Vinnie Bevivino
vinnie@seedandcycle.com

Seed and Cycle

Winter Time Growing in Hoop Houses

Winter Time Growing in Hoop Houses

The key to effectively utilizing hoop houses throughout the winter is keeping them as airtight as possible, and then managing your moisture to allow for your plants to thrive.

This article obviously doesn’t cover everything to know about creating hospitable environments for your crop.  There are amazing farmers having success with using geothermal, solar hot water, and compost as heating sources.  This article concentrates on what you can do today, with little effort, for less than $20.

Reducing drafts, increasing inside temperature:

Any small draft will push in cool air and reduce the overall effectiveness of the hoop house.  Here are a few ideas for keeping your hoop house airtight and temperate for optimal growing in cold weather:

1) Start by sealing up the space around your door on your end wall.  To fill any gaps, consider using one of the following:
-expanding foam, an aerosol product available in hardware stores, or
-used bike tubes, cut open and stapled on the wood on the inside of the hoop house.

2) Cold wind will slip in around the edges of your door.  Line the inside edge of your door frame with either quarter-round molding or a 2×2 piece of wood to prevent wind from entering from this small space.

3) Understand where prevailing winds are coming from.  During the coldest months, put an additional piece of plastic on the inside of your end wall that receives the most wind.  This will reduce drafts, but make that doorway unusable for the time being.  If this is too inconvenient, cut plastic in strips so you can still walk through, similar to walk-in refrigerators.

4) You may want to consider adding a second layer of plastic over the entire hoop house to reduce the amount of heat loss.  This is best accompanied with a small fan available from greenhouse supply companies used to blow air and inflate the space between the two pieces of plastic.  Simply attach a second piece of plastic over the first from hip board to hip board.  It is unnecessary to have double layered roll-up sides, as most of the heat is lost through the top.

5) It is a good idea to further protect your plants with low row tunnels. Use wire to create small hoops over your crops every four feet and drape breathable row cover over.  Use clothes pins to keep the row cover from touching the plants below.  This will prevent the row cover from freezing to your crops and causing frost damage to the leaves.

6) Another source of drafts are your the ends of your roll-up sides, at the four corners of your hoop house.  During the colds months, when you don’t need to vent your hoop house, you can seal these corners by installing wiggle wire tracking to the side wall face of your first and last hoops from below your hip board to above your base board.  Roll down your side and seal the corners using wiggle wire.  You won’t be able to roll-up your sides, but that’s okay during the worst of winter weather.

Managing internal moisture:

The other problem growers run into is managing moisture during the winter months.  When growing in an airtight hoop house, moisture builds up and can rot your crops.  There are three things you can do to prevent this:

1) Start by watering much mess frequently than during the rest of the year.  Water is used by plants for two reasons.  The first is used to create sugar (energy) via photosynthesis.  Second, it is used to regulate temperature, much like how we sweat.  Both of these uses are drastically reduced in the winter as plants are not trying to cool off, and the shorter days are reducing photosynthesis.  Therefore, water much less then you regularly do.  This may mean weekly watering, this it may mean even less.  Remember, you shouldn’t be starting new seeds in the dead of winter, but instead keeping mature plants alive for harvesting, and the established root system of the mature plants can handle the infrequent watering.

2) When possible, open your hoop house.  Excess water that would be lost through evaporation can’t escape when you have a closed up hoop house.  It can be so bad that it will actually rain inside your hoop house with condensation dripping from the ceiling.  At this point, you are basically growing in a terrarium.  If you have a warm and sunny day, open the doors or roll-up the sides for a few hours to vent the humid air.  I like doing this from about 10am until noon, and then closing it up again so the hoop house can heat up before night time.

3) Plant with more space.  Plants will rot less if air can travel between them. Kale planted 8″ apart will rot less than broadcasted baby spinach.  So, when possible, give your plants a little more breathing room.

I hope that with some effort, you’ll be able to have a successful harvest throughout the winter using your hoop house.  Do you have any other suggestions?  Feel free to leave them in the comments below.

One Response to Winter Time Growing in Hoop Houses

  1. Jay Marshall says:

    Vinnie,

    Have you explored supplemental lighting as an option during the times of year (primarily winter) when natural light is less available?

    I am scheduled to be in the Baltimore area in March and would welcome the opportunity to schedule time to review our LED technology with custom color spectra for horticulture.

    Jay Marshall, LC
    Illumitex
    Director, North American Sales
    559-903-1002

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