Tuesday, November 20, 2012

It's winter. Time to think about spring

The Winter Harvest Handbook, by Eliot Coleman
I'm always interested in ideas, and things that involve compost really interest me as I've got a lot of compost, and one of the things that "got" me was the concept of growing things in an unheated greenhouse.

This book talks about growing winter-hardy vegetables in an unheated greenhouse in Maine, which is considerably colder than Western Washington in the winter, and it covers a variety of topics.

I think this book is aimed at people who want to have market gardens or to increase their utilitization of their land during non-typical seasons.  The basic technique espoused is to have a hoophouse which provides some cover, and an inner crop-cover, which provides further protection. 

The author describes situations where the outside temperature is very low -- 10 degrees F or -12c, where the inside temperature at soil level is in the low 40s or high 30s.  That's enough protection that cold-hardy vegetables will not be affected, and allows cropping of fresh vegetables during winter. 

What is of particular value, if you're considering doing this for a market-garden application, is the discussion of planting schedules and seccession planting.  You plant the winter vegetables in the late summer or early fall, in waves.  The maturation is slower than it would be in summer, but the spoilage is, too.  So your salad greens have a longer harvest period. 

He talks about moveable greenhouses, mounted on skids, on specific types of vegetables that grow and sell well, and has useful notes on marketing vegetables and establishing a brand that consumers can follow. 

In my temperate marine climate, where the average high temperature in January is 47 degrees F or 8 degrees C and the low is 36 degrees, or 2C, I'm curious what temperatures I could achieve in an unheated greenhouse.  47 degrees is only 20 degrees from tomato temperature.  Hmmm... 

The compost that I produce throws off a lot of heat as it converts.  I wonder if I couldn't get to tomato temperatures by using a hoophouse on a few feet of compost. 

There are tables and planting schedules for their farm, as well as the general layout and the size of various fields and structures.  It also has pictures of the packaging and talks a bit about what sells and what doesn't.  That sort of information is hard to come by.   

Finally the book talks about tools and jigs to make planting easier, and I found that discussion to be pretty useful.

For anyone considering building a hoophouse I'd say this is a useful book, and it certainly has made my seed-catalog perusing more interesting. 

1 comment:

Joanne said...

I've got Elliot's book and this is how I've been growing produce through the winter for a couple of years. I don't grow in a big hoophouse (I haven't had one, but I'll be building two over the winter or in the spring).

I grow produce in low tunnels built from schedule 40 pvc with steel T-posts at each end of the tunnels to stabilize them. I'm currently in Mulino, about 20 or so miles from Portland, Oregon. I grow a lot of leafy greens in the tunnels - leaf lettuce, endive, mustards, cilantro, etc. as well as garlic for green garlic (I normally don't grow it for the heads), leaf celery, etc.

They work very well in my area and should work well in yours, especially if you do something like what you're talking about.

Will Allen, of Growing Power in Milwaukie, Wisconsin also grows greens in greenhouses and hoop houses. He uses compost to heat some of his greenhouses. He does a lot of container gardening to use the vertical space inside the greenhouses as well as the floor space.

I grow a lot of my leafy greens in 72 count plug trays and those would do very well on a deep bed of wood chips. The issues I've found with slow growth on the leafy greens has more to do with cooler air temps than short day length, so if you could place the trays on a layer of wood chips that are warm, that would shorten your turn around on crops.

The one thing I've noticed with my low tunnels is that you have to keep an eye on the outdoor air temps when the sun's out. If it's 55 and sunny outside, I have to open up the ends of the tunnels or it'll cook my plants, especially when they're hardened off to cooler temps. But that's easy enough to do.

My farm's The Little Homestead and I posted a video a couple of years ago about how I use low tunnels to grow crops over on Youtube. I can post a link if you like.