Thursday, July 4, 2013

Greenhouse Story

Tina asked if I would post about my greenhouse.

Rain, July 2013

A greenhouse? Why?

Doesn't every gardener wish for a greenhouse? I trundled a kitchen cart in and out of the tool shed with little flats of seeds until after the last frost every spring. My winter projects of potted tropicals and rooting cuttings got too ambitious for an unheated utility room where it never got below 45 degrees and morning sun came in two east facing windows. When my Epiphyllum broke in the wind and I rooted the pieces, 3 huge pots were too many for the utility room along with forced hyacinths and other goodies.


What did you consider when you decided to build a greenhouse?

Costs, of course. Convenience to the house. A place in the winter sun for the pets and plants and me out of the wind. A playhouse, if you will. Size matters, too. Ten by 12 feet is just big enough for my purposes. It keeps me from being too ambitious.


Why did you choose an aluminum frame?

Cost and ease of assembly. I had a collection of old windows that I'd planned to use. I read many posts on Garden Web by gardeners who had assembled and used a Harbor Freight GH with good results. Replacement parts are easy to obtain despite having a long wait sometimes. We gave away the old windows with their need for scraping and reglazing and a huge carpentry effort and  undertook a project that was more suitable for two old people.

Isn't a greenhouse terribly expensive?

Less than a nice vacation. This is one of the most inexpensive aluminum framed ones, retailing at $899. Reinforcing it for sturdiness, a good foundation, and putting in water and electricity doubled the cost.

After four years, a hailstorm took out most of the polycarb panels that were brittle from our hot south Georgia sun. We replaced the panels. The frame is still sturdy. Be aware: An inexpensive greenhouse needs lots of reinforcement to make it sturdy and strong enough to withstand a hard wind.

Winter, 2012

Most of the inside is outfitted with odds and ends except for a nice cedar potting bench that was a present from the children and a shelf unit from a big box store that was not expensive. The benches are scrap wood. I use things like an old metal kitchen cart, an old medicine chest and a wicker bathroom shelf unit that the cat uses as a bed when he's out there.


Can I put up a greenhouse myself?

Help needed depends on how you usually get work done. It was strictly a DIY project for He-who-mows and myself. We put the frame together in the workshop out of the wind, put it on a flatbed trailer and hauled it around to its final location where we added the polycarb panels and installed the utilities to Code.

The water source is simple, a single faucet with a Y connector and two hoses, a short one for watering and misting and a shorter one for filling my watering cans. I hand water because I move things around so much and every pot has a different need.

Spring 2013

There are multiple electrical outlets with weather-proof covers and Ground fault interrupters on all. There is a timer that I use sometimes. A sending unit lets us check the temperature and humidity from the house.


How do you heat and cool your greenhouse?

We use two small electric heaters with fans and thermostats. If we have a really, really cold night I can also bring in some infrared lights. In a real emergency situation we can use a kerosene heater or a generator.

We have some occasional temps in the teens during nights in December to February. Comes the sun in the morning and things heat right back up. Ventilation is more of a concern than heat most days. There is an exhaust fan at the east end and a mist system for cooling.

The overall temps are moderated with heat sinks: four 50-gallon barrels of water. Lots of stone and concrete and brick used as flooring help take up heat from the sun on cold days. Wetting the concrete  helps lower the heat by evaporation on hot days and raises the humidity.


Do you grow year-round?

The heat is too intense in late spring and summer, I thought. However a purple alternanthera seeded itself under a bench and grew all summer. It is weaving itself among the pots now. A seedling Madgascar periwinkle came up too and survived most of the summer without water.

I leave a few tropicals in there through the summer on the floor underneath the mist system. I hung some non-woven material similar to row cover to shade the west end for summer.


What are your favorite plants to grow in the greenhouse?

Many plants that are root hardy here I like to see growing in the winter while the ones outside are killed back to the ground, slow to emerge come spring. Some of the gingers are dormant regardless but Alpinias stay green. Begonias and Kalanchoe do well as do Pentas and Porterweed for winter blooms. They can go back outside for the delight of butterflies in spring. Duranta cuttings quickly put on buds. White Shrimp plant and Persian Shield bloom in winter or early spring in the greenhouse.

I always force some bulbs. Amaryllis bulbs are the most spectacular. Hyacinth bulbs chilled for forcing in soil are great Christmas gifts. If they don't bloom on time, they're a present with a future. People like watching a bulb unfold. Kalanchoes and Christmas Cactuses are favorites, too.

Seeds, don't forget seeds! Early start on spring growing, patience with slow tropicals.


What tips do you have for someone thinking of getting a greenhouse?

My Daddy always said to estimate the cost and double it; good advice. Plan for a water source and electricity. Get some idea of what it will cost to heat your greenhouse. Pay attention to site and leveling.

Find all you can about what others in your part of the country have done. Learn from their mistakes and successes so you don't have to trial those again.

Maybe what you want isn't a greenhouse at all; just a playhouse or potting shed. A place to play and dream should not be beyond your reach.

Fall 2012


  1. I used visquene on my greenhouse that only lasted until spring which was good timing...but I am wondering if I should use different's domed shape so I doubt panels would work at present.

  2. Love your greenhouse! Definitely a dream for me. For now our basement is our 'greenhouse.'

  3. Thanks for this, all this advice came at a good time. I would love to grow more tropicals here, but would definitely need a greenhouse for that. I'll keep dreaming and looking into it.

  4. Great information and advise! I really like your last photo. There was a greenhouse on our property many years ago. When we moved here, all that was left was the foundation, and eventually we knocked even that down. Now that I have become a serious gardener, i wish I had that greenhouse!

  5. Nice post about your sweet little greenhouse Nell. I always enjoy reading about it and seeing photos.

    Hope you are having a nice 4th.


  6. It's a lovely greenhouse. What a great place to hang out! You have done a good job with it. Thanks for posting about it.

  7. This was a very interesting post. Thank you.

    I waver between wanting one and knowing I don't really need one. Basically I just need a place to grow on plants once they are transplanted out of seedling trays.

    Don't you ever use a shade cloth? Here it is critical even in early days of spring. That is maybe because my only ventilation was just opening the door on one end and a window on the mechanicals.

    Now it would just be a luxurious treat for me.....still haven 't ruled it out. Yours is the perfect size for my needs. Finding a spot without morning shade is the big issue.

  8. Your greenhouse looks wonderful! I've always loved the idea of a greenhouse but, for my purposes, I make do with the potting bench I have to provide room for puttering and the sense of sanctuary that fits my greenhouse dreams. Our biggest weather-related problem is the summer heat and, sadly, I don't think a greenhouse would help me there.


I look forward to comments and questions and lively discussion of gardening and related ideas.

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