Lettuce growing in my cold frame.

When I built my 50 dollar greenhouse over a year ago one of my goals was to be able to have something fresh to eat out of the garden or greenhouse every day of the year.  Well, it’s been about a year now, and  it hasn’t even been very hard to do.

Here is what I’ve learned so far -

Despite what you might have read, lettuce spinach and other salad greens are not really  particularly quick crops.  Sure you can have a pretty little stand of plants in about 6 weeks or so under good conditions, but  in cool weather  they don’t really get productive until they are  almost 3 months old.  Yes you can harvest a few salads out of the thinnings, but the young plants  aren’t going to yield an every day supply unless you can plant a pretty large area.

When it gets cold, growth slows way down.  However, on sunny days the temperature under glass (or plastic) is balmy, and I’ve continued to see steady growth all winter long.  What should be done in the fall is to have a lot of greens grown out as much as possible before it turns so cold that growth slows down.

It’s quite difficult to get those cool season crops to grow productively in Tennessee until late into our rather warm autumns, but once it gets to be jacket weather they do great.  Same thing in the spring – once the nights get warm they fail or go to seed.  So the easy thing to do is to seed dirrectly into a cold frame or green house in September, then seed again every few weeks all winter long and you can have fresh lettuce and spinach from  before Thanksgiving until June.  Last year I had tons of productive growth by late winter/early spring.

You can not only grow, but garden in relative comfort all winter long in a simple greenhouse like my $50 hoop house.

These crops are almost completely freeze proof – especially spinach.  I’ve had temperatures down to 5 degrees with only minor damage to lettuce and none to spinach inside of a frost encrusted cold frame, and even less damage inside of the hoop house for some reason.  It’s easier to keep them growing in cold weather than to keep them from bolting (the elongation associated with going to seed which triggers instant bitterness) in early summer.

One of the beautiful things about cool weather gardening is the absence of insect and weed problems.  There are usually a few of both, but not to the point of being a problem.  Also having productive plants growing in January is really therapeutic to a gardener with cabin fever.

This picture was taken on Nov. 5 - with a little bit of effort (and a cold frame) your garden can be productive almost year around.

I’ve only mentioned cool weather plants in this post, but it’s worth mentioning that in my area most gardens go to the weeds by early August when they don’t have to.  If you want to have a 4 season harvest you have to plan and plant in all 4 seasons as well.  I’ve found that the late summer – early fall is probably the most challenging time because it is hot and dry, and insect pests are at their peak, and it just isn’t very much fun.  Nonetheless with just a little timely effort you can keep your garden productive by planting the right thing at the right time and also yanking out old plants once they stop being productive.

This plastic tunnel is being used inside of the greenhouse to protect tender plants against a late hard freeze - very effectively I might add.

A simple plastic tunnel like this can serve as a cold frame to grow salad greens  all winter long, to grow out tomatoes and other tender plants, to extend the season for an early Spring start or a late Fall harvest, or even as a screen house to keep birds off of your strawberries or vine borer moths off of your squashes.  You can also use one of these to dry out water logged beds and warm up the soil so that you can begin planting  in early Spring. These devices are so useful, cheap, easy, and quick to build that everyone should have at least one – it’s almost as good as having your own polytunnel greenhouse.

materials for plastic tunnel row cover

Materials:

• 5-5′ lengths of 3/4″ (inside diameter) polyethylene water pipe
• 10 – 1/2″ x 1/2″ x 14″ wooden stakes
• 1 – 12′ x 6′ x 4 mil clear plastic sheet
• 4 – 1/2″ x 1 1/2″ x 8′ wood strips
• staples and nails.

As usual you can (and should) substitute materials that you have available on hand.  You can use anything for stakes that are strong enough to drive into the ground and will slip inside of the rib pipes. You can use a broom stick, piece of pipe or any long thin objects for the poles, and you can fasten the plastic skin to the poles with duct tape instead of staples.  Clearly almost any kind of bendable pipe can be used for the ribs, but here’s a tip – contractors or plumbers are likely to have a scrap collection of one kind of plastic pipe or another that comes in coils that they will either give away or sell incredibly cheap – just ask.  In the worst case, you can usually buy cut lengths at the home improvement or hardware store.

This design is also great for hardening off. The cover can be opened or closed in about a minute by one person. The whole thing can be moved to a new location and set up in 15 minutes.

Start by cutting your parts to size – this tunnel will cover an area that is from about 2 – 3  feet wide and the black pipe for the ribs are 5′ long, and the plastic is about a foot and a half wider – you can roll up any excess plastic on the poles so it is better for it to be too wide than too narrow.  In this case I made the poles shorter than the plastic so that the excess could be used to close up the ends, but you could also make the poles the same length as the plastic and use rectangles of plywood or other sheet lumber to close up the ends.  Use your imagination.

Once you have your parts cut to size fasten the poles to each long edge of the plastic sheet.  I used staples to do this, and then rolled the plastic around one piece of wood and fastened another strip to it so that the plastic is sandwiched between the wood pieces.  If you are just using tape, then you will want to wrap the plastic around the pole and tape the plastic sheet back to itself forming a tube with the pole inside – tip: construction tape (duct or housewrap tape) sticks very well to plastic, and not very well to wood – don’t try to tape to the wood other than as a temporary measure.

Once you have that done, roll the plastic up around one of the staves until you are ready to deploy it.

The ribs just slip over the stakes - you can probably get by with ribs that are much further apart than this if you want.

In the garden, simply drive the stakes into the ground where you want them, and slip the pipes for the ribs over them.  Since my ribs are made out of coiled pipe they already have the right shape, if you used straight sections of pipe you might need to use something more robust than 1/2″ wooden stakes to hold against the tension of the polytunnel ribs.

Now just roll your plastic out over the ribs and there you have it.  If you experience a lot of wind you might need to weight down the plastic a bit, but under normal conditions the wooden pole will probably do the trick.  When you need to get into the pollytunnel you just lift a pole and lay it over the top – almost as easy as a regular cold frame, but a lot easier to build or move.

Now would be a good time to build one!

Mid November brings the first hard freeze - and frost painting on the cold frame.

I took this picture on our coldest morning so far with over night lows in the upper teens. Yet according to my tell tale thermometer the temperature in my small green house has never dipped below 32 degrees F – although I’m sure it soon will.

This garden is full of fresh greens in late November.

I spotted this thriving fall garden in a vacant lot as I was driving through the edge of town. It looked so good to me that I stopped to talk to the gardener – Jack, a retired mason – who was out enjoying the brisk sunny weather and picking himself a “mess” of greens. Everyone in the south says that – a mess of greens.

Anyway I asked him if he had any secrets to his beautiful fall garden. “No, just plant in September, and water it good.” I was a little bit surprised, because this past September was hot as blazes here in middle TN, and all of his crops – turnips, collards, cabbage, broccoli, and cauliflower – are certainly cool season crops.

I don’t know if Jack is actually going to get much cabbage, broccoli, or cauliflower before it gets too cold because those were just beginning to form heads – I think I’ll check back later and see. However it all looks great despite the fact that our temps have already dipped into the teens, and he’s already getting loads of fresh greens from the other crops. I’m certainly going to plant some of this stuff next year.

A cold frame can extend the growing season by weeks at both ends.

The lettuce, spinach, and radishes growing in my cold frame are coming along nicely, although I wish that I had planted some a few weeks earlier as well. Even though the over night lows in the cold frame are right at the freezing point, the daytime temps are in the seventies and I can still see steady growth at this point. Until the nights got cold I had a plague of volunteer tomato plants coming up in here!

I'm starting these lettuce plants under fluorescent lights.

I’m hedging my bets for winter salads by starting some lettuce under lights. Once they get big enough I’ll move some into a window box (with supplementary artificial light) and some into the greenhouse or cold frame. As you can see these were started on Nov 16 and came up 3 days later – about a week ago.

Set your artificial lights as close to your plants as possible.

If you want to grow under lights you can use plain old 4 foot shop lights with 40 watt soft white bulbs – you should be able to get two double bulb fixtures and a timer for well under 30 dollars – maybe even under 20 dollars of you look around. Don’t even worry about special “grow” light bulbs or fixtures unless you are planning to grow to maturity warm season crops like tomatoes or marijuana – in which case you need more advice, like from an attorney

You must use a timer to have any success. Plants “know” what time of year it is by the day length, and if you don’t use a timer the irregular hours of light and dark will freak them out, and might make some plants try to bolt – go to seed – almost immediately.

If you can, put your plants and lights in a window to take advantage of whatever light is available naturally. Set your timer for about 10 hours of light which coincide with actual day light hours. Since fluorescent light is a pale comparison to sunlight you should set your lights as close to the top of your plants as you can – even closer than in this picture.

Fluorescent light bulbs don’t get hot (although the ballast might) so it won’t hurt your plants even if the leaves touch the bulb, but old style incandescent light bulbs do get hot enough to burn the plants if they get too close.

Our plant room is usually really crowded this time of year

We don’t have enough room or enough sunlight in our house for all of the tender potted plants that we have – so a couple of years ago we built a plant room to overwinter them in.  Our plant room is just a small well insulated room with 4 recycled windows built onto the side of our garage. The natural light is supplemented with some fluorescent shop lights. On a sunny winter day the temperature can increase by over 20 degrees just from the sun, and the 5 barrels of water that you can see sticking out in the lower right store the heat and release it at night thus keeping the temperature moderate in all but the coldest weather. When it gets really cold a small electric “freeze guard” heater keeps the temp above 50 F. We can over winter just about anything in here, and it’s also a great place to start seeds to move into the garden later. A few minutes in here can really lift the spirits on a cold winter day. I do need to sweep that floor though.

It’s almost winter, but you can still enjoy growing something if you set your mind to it.