Published by: Gourmet Sleuth
Last Updated: 06/26/2020
I have had a wood frame, polycarbonate-paneled greenhouse, a more “portable” seed greenhouse, and I built a rather huge (20 x 15) version of the wood-frame mentioned above. Each served its purpose, and unless you want something just “temporary,” I’d steer clear of the portable, seed greenhouse.
I love orchids. I love “summering” my other houseplants out in the greenhouse so they can grow strong and withstand another winter inside my house which offers little air flow or humidity. I love getting new orchids! I love having a place to put my orchids when they are at rest, forming their new orchid plumes (wrong word) for my future enjoyment.
I love starting garden vegetables from seeds. It’s so rewarding and it’s much less expensive than purchasing them already started. Also many times you are limited to the varieties you find at your local nursery. There are hundreds more types of seeds available, many are not commonly commercially grown for the summer gardener.
If you're going to buy a kit or have a greenhouse built for you, do it right. And by "right" I mean, don't skimp on the details. Don't think you can keep your plants happy if you don't provide for heat and cooling for your plants. Don't think you can just buy a structure, place the plants inside and water once in awhile, then walk away. Read on to learn about the many factors to take into consideration before you order your greenhouse. Let's get started!
Clearly a concrete foundation is good in many ways. Assuming it was installed properly, level, etc. It would be best to have the greenhouse all planned and selected before you pour the foundation. Aside from the obvious reason of making sure your pad is the correct size, you may want to set bolts in the concrete upon which you’ll sit the frame and bolt it to the concrete.
Cons: Concrete is expensive but worth it if you have the budget for it. Greenhouses get a lot of moisture you’ll probably have to deal with moss which can make the walking surface vert slippery. Your concrete person can do a “broomed” finish so the pad isn’t overly smooth. The concrete doesn’t really help keep moisture in the structure like gravel would.
Gravel makes a decent pad, again depending on the style of your greenhouse. If you are going super-deluxe then you’ll probably want something more permanent. The upside is the wet gravel will help with humidity in the greenhouse.
You can also lay brick or other types of stone pavers. These can be laid like any well-installed brick path or patio with a properly-prepared sand-bed below. These can look really nice.
Cons: Make sure you don’t have gophers in the area because they can undermine the pavers and create “dips” in the floor which can be a little tricky to negotiate. Just remember to keep in mind you don’t want a surface that will be slippery when wet.
You’ll want to consider if you want the greenhouse to sit on its own with the typical 4 walls & roof. This is a good choice unless you want to access it directly from your house. I’ve had 2 including the one I built for Charles (Jim’s dad).
The lean-to has 3 sides and attaches to your house or another structure. You can build it so you have access to the greenhouse from your other structure but this will involve some engineering to make sure you don’t create a moisture issue that could encourage mold.
These structures are super easy to build and cheap but don’t count on them to last more than 2-3 years. Read about how to build a portable greenhouse here. The upside is these are very inexpensive, typically about $100.00 or even less and they only take a few hours to construct. The downside is that they can’t easily be heated and cooled because there is just no real insulation. They'll also blow away if you don't anchor them down.
Small portable greenhouses work real well if you just want to get a jump start on starting seeds in your garden in very early spring. Typically they offer enough insulation to get seeds started. They don’t require a foundation. You can site them on a gravel bed or even on a lawn. They just aren't good for storing grown plants for very long.
Aluminum is more expensive than wood but it will outlast wood by many years. The frames can be plain aluminum finish or powder-coated in a variety of color. The walls may be polycarbonate or glass; this is true for wood greenhouses too.
Wood frame greenhouses are very popular and typically less expensive than aluminum. Redwood is a good choice because it holds up to moisture. Cedar is another good option. If you find any greenhouses made of pine, run in the opposite direction. Pine is soft will not hold up long-term to moisture. There are other wood options too. Hardwood is very expensive and less common, see conservatories below.
These structures are in a class by themselves. They are the structures you see advertised in the back of Architectural Digest. They are gorgeous, very expensive and typically custom built. They may be made of hardwood or aluminum. Typically they are heated, cooled rooms, appropriate for expensive furniture and specimen plants. If in my next life I come back as an aristocrat or an over-paid high-tech employee, I’ll have one of these. Check out Parish Conservatories if you want to drool over the possibilities.
Unless you have a carpenter in the family it’s best to purchase the benches made by the greenhouse company. They’ll fit the best and play well with other greenhouse components.
Typically you have two door options, a Dutch door (my favorite) which allows you to open the top of the door only to allow air flow and to cool it off a little while you’re inside yet you’ll still keep your dog or other critters out of the greenhouse. Or, the other option is to select a simple full-door.
You are going to want your greenhouse to have a hose bib so you can manually water your plants as well as support a “mist” system. If you have a very large greenhouse you may want a hose bib at each end.
You will need electricity. Although some systems for heating and cooling use solar, many still require electricity.
Use a good contractor so you get proper, safe, plumbing and electrical installed.
Think “greenhouse effect”. These rooms can get super-HOT in the summer. They can get so hot that you’ll fry your plants. A greenhouse without temperature control is a nightmare, I know from lots of experience of losing expensive plants. Good greenhouses will have venting that opens automatically to allow air flow. Depending on the size of the structure you’ll want a fan to keep the air moving – plants in structures don’t like stagnant air.
You’ll need a misting system to keep the humidity up and a humidity gauge so you don’t keep the air moist but not too “drippy” for your plants. Another fun gadget is a high/low recording thermometer like the one I discuss here. Clearly this is optional, but given you’re not in the greenhouse constantly it’s good to know the highs and lows of the day and night so you can make a necessary adjustments.
They’ll need shade cloth in certain areas because even the cooling systems can’t save plants from searing direct sun.
You’ll need heat for the greenhouse in the winter. Plants will get so cold, even in California, that you’ll freeze your orchids and other plants. Vegetables in the winter need enough heat to germinate seeds and encourage the setting of flowers and fruit.
Plants that get too hot or too cold or too dry will encourage disease and pests. Your greenhouse is no fun if you’re constantly fighting nature.