Over-Wintering Greens in our new Hoop House
Here in Northern Vermont the average grower has to wait until mid-to-late May to direct seed their spinach, with a harvest that will be anywhere from 3-5 weeks later – pretty close to mid-to-late June. Who wants to wait that long for fresh spinach? We know that we don’t, so last fall we joined a growing number of northern farmers who are experimenting with over-wintering greens for earlier harvests.
Why didn’t we just use low tunnels instead of a big hoop house? Low tunnels have their advantages in that they are moveable, cheaper, and more flexible, but we were looking for an option that wouldn’t require us to shovel snow out of the way to harvest our crops, had more space for growing other crops such as tomatoes and cucumbers in the summer, and was able to retain heat more effectively.
Last summer we built a hoop house (22’ x 96’ high) – basically an unheated greenhouse. On September 15th we direct seeded almost 70 varieties of greens (primarily spinach, baby leaf lettuce and brassicas) for trialing purposes in the hoop house and covered the rows with two layers of row-cover over wire hoops. Our trial goals were to determine:
- Winter survival
- Freeze damage
- Winter growth
- Rate of spring re-growth
- Disease resistance
- Color (extra cold, low light, indoors, shorter day – can lead to pale & washed out varieties)
- Timing of planting
- Overall Quality
In the future we will add the issue of timing to our trials goals – we’d like to determine what the best time is to direct seed or transplant different crops. At what size can plants survive the winter better? Bigger plants have more surface area that is exposed to the frost, while if the plants are too small they aren’t able to benefit from being planted so early.
With many feet of snow piled up against the edges of the hoop house, we were able to harvest our spinach four times – Dec, Jan, Feb, and March. Tony Ingraldi, our trials crew harvest manager, expects to be harvesting spinach every 1 1/2 to two weeks from now through at least mid-May. "The spinach has been incredibly sweet and the re-growths have been very high quality" Tony said. "We've been really excited by the yields - roughly 3 lbs of spinach per 3' x 6' row - definitely enough to feed a family or, on the scale of our 22 x 96 high tunnel, offer some tasty, early greens at market."
Since we haven’t finished our harvesting we are holding off on any recommended varieties, but look for that information in the near future after we finish our trials, and for even more conclusive results after next winter’s trials.
For the northern market grower, having a hoop house is a huge boost in establishing a year-round business. In this area, the market value for fresh organic winter spinach was $8-12 lb, or $6-10 wholesale. With a hoop house the size of ours, a grower could easily surpass 100lbs of spinach over the winter.
Also, early market growers have an advantage over other growers – by offering vegetables early in the season, a habit is established with customers and chefs that they are a reliable source for fresh vegetables. Producing high quality organic spinach in the winter shows the community that we can keep it going all year round!
Mother Earth News published a comprehensive article in 2003 called Low cost, versatile Hoop Houses!
Where did we get our hoop house kit?
Several people have asked where we bought our kit - we went through Ledgewood Farm, noting that these hoop houses can withstand snow well for a few hours without collapsing.