William McKay bmckay55 at
Sun Sep 24 08:45:27 EDT 2000

A couple of thoughts regarding greenhouses.  If you are going to build one 
and heat it, you probably want one at least fifty feet long.  You can get 
them 17x50.  If it turns out that initially you do not need that much space 
(but you think you will in the future) you could block off part of the house 
in the winter with plastic to reduce heating costs.

An alternative is to build your own unheated house.  I have one which is 
extremely useful to (1) extend the season three or four weeks on each end 
and (2) provide space for transplants to grow on.  The transplants can not 
be started in the unheated greenhouse, of course;  I start mine under lights 
in the basement, get them large enough to transplant and then move them to 
the unheated house.  Here in Eastern Massachusetts I can put tomato 
transplants out at the last week of April & hardier stuff even earlier.  In 
fact, I have wintered over lettuce & other cold hardy plants even with 
temperatures of -5.

You can build your own with pvc pipe (1 or 1 1/2 inch), regular greenhouse 
plastic & plenty of ventilation on the end walls.  Even buying everything 
new, you could build a 12x24 house for three or four hundred dollars.  The 
trick with these is to keep the length no more than two or two and a half 
times the width so they will self ventilate.  No matter what you do, even 
rolling up the sides, they become pretty hot by the end of May.  Elliot 
Coleman has a couple of useful examples in his books, especially Four Season 
Gardening.  Somewhere I have a description of how I built mine and could dig 
it out and send it.

The upside of one of these unheated houses is (1) they are cheap & reliable 
(2) you can extend the season two months (3) if you do greens, you can have 
marketable produce by the beginning of April (here in Mass) and you can have 
good produce through the middle of December or even later.  Baby salad 
greens will last even longer.

The downside is that, especially in the spring, you are somewhat at the 
mercy of the weather.  For example, this spring was consistently cloudy & 
very cool.  My tomatoes took another week or so than normal to mature and I 
had to be very careful with fungal disease problems.  Nevertheless, in a 
very small house I managed to grow out 800 or so tomato plants, lots of 
lettuce, broccoli, kale, squash, etc.

Bill McKay

The advantage of

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