Many people think they are limited in what they can grow because they don’t have a green house. As long as you are growing plants that are hardy to your gardening zone, your plants will be okay outside over the winter.
Plants in the ground rarely need to be covered for the winter. They will freeze, but that is okay. Their roots stay constantly moist in the ground soil.
Plants in pots dry out much faster than plants in the ground. Harsh winter winds speed up the drying process. Its a good idea to protect your potted plants from the wind to keep the roots from drying.
We used our hoop house to cover some small plants that we were propagating as softwood cuttings.
Hoop houses are a simple way to protect your potted plants from drying winter winds.
You can build a simple, durable hoop house out of concrete reinforcing mesh. You can find it at most home improvement stores, such as Lowes, Home Depot or Menards. It is used to strengthen concrete in sidewalks and driveways. They are sold in flats sheets or on rolls. Its best to get a roll so that it will already be bent into a round shape.
We’ve seen homemade hoop house designs made from PVC piping or livestock fencing. Concrete reinforcing mesh is heavy duty. It will last you many years and can stand up to a heavy snow fall.
Check out these pictures of a large metal hoop house that collapsed under a heavy snow fall. Concrete reinforcing mesh will not collapse.
We used 7 ft pieces of mesh and cut them to fit nicely over our propagation bed. Small bolt cutters worked really well for snipping the thick wires. When we made each cut, we cut through the middle of a square. The protruding wires made handy little stakes for securing each section into the ground.
Once your frame is in place, you hoop house is ready to be covered. This is very important:
Do not cover your plants until they have gone dormant!
Your plants need several hours of freezing temperatures to trigger them into dormancy. Dormancy is a period of rest for you plants. Like a bear in hibernation, your plants will sleep and slow their metabolism. This helps get them survive the cold, dry winter months.
Once your plants have gone dormant, cover your frame with 6mil WHITE plastic sheeting. White sheeting is sold in nursery supply stores. You are not likely to find it in at a hardware store. Most hardware stores carry clear or opaque sheeting. If you cannot find white sheeting then paint it white with latex paint.
It must be white. It must be white. It must be white.
White sheeting will reflect the suns rays. Clear, black or opaque sheeting will heat up your plants during the day. Your plants must stay dormant for the winter. You don’t want them heating up during the day and breaking dormancy. Then they have to fight to stay alive in freezing temperatures at night. Its too much stress on your plant. They must stay dormant.
The purpose of a hoop house is to block the drying winds, not to keep them warm. Hoop houses don’t have ventilation or heat. They do not create an artificial environment like a green house.
Give your plants a good watering before you put on the plastic.
Large hoop houses, like the ones found at most nurseries are designed to be opened and closed. They are large enough to allow tractors and workers inside. It hard to maintain humidity in all that open space and with workers coming and going so large hoop houses have irrigation lines installed so they can water the plants every 3 weeks or so….the irrigation lines have to be winterized…its a lot of work.
Short hoop houses have less dead air space and allow for more humidity. They are designed to be closed tightly all winter. If you give your plants a good watering before tucking them away for the winter, they should be fine until spring. If you are concerned that they might need more water, you can poke a small hole in the plastic and spray some water in with a hose.
Cover your hoop house with one layer of white plastic sheeting. Pull it tight and make sure there are no gaps. Leave about 18 inches of plastic all the way around and weigh it down on all four edges with sand or soil. We prefer sand because soil is a muddy mess come spring.
Do not use bricks or lumber to hold your plastic in place. Trust me. Been there, done that, it doesn’t work! Wind will find its way in and tear your plastic.
Here is a helpful hint:
You can put large potted plants inside a small hoop house by placing them on their sides. Prop the first row up so they sit at a slightly diagonal angle. This will keep the soil from falling out of the pot. Prop your next row of plants up against the first.