Winter Harvest in a Summer Greenhouse

June 20, 2015

Despite having some serious garden space devoted to hoophouses, we use them mostly for season extension, and reliable ripening of some warm weather crops.  But we let them rest during the winter months with the covers off.  Sort of like Eliot Coleman’s movable hoophouses, except we don’t move them, we just expose the soil and cover crops planted inside to real weather for the winter months.

In our maritime climate we usually (usually) can harvest hardy greens and some cabbages all the way through winter.  But last year November was about like this, and bam, we were down to the temperatures in the teens overnight.  My dahlia bulbs froze in the ground, that was how cold it was.  Some plants survived, but only survived as mushy looking stumps.  All our winter cabbage was turned to mush, and even the kale looked like someone took a blow torch to it.  The kale survived but there were no leaves left to harvest, just woody stalks that would hold over until spring.  Just like that we were out of greens, when normally we can harvest greens of some kind all the way through winter.  But… .

Sometimes I’m a little slow on the uptake or just plain lazy…we have two small hoophouses that we built for chicken brooding when we were selling pastured poultry.  We offered eggs, broilers and turkeys.  A hoophouse seemed like the perfect brooding setup for us, natural light and warmth, inexpensive, and away from any of our wooden buildings in case of fire.  And in the case of PPBO (pastured poultry burn out) we still had a some nifty hoophouses.

The chicken brooder hoophouses are shown to the left. They each measure 20′ x 20′.

We don’t sell poultry products anymore but we still use the hoophouses for chickens.  One to raise the babies in, and one for the laying hens.  Rather than do the whole pastured poultry thing with a small flock and not liking the fixed dirt yard for hens, we deep bed them year round and have turned them into our garden compost makers.  But that is fodder for another post.

That freeze last year really kicked me into gear.  Rather than just leaving the brooder empty all winter, why not grow in it again.  We have used it many times as a prop house early in the season, just because sometimes we don’t have the covers on the large hoophouses, and the 20′ x 20′ hoophouse really heats up with just a few hours of sun and provides the natural light the plants need.

So this year when we rotated out the old flock and moved the young pullets, we stripped the brooder of its deep bedding and watered the crap out of it.  You have no idea how dry soil in a hoophouse can get without irrigation.  Since chickens like to be dry, this hoophouse hasn’t seen water of any kind since we replaced the cover in 2009 after the 2008 snowstorm that wreaked havoc here on the greenhouses 😦  For a less sunny view of the greenhouses read here.

The next task ahead of us was breaking up the soil that had been compacted for a couple of months each year by twenty to fifty chicks.  Chickens are hard on the ground.  We don’t have a walk behind tiller so it was pure shovel work.  We weren’t so concerned about breaking up all the ground, just enough space for planting some winter greens.  We were planting transplants instead of direct seeding so it could be pretty rough.  A shovel and a little hoeing and raking worked just fine.

One concern we have with winter growing/harvesting is that our hoophouses are oriented north/south because we want the most light during the growing season.  But during the winter, the end walls cast some shade which is a fine trade-off to me for our needs.   But we have to take that into consideration when we plant.  So to that end, we only shaped beds on the northern most two-thirds of the hoophouse.

We planted in September which is a little late, you want your plants to be mature enough to harvest, but not too mature or they may succumb to freezing, and on the other hand you don’t want them to be too small because they will just stop growing until the days lengthen in the spring.  Each year is different too, what works one year may not the next.

Volunteer tomatoes November 6, 2015 If you think poultry will eat weed seeds out of compost, these tomatoes tell a different story.

While the hoophouse is warm enough to sprout and grow tomatoes in fall, the cloudy day and nighttime temperature only runs about one or two degrees warmer than outside.  Ventilation is the hardest part this time of year for the plants.  Low light, cool, and moist conditions make plant selection a little tricky.  We went with a pretty simple selection of greens to see how they would go into fall and possibly overwinter.  The lettuce is already done, tatsoi isn’t too far behind, while Tokyo Bekana and Joi Choi look promising for a while longer.  The workhorse of this planting is the kale, and we added a new leaf broccoli, Spigariello to see how it performs.  It’s pretty hard to beat kale in the maritime northwest for a hardy green, though.

If I made any mistake here with the plantings, it’s spacing.  Air circulation is a must with winter crops.  So I’ve been steadily harvesting the lower leaves of each planting to improve the movement of air between the plants.  It’s been quite some time since I planted  in the fall in the hoophouse, mostly relying on what was in the garden to tide us over, or not.  To really compare garden versus hoophouse we planted some of these crops outside and some in.  What I see now in hindsight, is that I wasted my time planting lettuce in here, our garden lettuce did much better in the fall, without the huge temperature swings.  A few 90F degree days in September really bothered the lettuce in the hoophouse due to the fact that 90F degrees outside is 90F degrees, and inside the hoophouse even with the door open and a north/south orientation it can easily reach 100F degrees.  I would have been better off using the space for more hardy greens, but that’s why gardeners experiment right?