Vole trap

Entrance to the vole trap

Have you ever had a pepper plant wither and die for no apparent reason?  A fruit tree not leaf out in the Spring when it had looked fine going into the fall?  You may have a vole problem.  These small, mouse-like creatures love to eat the roots of pepper plants (and other plants) and during the winter, they will even eat roots and the bark from trees.  One of the speakers showed us this simple, nontoxic vole trap that he claims is very effective.

Construct a wooden box about the size of a shoe box with a removable top.  Cut a small (~1 inch) hole in the side at the very bottom.  Put the box in your garden with a snap-type mouse trap inside.  Bait it with small pieces of cut sweet potato.  That's it.  Pretty simple.  The voles like warm, dry environments like the wooden box and the box will keep your children or dogs from getting caught in the snap trap.

Various Other Notes:

• Green beans will grow in soil that is too cold for it to germinate in.  So, in early Spring, start them inside and plant outdoors after the last killing frost.  A good time to put them into the garden for Northwest Arkansas would be the middle of April.  This will gain us almost a full month of growing season.
• Asparagus, with its 15' deep root system, can withstand high levels of salt once it is established.  Because of this, salt can be used as a weed inhibitor in your asparagus beds.