Saturday, April 30, 2016

On Starting Seeds and Greenhouses

Another couple of rainy, windy, cold days here in Iowa, so I'm inside again, starting a few last seeds and thinking about the process and how I might improve it. The seedlings in the picture above are the petunias I experimented with growing from seed this winter.

I was feeling spendthrift and lazy just going to the nursery and buying flats of petunias and other annuals already started, so I decided to try starting some petunias from seed in mid-March to see how it went.

I have started seeds before and it's usually worked fairly well -- the vegetable seeds I've started for my husband have been quite easy, and I've also started biennials like wallflowers and perennials like the 150 dianthus that edge my four L-shaped pond garden beds (although those are started in late spring and potted up outside until they are planted out in late summer, so they are different than starting seeds indoors under lights in winter and spring).

I bought a soil blocker this spring and used it for the first time with these petunias, and it worked quite nicely. As you can see in the photo, the petunia plants are coming along fairly well, although I had problems with uneven germination and size of plants.

Petunias are not the easiest plants to start from seed and grow inside -- first, they require at least two months of growing in warm, bright conditions, during which many things can go wrong: damping off (I run a small fan nearby to keep the air moving gently), drying out if you forget to water them or go away for a few days, and probably numerous other maladies that can afflict them. And the seeds are quite tiny, so Burpee's (the ones I found locally, so I didn't have to pay for shipping) are pelletized for easier handling, which is fine with me, but that makes them more expensive, and only half of the 50 seeds (2 packets) that I bought germinated, which is disappointing.

I also have some sweet peas and dahlias started from seeds on the top shelf, as well as some freesias just coming up in the pot below. The lights plug into a timer on the wall, and a small fan is on the floor nearby.

To grow them in my basement, I use florescent lights and a heat mat under the flat, both of which cost money to operate (even independently of their purchase cost). I calculated that the 24 petunia plants that I have managed to grow to this point have cost me more than three times as much, per plant, as buying them already in flower from the the least expensive nursery near me:

Cost of 24 Petunia Plants:

$ 3.00    50 Seeds (2 packets @ $1.50 each, only 24 of which germinated)
$ 2.00    Seed Starting Soil
$ 6.50    Cost of running two 32W light bulbs for 14 hours/day for two months
$ 2.50    Cost of running heat mat for two months
$ 3.00    Cost of running small fan (for all seeds)

At the Amish nursery near me, a six-pack of petunias costs only $1.29, so 24 petunia plants costs $5.16, less than a third as much as it cost to raise them myself. Even if all 50 seeds had germinated, it still would have cost $17 for 50 plants, compared to $10.75 for 50 purchased plants, which would still be nearly twice as much. Hmmm!

Now, I know that not all plants take as long to start as petunias, and that there are other reasons to start plants from seeds besides saving money: only a limited selection of plants are available as starts locally, so if I want special varieties, I will have to grow them myself. Also, I'm serious about my hobby of gardening, and there's the argument that I really can't consider myself to be any sort of knowledgeable gardener if I don't know how to successfully propagate plants.

So I still want to be able to grow things from seeds, but I might have to re-evaluate how I do it. Much of the cost in my calculation comes from the long periods of running lights, which I would not have to do if I had a small greenhouse.

A Greenhouse?

Now, greenhouses are very common among British gardeners, who can hardly imagine gardening without one. But they're fairly uncommon here in the US, for several reasons: first, it gets MUCH colder here, so it costs a lot more more to heat a greenhouse in winter. (In England, many places hardly get below 20°F, compared to below 0°F here.) Also, it doesn't get as warm there -- in England, many gardeners grow tomatoes in greenhouses, because they just don't get enough heat to grow them outside. Here, a greenhouse is practically unusable in the hotter months (unless it is to sterilize soil).

Many British gardeners can hardly imagine gardening without one of these. (Hartley Botanic)

But this is more like what I'm eyeing: a 4'x8' lean-to style greenhouse.
(EarthCare Greenhouses)

I've been considering getting a small, relatively inexpensive greenhouse for several years now, but I wasn't sure where I would put it, until a few months ago a place occurred to me: The south side of my garage.

I had tried planting sunflowers and iris there to make it look less ugly, but I have realized that I should just consider it a "utility area" and use it as such. I removed most of the plants last week and will at least put a cold frame or two in this spot.

This area on the south side of my garage will never be pretty, with the gas tank, vinyl siding and tiny, ugly window. But it does get full sun and is relatively protected from wind, as well as being near electrical outlets inside the garage.

The eight-foot-long greenhouse would be just to the left of the gas tank, and the garage window could be replaced with a small insulated door, as the inside framing is already appropriate for that. Opening the garage greenhouse door on cold days would release less heat from inside the greenhouse than an exterior greenhouse door would.

I would probably only use the greenhouse in late fall, to protect tomatoes and herbs from frost, and in early spring, to start seeds. I could run a small portable heater on a thermostat in spring to keep the temperature above 50° or so. There would be a cost of heating the greenhouse (I have calculated using an online greenhouse heating calculator that during the months of March and April it would cost about $25/month to keep it at 50°), but the cost could be averaged over a number of flats being started at one time. Perhaps I wouldn't be able to start warm-season flowers and annuals in there until mid-spring, but cool-season annuals and vegetables would probably do well in there earlier in the year.

Of course, I can buy a hundred flats of petunias for the cost of a greenhouse, even the the inexpensive one I'm considering. Realistically, I will probably never justify the nearly $1,000 it will cost me to set up the greenhouse. But on the other hand, it might be fun to have one, and it might make me a more knowledgeable and experienced gardener (or it might just be a place to sit out of the wind on sunny, cold days, or just end up as a place to store pots, like so many gardeners' greenhouses end up...).

I'd like to ask readers, particularly ones gardening in cold climates, whether you have ever used a greenhouse successfully, and for any tips or recommendations on doing so (or not doing so, if you recommend against it).

Thanks for reading, and I hope your own seed-starting efforts are going well this spring! -Beth


  1. I have to agree, there's little money to be saved by starting plants from seed. I mostly do tomatoes and peppers so I can get them out early and get the varieties I want. I do purple coneflowers and a few others that are a little expensive and don't always return each year, but I don't have the expense you do...mine get moved in the garage at night and out in the sun each day. There's just something satisfying about growing a plant from seed. Happy gardening..._Janice

    1. Hi Janice, You're absolutely right, that starting things from seed is very satisfying, independent of the cost. I had never thought about how it's done in warm areas -- thanks for commenting about it. And thanks for reading! -Beth

  2. I also try starting plants from seeds every year. This year it's tomatoes and chili and I want to start zucchini, cucumber and pumpkin. Last year we had such a cold summer in northern germany that I did not harvest one pumpkin.

    It is interesting for me what you write about greenhouses, because here it is also very common to have one while there are a lot of summers that are not too warm. I also dream of having one, but at this time I have too much projects in- and outside, so the greenhouse ist not on top of the list. But since I had only a small harvest of tomatoes the last two years when the plants were outside I bought two little tomatoe-houses so I am looking foreward of more success this summer :-).

    At the moment I have the same problem as every year - the plants are growing and I need more space, but outside it is too cold, even in the tomatoe-houses. And I should start the pumpkins....

    1. Hi Birgit, I had no idea summers were cool in Germany and that greenhouses are common there like in England, but I guess that makes sense. I wish you better luck with your tomatoes and pumpkins this year -- thanks for stopping by! -Beth

  3. I grow some plants from seed, but so far mainly by sowing outdoors directly where I'd like them to grow. (I tried starting seeds indoors once by a window, but concluded I don't have enough light to make it work without a grow light.)

    I grow seeds for plants - like partridge pea or wild senna - that I just can't find at nurseries (either locally or mail order).

    Plus even if I *could* find the plants at a mail order nursery, they'd probably cost $5 to $10 each for a small pot, whereas a packet of seeds might cost just $1.50 or $2.

    So the economics make much more sense for rare/unusual/hard-to-find seeds, IMHO. Or for particular varieties of vegetables where you can't find starts at the local farmers market.

    Plus of course if you're growing the plant from seed yourself, you know what sort of fertilizers you used, if any. If you buy a plant from a nursery or market, you don't really know what was sprayed on it.

    The greenhouse might not make sense financially, but if it gives you a happy place to potter on sunny winter days, then perhaps it's worth it for its 'soul value'? :)

    1. Hi Aaron, Thanks so much for stopping by so I could find your blog! You're totally right that it's in growing uncommon plants that would be expensive to order as potted perennials that money can be saved by starting them yourself. And I especially like your 'soul value' argument... :-) Great to meet you! -Beth


  4. Hi Beth! Well done for sowing so many seeds successfully. I was reading about one of those soil blockers the other day and it sounded like such a time saver if you start a lot from seed so I'm glad you had success with it! I loved seeing the picture of the English greenhouse and you are right it's just so normal for most gardeners there to have one. We even go sit out there and drink tea on a cold day just puttering with plants! I have lots of happy memories of sitting in my grandmothers and eating tomatoes! My sister in England has one very similar and grows sweet peas in late winter and starts all her seeds that way. Its fabulous! Obviously I am not the one to give advice on getting a greenhouse being in Florida (!) but I think if I ever lived anywhere colder I would definitely find an excuse to get one! Hope you can!
    - Kate xx

    1. Hi Kate, Thanks for your encouraging words (again!). And I love your lovely stories about time spent with family puttering in greenhouses when you were growing up -- who wouldn't want opportunities to spend time in that way? Thanks for sharing your greenhouse experiences! -Beth

  5. Hi Beth,

    You do not seem to be calculating the joy and fulfillment you would receive from the greenhouse. There is something deeply satisfying from rounding out your garden experience with a greenhouse. Also, I'm not sure if you said it it in jest, but sitting in the greenhouse on cold days is great! You have the feeling of being both indoors and outdoors. It is a favorite memory from when my boys were young! Think of it this way. You will save buckets of money on vacations to warm weather climates by sitting in your greenhouse! You laugh, but wait and see. I look forward to your confirmation years from now!

    Love your blog.


    1. Hi Linda, You are so right about the joy and fulfillment -- and also about the money I would likely save on expensive vacations by having a greenhouse to putter in during late winter and early spring. The value of those experiences are pretty hard to quantify with numbers, though... But you're pretty persuasive. :-) I'm so glad you stopped by -- thanks! -Beth

  6. I start a lot of plants from seed because the annuals at the nursery are full of pesticides and my garden is organic. It might take a few years for the grow lights and heat mats to pay for themselves, but having clean plants is worth it! I think putting a greenhouse in that spot is a great idea. :o)

    1. Casa, you're absolutely right that starting plants yourself gives you complete control over the entire process, and is a very good reason to have the tools to do so. Thanks! -Beth

  7. Hi Beth, I replied back to you on my site as well. I love the little lean-to style greenhouse! I only recently opened my greenhouse back up as it is just too expensive to heat during winter. The smaller one would probably be much easier to heat, though. I do use my greenhouse for my tomatoes and peppers during the summer. I hang up a white shade cloth that lets through less light, and I spray water on the floor of the greenhouse to cool it. It definitely extends the season through fall for me, which is nice! I do have to say, I've grown petunias from seed before, and they took so incredibly long that it wasn't really worth it for me either.

    1. Indie, thanks again for your response! I'm so glad you are able to use your cool new greenhouse for seed starting and other things. I'm looking forward to seeing photos of it on your blog some time. Best, -Beth

  8. I also tried to grow petunias from seed....too expensive....and I am reconsidering certain flowers or veggies to start from seed.....time and expense. I also would not get a greenhouse...too expensive to heat. We had one at our tech school and didn't use it in winter much due to costs.

    1. Hi Donna, I agree, heating a greenhouse in winter is not cost-effective for colder areas like ours. I would probably use it only to extend the seasons in fall and spring, with minimal heating. It's true: annual starts are so cheap to purchase that it's hardly possible to save money doing them, unless perhaps you are starting a large number of the same variety. Thanks for your input! -Beth