DIY Greenhouses

My neighbor Sherry has a gorgeous greenhouse in her backyard. She inherited some money years ago and splurged on this garden structure with a mortared stone floor, beautiful windows, and exterior designer details. And when I say splurged, I truly mean it — it’s a work of art that houses her tropical plants during the winter months and gives her a place to start cuttings and keep garden supplies. Few us of have that budget, however. So, if you need a space to protect your plants over the winter and to start seeds in the warm months, there are a few DIY greenhouse options for you. Let’s look at some of the key factors that make it worth-while to have a greenhouse.

Benefits of a Greenhouse:

  • Longer Growing Season
  • Pest & Predator Protection
  • Optimal Growing Environment

How Big Does a Greenhouse Need to Be?

If you want to start out small with year-round gardening, the smallest types of greenhouses are simply individual beds that you have turned into cold frames in order to protect a few delicate plants. You can do this by securing some plastic sheeting or by placing glass windows resting on top of the bed. You will want to construct these It’s so that the row cover is not laying directly on the plants and can be lifted up if the sun gets too warm.

Do I Need To Heat My Greenhouse?

To heat or not heat will depend on how cold your winter gets and on what plants you are growing.

  • First, know what temperatures your plants need for optimal growth.
  • Invest in a thermometer to monitor the soil temperature of your plants.
  • Use low tech temperature control where you can. A horticultural fleece or bubble wrap can provide insulation on or around your structure or plants.
  • Use proper ventilation to keep moisture down and trap warm air on sunny days.

When heat is needed:

  • Selectively heat when possible by grouping plants together.
  • Use heating mats and heated propagation stations.
  • Use electric heat if possible, it is safer and does not add extra moisture.
  • Propane and paraffin systems can be used when no electricity is present, take care to watch for moisture and mold.

Some DIY greenhouse designs require following a set of plans or assembling a purchased kit, while others are much simpler and use found or repurposed materials— but if you’re handy and know your way around some basic power tools and possess a few carpentry skills, this could be a project for you. If any of these projects sound interesting to you, a quick Internet search will produce numerous tutorials.

Homemade greenhouse raised garden bed with young lettuce and other vegetables being grown. Modern gardening, winter production, organic gardening, homegrown produce concept.

DIY Greenhouse Design

Cold Frame: Cold frames aren’t greenhouses per se, but they perform the same function — to protect plants during the winter. So, let’s say you have some seedlings or small herbs to protect. You could build a wooden box with a clear plastic hinged lid to place over these tender plants, and you’re good to go.

Lean-To: Lean-to’s are kind of mini-greenhouses that utilize an exterior wall of your house or shed, almost like a small conservatory. Using wood and cut glass or corrugated plastic, build a 3-sided structure that attaches to the exterior wall of your choosing to keep your tender plants safe and sound.

Repurpose & Reuse: DIY Greenhouse Design

PVC Hoop House: This is a great project for those of you who have rectangular or square veggie gardens that are in need of some protection. Long pieces of PVC pipe are used to create a hoop from one side of the veggie bed to the other — simply pound a few rebar stakes into the ground on either side of your bed, then pop one end of the PVC pipe over it and arch it to the other side of your bed, into another stake. Then cover with your preferred material.

Trampoline Greenhouse: I love this option, because it repurposes an old item that many people already have — the trampoline your kids no longer use. The idea is to cut the trampoline frame in half so that each half now becomes the front and back end of your greenhouse when set on end. Cover it with freeze cloth or plastic, add a rudimentary door, and viola! You have a greenhouse.

DIY Greenhouse Materials: Glass vs Plastic

Window Frame House: I’ve seen images of window-frame greenhouses over the years, and have been itching to try it myself. Home resale shops or garage sales are great places to pick up old windows, which can then be fastened together to create your structure. It takes a little more work than some of the other DIY options, but it’s a charming and effective solution.

Perfectly Plastic Greenhouse: Glass can be hard to find or too expensive to use, there are other non-glass options to consider for your DIY greenhouse. Fiberglass, vinyl, and plastic like Polyethylene or Polycarbonate are excellent materials to use for your greenhouse. They are durable, light-weight, cost-effective, can have UV protection, and last years. These non-glass options can come as panels corrugated or straight, sheeting, or film.

greenhouse in the fall

3 Steps to Prepare Your Greenhouse for Fall

1. Clean the greenhouse. Begin by removing and disposing of any existing greenhouse plants that are dead or diseased. Discard any trash, broken pottery, old soil bags, or garden tools that are beyond repair. Declutter, clean, and organize the tools that are left over. Sweep the floor and give it a good once-over with a soap-and-water washing, then hose the floor down to remove any lingering residue. Wash the framework, glazing, and any existing benches — you want to have a clean exterior to allow sunlight in, and a clean interior to do your work.

2. Inspect the structure. Now that everything is squeaky clean, turn your attention to the actual greenhouse structure. Check the glazing for cracks or gaps, and caulk any gaps in the insulation. Examine heaters to make sure they are safe for use and double-check all of your exhausts, vents, and ducts. Drain your water lines, cover the exterior faucets with insulation, and fill any existing tanks (oil, gas, or propane). If necessary, line your north interior wall with extra insulation (plastic sheeting or bubble wrap) to protect against chilly northern winds.

3. Move in your plants. Inspect all of your plants before moving them into the greenhouse — no pests and diseases allowed! Use your garden hose to run water through potted plants to dislodge and flush out any pests, and hand-pick off larger bugs on foliage. If necessary, use an organic product to further remove any unwanted guests. Clean your plants up by removing dead or diseased leaves. Wipe off the exteriors of your potted containers, and thoroughly clean out your empty ones — you don’t want to bring dirty containers into your clean greenhouse, and you’ll be happy everything is ready to go next spring.

Tip: Even if you don’t plan to move plants into your greenhouse this year, go ahead and complete a seasonal cleaning and inspection. This is the best way to keep your garden investment in top form, ready for work once the weather warms up.

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