No, you don’t need a greenhouse

I often hear people say “I need to get a greenhouse” very early on in their gardening lives. They assume that a greenhouse is just one of those big things you need to “garden right,” like a hose and seeds.


I owned a greenhouse for four years, and while it had its good points, I am not in a hurry to do it again. Here are my observations, based on my own greenhouse, those of friends, and my stint working on a commercial organic farm – you make your own decision.

Particulars of my greenhouse

  • 8×12′ “barn-shaped” twin wall polycarbonate greenhouse – NOT very air-tight
  • No irrigation system (beyond dragging a hose in the door and watering)
  • Automatic vent openers failed again and again, so venting was manual (roof, gable end, and door). Rigged window screen and a low fence in the door to keep critters out when the door was open
  • Oriented on east/west axis (so the long sides faced north and south)
  • Very exposed site
  • Insulated with straw bales around base each winter
  • Southern Michigan, zone 5, min temp -30

Basic physics and maintenance

  • A greenhouse this size (or smaller) doesn’t have the thermal mass to avoid big temperature swings. There was a huge danger of freezing/cooking crops…perhaps in the same day.
  • In the winter, it was generally 5-10 degrees warmer than outside.
  • By May, it was regularly too hot for any cool-weather crops, even with the vents open.
  • Summer temps (with all vents/door open) were generally around 100 degrees.
  • Greenhouses are NOT good places for starting seeds, due to temp swings and pests. Much better to start indoors under good lights.
  • I could not water it enough in the summer months to allow warm-weather crops to thrive. And, because it wasn’t movable, it never really recharged the soil moisture over the winter.
  • Pests LOVE greenhouses. Aphids, hornworms, voles, chipmunks all flock in there because you’ve protected them from the elements and predators.
  • In short, you have to be much more hands-on in a greenhouse and provide for more of its needs than in an open-air garden.

Good points

  • Somewhat extended growing season.
    • Peas in greenhouse bore fruit 6 weeks before those outside (keep in mind, they were planted 11 weeks earlier than those outside).
    • Kale overwintered reliably and resprouted in spring, resulting in huge harvests in April and May.
  • Amazing to have a warm place to sit in the sun on sunny winter days.
  • Friends who have somewhat larger, better-sealed hoop houses (often with chickens/rabbits in the mix) have had much better luck with extended harvests.

If I did it again…

  • I’d make it bigger.
  • I’d use a solid, insulated north wall and add thermal mass in any way possible.
  • I’d have some kind of irrigation on a timer. Knowing myself, I can’t be bothered to water every day, and timed irrigation is the only way I’d keep the soil hydrated.

My conclusion

For me, home-sized greenhouses aren’t worth it. I will gladly buy produce from farms with commercial-sized hoop houses for the early spring months. I will start seeds indoors under lights. I will grow a few greens in a southern window of my house in February. But I’d save the money and hassle of another big thing to maintain and not buy another greenhouse.


Great day at the homestead

What a gorgeous gift of a day! Nov. 12th, but sunny and warm (60, by mid-day). Last week’s snow jolted us into realizing a number of chores that really needed to get done before winter set in, and we did pretty much all of them today.

Our neighbor, Gary, came over with his tractor and moved the giant pile of wood chips (20yd dropped off for cheap by a local tree service) to the various plantings that needed a fresh coat: the oak berm, the berry berm, and the apple/raspberry bed. When he was done, he moved the remaining chips (8 yd?) to a back corner of the property so they’re out of the driveway. As he did that, Scott and I started to take the pergola “roof” down, which lets the sun into the house and also keeps the pergola from collapsing under the weight of snow – I don’t think 4 year old willow fencing can handle a foot of snow!

This is always a shaky job – our ladder is just barely tall enough to get to one end of the pergola, and it sinks into the ground. It’s nerve-wracking and not terribly safe. Finally, Gary says, “I can’t take it any more! Scott, get in the bucket!” And in a move that looked more dangerous (but both guys swore it was better than the ladder), Scott gets in the bucket of the tractor and Gary lifts him up level to the top of the pergola, which we can then dismantle in record time. (I’m on the roof at this point, managing the slats that hold the screening on the top of the pergola, thinking I’ve got the safest perch of the bunch.) And heck, while I’m up there, I cleaned out the gutters, too.

When that was done, we trimmed a couple branches overhanging the deck, and finally called it a morning. After showers and lunch, Scott ran off to do Scott things involving coffee, and I decided to flop on the couch with a book, or the internet, or something. But! The living room is cold.

No worries! There is wood, and a fireplace. But! There’s so much ash in the fireplace that it’s hard to keep a fire lit. No worries! There is a shovel, and a tin for the ashes.  But! Now the ash tin is full. No worries! It is beautiful and sunny, and I can go dump them out by the greenhouse.

Oooh, greenhouse. I wonder how things are going in there? Pretty well, as it turns out. There’s actually a serving of green beans to be harvested, and the winter savoy cabbages are starting to head up. Hmm, cabbage – that reminds me, I was going to transplant the Storage #4s from the garden to the greenhouse to compare how they keep “live” to in the root cellar. Did I mention it’s beautiful and sunny?

And so on, for at least another hour.  And now the cabbages are transplanted and watered, one water barrel is empty (I don’t think they’re big enough for warm thermal mass, and since this one is on the north side, I’m betting it would freeze, making it the wrong kind of thermal mass), beans harvested, greens for dinner picked, and three cookie trays of herbs (oregano, rosemary, and sage) are drying on the kitchen table.

I’m a couple hours late to my flop on the couch, but so what? Now I’ve got fresh green beans to eat as I putter online. 🙂

On recent travel

So I spent 10 days in early May in Salo and Brecia, Italy, and in Amsterdam.  It was mostly a business trip, but there were some touristy bits on the side, too.

Hotel BelleriveMy hotel room (suite, actually) was very nice, and had a fully-stocked kitchen.  It was fun to see what’s considered essential in an Italian micro-kitchen: good knife and cutting board, mezzaluna, bread knife, poultry shears, corkscrew, espresso maker, colander, two sizes of coffee cups and saucers, wine glasses, plates and silverware.  No bowls at all, and no glasses over about 6 ounces.  The kitchen itself was a very clever built-in unit with the fridge underneath, and a dish drainer built into the cabinet above the sink so you could put wet dishes “away” and they would drip dry into the sink.  The sink water was hot enough to steam; it was very nice for filling the hot water bottle (which was a terrific travel accessory, I must say.)

Salo MarketNaturally, I hit the market as soon as I was able.  The market in Salo is mostly clothing and everything is vended from camper trailers with big awnings.  It reminded me of an American fair, as opposed to a market. I’m going to go ahead and show my local pride and say that the Ann Arbor Farmers’ Market is far and away a nicer market – better selection, better layout, no underwear.  I picked up asparagus, garlic scapes, carrots, an onion, a cabbage, a basket of strawberries, and half a dozen eggs – then I realized I had no fat or salt back at the hotel.  Sausage to the rescue!  It turned out to be a very bland type, but it was OK.  This became my breakfast each day, and a good thing, too; side dishes (i.e., vegetables) are ordered separately from the main course in Italy and tend to be very expensive ($10 for a side of grilled vegetables).  On the last day, I cooked my boss a vegetable fritatta but we couldn’t quite eat up all the leftovers.

Graffiti at "Juliet's Balcony"On our first day “off,” we went to Verona.  I saw many of the sights and had a very interesting lunch that included horse, donkey, and rabbit.  The rabbit was not to my taste; apparently, Verona-style rabbit is cooked (dried?) until it resembles jerky with a bone in the middle.  I found it basically inedible.  The horse and donkey, on the other hand, were quite good.  Two of the dishes had stewed equid (one on pasta, one with polenta) and they were quite tasty.  I honestly could not tell it apart from beef.  There was also a salad of arugula topped with finely shredded dried horse.  I liked the horse but I just can’t develop a taste for arugula.

Limone sur GardaThe next day, we took a boat up Lake Garda to the city of Limone.  Along the way, we saw the ruins of some curious structures – lots of columns, but no walls to be seen.  When we got to Limone, we poked around and saw some still in use as trellises in people’s yards. (Or as people’s yards; it’s a tightly-packed town on a steep hillside, pretty much carved out of the rock.)  A little more searching and we discovered the Lemon Greenhouse and Museum – and lo! It turns out the structures are about 250 years old and, with some rafters and glass added, serve as greenhouses for lemon trees.  Not surprisingly, limoncello was available in the gift shop. 🙂  I’m sure none of you were surprised that I managed to find a greenhouse where I landed on a business trip!

Tulips at Amsterdam flower marketThe last part of the trip was spent in Amsterdam, and I found that I liked it better than Italy – just a better fit for me, I think.  It’s a very livable place – tidy and orderly without being stifling.  Italy creates identity through a strong commitment to preserving the past in the forms of traditional foods, ancient buildings, and fierce city-by-city differences. For example, Brescia and Verona – perhaps 45 miles apart – have “completely different” styles of carpaccio – one has some mustard in the dressing and the other doesn’t, but it’s a matter of pride that those differences are there. The Netherlands seems to embrace variety: walking down a street in Amsterdam, you’d easily see cuisines from twenty or more different regions, and preparations the same dishes at each would be somewhat different.

Food notes on Amsterdam: Definitely loved Indonesian food at Kantjil & the Tiger – we got the “try everything” meal with a dozen dishes of wonderfulness.  Coconut curry beef was probably my favorite, but there was nothing bad on the table.  I found I prefer the small pancakes (Poffertjes) to the large ones (pannenkoeken, more like a crepe; very thin and eggy).  Meals typically end with a small dish of amazingly good chocolate (slabs of dark chocolate rolled in cocoa) and I believe this is the most perfect end to a meal I’ve ever tasted.

A few things got to me food-wise on this trip.  The first was, WOW.  I am really not a wheat person anymore.  After three days in Italy, I was desperate for some rice.  The bread and pasta were fantastic, but I really appreciate a lot more variety than I was getting at my string of restaurant meals.  I gotta say, if I don’t see another crusty roll with salty meat on it for a month, I will be perfectly satisfied.  And while I think Americans often rush through meals, I do appreciate being able to complete a restaurant meal in under 2.5 hours.  And in one final surprise, I think I’m getting hooked on sparkling mineral water – which is also surprisingly good for a stomach that’s feeling wonky due to an overabundance of wheat, too long between meal times, and an overcooked rabbit.

Terra Preta experiment

Ok, y’all know about terra preta, right? This is where you add charcoal to soil, and through the magic of microporus carbon and those wonderful, wonderful soil microorganisms, the soil retains fertility on almost unheard-of timescales. You put compost in a bed and you need more compost in…a year? Maybe two? Amazonian natives used terra preta a thousand years ago and that soil is still noticeably more fertile than the soil around it. So yeah, gotta try this. Since everyone who knew how to do this is now dead, the method is still being pieced back together. In its simplest form…you make charcoal, crush it, and mix it into the soil. I don’t really know how fine it’s supposed to be, or if it even works in temperate zones, but what the heck. Let’s give it a shot. I know folks in New England spread fireplace ashes on fields, so it probably won’t hurt, right? Lots of pics after the break… Read the rest of this entry »

The greenhouse, in pictures

So, last fall I was wondering if my comparatively tiny, low-thermal-mass greenhouse would ever be “worth it.” It’s the first week of May.  The greenhouse kale, which I’m letting go to seed, is literally shoulder-high on me. We’ve been flush with greens since mid-March. We’ve harvested about six pounds of Hakurei turnips and greens so far. I’ve grown my own kale, cabbage, and broccoli transplants and moved them outside.

Yes. It’s worth it.

Turnips and peas

Turnips and peas and onions

Kale, etc.

Podding radishes (front), Haurkei turnips, kale (going to seed)

Hakurei turnips

Hakurei turnips. Addictive!

Greenhouse door

Looking out the greenhouse door. Alliums on the left, podding radishes on the right.

Podding radish flowers

Podding radish flowers. The seed pods on these will get as big as small green beans. I want to try pickling them.

Kale flower

Wild kale flower. Eat like broccoli, or gather the seeds after the blossoms fade.

Quick update: Planting in March

So I’ve been doing quite a lot lately, but blogging about it hasn’t been a priority…here’s the run-down:

  • The root cellar has been fully insulated, sealed, and painted. The ventilation is 1/2 done and the shelves are planned. I hope to get to those things this weekend.
  • Planting! In the greenhouse, I have kale, cabbage, broccoli (3 kinds), podding radishes, peas, and turnips (hakurei and golden globe, both salad turnips). In the garden, I have regular cooking turnips, rutabagas, onions, rhubarb, and peas and I hope to get the first batch of carrots and parsnips in this weekend.
  • Planted 3 blueberry bushes and a Meyer lemon in containers.
  • Is that it? Wow. That all felt like a lot more work when I was *doing* it… I guess I could list garden bed prep and buying 30 pounds of seed potatoes as things done.

I won’t bore you with the yet-to-do list…

Greenhouse kale: row cover makes a big difference!

This winter, my greenhouse was filled almost entirely with kale. The leaves held up very well to the cold, though by January, the stems were pretty knackered from the alternate thawing and freezing. In min-January, I harvested all the remaining leaves from all the plants (leaving only a couple tiny leaves in the center of the rosette on some of the plants) and figured kale production would shut down for a couple months. That’s pretty much what happened, but look at these pictures. You might want to click on them to view bigger versions – the dark purple kale doesn’t show up very well on the black plastic mulch.

This is a picture of the end of the bed that had no protection except the greenhouse itself. Keep in mind, this is a very small greenhouse in a very cold microclimate, and we had almost no sun at all this winter. We had two sunny days in a row last week, and I think that’s the first time that’s happened since November. *sigh* So temps in the greenhouse were under freezing every night, sometimes as low as 5 degrees this winter. (Though the soil did not freeze much at all – small patches for a few days at a time, not frozen solid like last year. Yay, raised beds!)
Kale w/o row cover through the winter
You can see these stalks look almost dead. They aren’t – there are tiny leaves starting to sprout in the crooks of the the old leaf scars on the stems – but it’s clear these plants need several more weeks before I can think about harvesting again. The couple leaves of the dino kale in the foreground were there all winter but don’t seem to be helping the plant recover much.

Now contrast this kale. Look closely – you might need to zoom in – but you can see the leaves are about the size of my palm and growing fast. These plants are the same variety as the others, but they had some row cover draped over that PVC frame. Quite amazing what a difference it makes!
Kale that had row cover through the winter
I love the color of this kale. The new leaves have started out as the deepest, richest purple I’ve ever seen on a plant leaf. As they get bigger (and perhaps as they get more sun,) they get some green in the center of the leaf. They are so sweet, they almost don’t taste like kale. Not a bonus, in my book, but interesting nonetheless.

The plants that survive the winter and the varying heat of spring win the lottery: I’ll let them go to seed and harvest my first brassica seed to save for next year!

Psycho cannibal voles

I have quite the vole infestation in my greenhouse. The ground is polka-dotted with tunnels as they sweep through, eating every earthworm they can find. This weekend, I decided to fight back, and set out traps.

When I first went out, one trap was sprung, and the other was…missing. I finally found it several feet from where I’d set it. It was wedged into a fresh tunnel, sprung, but empty. Or so I thought.

When I opened the trap, there was the head of a vole, neatly trimmed off to the edge of the plastic trap. All I can conclude is that one of its fellows dragged it (trap and all) to the tunnel, where it was eaten by its brethren.

Or perhaps they just took as much of it as they could for a proper volish burial. But somehow, I’m more inclined to believe voles are just nasty little carnivores.

I caught two more that afternoon and threw them out immediately. I haven’t checked the traps in over 24 hours, though, and I’m wondering what I’ll find when I go out there tonight…

Greenhouse: Nov. 6th, 2009

Pea flower


Greenhouse view

As of today (Nov. 19), the kale is bigger, and the green beans (in the cold frame) are blooming. The total pea harvest has been 7 pea pods…but wow, is it cool to see blooms in November! There’s also some Purple Peacock Broccoli and Happy Rich greens (like rapini) sprouting between the leeks and the cold frame – we’ll see how long that makes it.

The goal with the kale is to keep us in greens through January, and to protect the stalks so they can re-sprout early in the spring. We’ll see how that goes!

Greenhouse year in review – 2009

DSCN1452It’s been a mixed year in the greenhouse. I wouldn’t call it an unqualified success, though it had its good points. Here goes:

The Good

  • I got to start gardening March 1. Not a whole lot *happened*, but it made me feel good.
  • The peas in the greenhouse bore fruit 6 weeks earlier than the peas outside.
  • The green beans planted in late August bore about 2-3 weeks earlier than the beans outside.
  • The yellow pear tomatoes in the greenhouse were the only tomatoes that produced anything at all this year.
  • Topless sunbathing in late February!

The Perplexing

  • The greenhouse peas took 11 weeks to bear. The ones planted outside took nine weeks.
  • The hot-loving vegetables didn’t love the greenhouse. They looked pale and sickly. The okra was under a foot tall and produced five pods between two plants.
  • The greenhouse only held 5-10 degrees over the outside temp during the cold months, and even less than that in the summer.

The Downright Annoying

  • Aphids. Everywhere.
  • More tomato hornworms than I’ve ever had in all my gardens combined. Ok, that’s still only 5, but…
  • Occasional rabbits and chipmunks inside the greenhouse, snacking, building nests, having late-night poker parties, and generally carrying on.
  • The gutters broke off in a late-season snowstorm. Even when I got them back up, they didn’t collect enough water to make water barrels worth the trouble.

So here are my theories about what’s going on.

  • The soil in the greenhouse is the worst soil in my garden. I put down 4″ of composted horse manure last October and planted in that. In my regular raised beds, I don’t need to dig at all; by the end of the season, the roots and worms have done all the work. However, the clay under the greenhouse was smoothed off with a bucket loader before we built, and that clay layer remained impermeable. When I stuck a digging fork in last week, I was shocked (as in, jolted up the arms and into my bones) to discover the “soil” was 2″ deep over a rock-hard layer of hardpan clay.
  • I need to water the greenhouse every day. Maybe that’ll improve when I improve the soil, though.
  • An 8×12 greenhouse does not have the thermal mass to hold temperature. It heats up too fast and cools down quickly, as well.
  • This greenhouse model – a Rion kit – is probably also just leakier than your standard polyfilm hoop house. I bought it because it’s pretty, but I don’t think it’s as functional as a plastic quonset hut.

What I’m going to do:

  • Build raised beds inside the greenhouse – 8″ deep. Fill with composted horse manure and dig it in to break up the clay layer. This will improve the soil drastically and let the soil heat up faster in the spring. Better soil will retain water better and help the plants be stronger, both for growing and for staving off insects.
  • Install a brick path down the middle to retain some heat. Even if it doesn’t work, it’ll be neat; my folks are going to loan me some bricks from the brick walk around the train station I grew up in (scroll to the bottom…), so there’ll be a little of my growing-up homestead in my adult home.
  • Be better about watering next summer.
  • Place bales of straw around the perimeter to stave off the freezing of the soil to extend the fall harvest.

« Older entries

%d bloggers like this: