Saturday, May 24, 2014

Greenhouse, Heart of Winter: Year 1

To wrap up the first year of gardening in the greenroom – March 2013 to the present, May 2014 – I wanted to write up our greenhouse growing successes and failures. This first year was highly experimental, especially growing through what I’m calling the “heart of winter,” and I think we learned some very interesting things that will help guide next year’s plantings, both the timing and the varieties. I’m more interested in “heart of winter” greenhouse gardening than mere summer-season extension gardening because this is all the fresh garden produce we get during the middle of winter. Shoulder season (spring/fall) crops and using the greenhouse to extend the summer season will be discussed in other posts; this is all about what we tried, succeeded, and failed to grow during the coldest and darkest months of the year.

Attempted crops for the heart of winter greenhouse season included basil, beets, Brussels sprouts, chard, cucumber, kale, lettuce, okra, peas, peppers, radish, tomato, and a few herbs. The short version: we’re going to become radish farmers! Much, much more detail is given below.

Heart of Winter” Summary:
Successes: Beets, Chard, Coriander, Kale, Lettuce, Radish, Tomato
Semi-successes: Basil, Broccoli, Leeks, Hot Peppers
Failures: Brussels Sprouts, Cucumber, Okra, Parsley, Peas, Thyme

I keep track of planting dates, harvest dates, quantity and quality of produce, and we also concurrently have some temperatures sensors outside and inside the greenhouse. Still, this is very much a crapshoot at this point as we figure out what we can grow in the greenhouse without supplemental lighting and only minor supplemental heat (to keep it just above freezing).
Frosty greenroom on a cold winter morning.

There wasn’t a real rhyme or reason to the timing of planting during this first, experimental winter greenhouse season; due to misdirected attention (to the summer garden), I missed the autumn August/September planting opportunity while the days were still long, so the first set of tests I performed were an October planting for these crops that I’m calling “Heart of Winter” – that is, plants that would have to withstand short days (no artificial light) and air temps down to almost freezing in the greenhouse. To make matters worse, during sunny days (most winter days are sunny here in New Mexico) the greenhouse gets anywhere from 90 to over 100 degrees depending on whether we open the doors to the house. (The design and some basic temperature data from the greenhouse are discussed here.) Let’s say the “heart of winter” plantings run from October to mid-January, as plantings in February begin to take advantage of the lengthening days. Let’s call those the Spring season, because that’s when they’ll be harvested (keeping in mind that this is all still referring to greenhouse growing, not outdoors, but there are seasons in the greenhouse too).

Here’s a handy infographic to help categorize the different categories/seasons of plantings we’re attempting in the greenhouse:
Greenroom planting categories.

Because we’re still just beginning to understand the success of the “Spring” plantings right about now, I’ll cover those in a later post. The summer greenhouse season isn’t all that important because we’re growing so much great stuff outside. Plus, our greenhouse turns into a shady porch and hangout spot in the summer with a 50% shade cloth, and we remove the racks that we add in the winter to increase growing space. The fall greenhouse season has not been fully explored. The greenhouse starts for the summer outdoor garden I will cover somewhere separately, because these will be transplanted outside the greenhouse after the last frost.

Here’s a chart of the first year of greenhouse operation, beginning in March 2013 up to April 2014. Open circles are the plant date, and I’ve shaded the regions of the calendar by the planting seasons above. This diagram shows how long it takes various plants to grow to maturity and harvestability. This diagram only shows the true successes, not the failures or the hot peppers, which only recently turned from a failure to a success (more on that below).

Heart of Winter Successes and Failures

The seeds were planted in flats and kept in our house (not the greenhouse) until after germination and when the plants just looked hardy enough to me to withstand cold temperatures. Our house is not very warm (during this time of year, 60-70 degrees) but the flats were in a sunny, south-facing window. I did not use warming mats. In general, seed germination in the house was not a problem. After about January, we tried germinating a few things directly in the greenhouse pots and planters, with mixed success.
Starting seeds in the house, not the greenhouse.
Lettuce, beet, and radish sprouts.

A table of planting dates, harvesting dates, and comments is shown below, with further detailed discussion of each of the individual plants below that. Note that while I’ll be discussing kale and chard here, under the heart of winter plantings, those were holdouts (well established) from a previous spring planting. I suspect that kale and chard can be planted anytime during the year and do JUST FINE. Similarly, one of the basils was a summer-growing transplant that we just moved into the greenhouse for the winter. Our one attempt to plant new basil in the heart of winter was a failure.

Details for individual plants are given below. 


We had great success with beets planted in March 2013 (right before the warm summer growing season) and also in December 2013 (during the heart of winter). The only problem with our beets was planting them too close together in a planter, which definitely stunted their growth when compared with beets planted randomly (and sparsely) in other planters. Heck, we plant everything too densely; that’s kind of our signature style.
Beets (and a few radishes).
Beets (right foreground), densely planted.
As for eating the beets, Aaron likes them raw, grated into salads, but I find the taste unpleasantly dirty. I like beets much better roasted, and a common winter dish that Aaron makes is root vegetables roasted in the Dutch oven on top of our wood stove. They carmelize nicely and taste delish.


The broccoli was only a fair success. It grew well and produced florets, but I wouldn’t call it “vigorously” successful (note: I have not grown this variety before, so I have nothing to compare it to). Most likely it felt cramped by being too densely planted in a small rectangular planter box. In the planters, it may have done better. This variety (calabrese) does not make large bunches of broccoli florets, but instead produces lots of side shoots. The leaves, shoots, and florets are great in stir-fries.

Chard and Kale

The chard and kale were planted long before the winter, in March 2013, and flourished through the summer in the shady greenroom. They likewise flourished through the heart of winter in the sunny greenroom. Is it even possible to kill this stuff?




The leeks struggled to thrive, looking like scrawny stalks of grass for quite a while. When the days lengthened and the temperatures climbed, by around February (check), the leeks began to look much more robust and started to look more like the size of green onions. They are also probably planted too densely to grow huge and thrive (same old story). We’ve been picking and cooking them young to help thin out the pot. Leek is great in miso soup instead of green onions.


Lettuce is an obvious success story for any winter greenhouse. It thrived. We tend to plant “salad mix” seed packets in the rectangular planters shown below. It takes about 1/3 to 1/4 of a planter to make large dinner salads for 2, and we just mow down that portion of the planter. By the time we get back around to that planter, it’s grown back. We have salads for dinner at least 2 times per week all winter long on our lettuce. We’ve been doing this since long before the greenroom was built: with two rectangular planters in our sunny south-facing windows, we could probably sustain 1 large dinner salad per week from our greens alone for months at a time.
This is a lettuce planter that's been half shorn for a salad. The
lettuce grows back at about the pace we eat dinner salads with
two lettuce planters of this size.

Hot Peppers

This was a failure story that turned into a success story and continues to astonish. I planted Hungarian Hot Wax peppers in small pots in the greenhouse in November 2013 after the Thai hot peppers planted a month earlier failed to take off. The little plantlings sat there, about 3 inches tall with just a few leaves, from December through February. Suddenly, it was as if a switch turned on, and the two little plants we’d kept alive all winter suddenly started growing. In March, they put on flowers. It is now early May and it looks like we’ll be harvesting our first hot peppers by the middle or end of May.
Peppers in May.

The lesson here is to go ahead and plant in February, because they won’t do much during the heart of winter but they will take off as soon as the conditions are right, and we’ll be harvesting hot peppers long before the summer crops.


The biggest success of our greenhouse; we may become radish farmers. Fortunately, we like them both raw (in salads) and pickled. The radishes grew happily through the heart of winter, with plantings in October 2013, December 2013, January 2014, and February 2014. We enjoyed the “Cherry Belle” variety, which grew quickly and formed nice round radishes the size of large gumballs. Another variety (“Dragon”), planted in February 2014, has been much slower to grow to maturity, so I can’t comment on the success of those yet. They should form larger, carrot-sized radishes. Next year, I’ll try other varieties during the heart of winter, but “Cherry Belle” is a sure winner.


The greenhouse tomato was actually a volunteer from our compost, and we have no idea what variety it was. The pointy-ended fruit look like a Roma tomato, or like a sort of pointy variety we grew a few years back, but the tomatoes are very small. They may be stunted because of the greenhouse conditions, but the plant itself grew humongous and took over a whole planter.
Huge volunteer tomato plant.
Tomato flowers in the greenhouse on a snowy night.
Aaron was never a fan of growing tomatoes in the greenhouse – he says they don’t compare to summer tomatoes in flavor, and we have tons and tons of summer tomatoes frozen in the freezer to eat during the winter. I thought these little tomatoes were a quite passable tasty little bite of summer when you least expect it, and all our friends who tried them thought they were delicious, too. However, the quantity we grew for the space the plant took up was a little disappointing. I would definitely try to buy a greenhouse tomato variety next time. Eventually, the massive plant fell over (it outgrew its paltry cage) and we cut it down. I was curious to see if the tomatoes were bigger and better in the summer, but we never had the chance. It will be hard to convince Aaron to grow tomatoes again, but YOU should do it. It works great!
Greenhouse tomatoes, May 4, 2014.

Growing Failures

Basil, Brussels sprouts, cucumbers, okra, parsley, peas, and thyme all failed on us. That doesn’t mean they’re not possible for heart of winter growing, only that something went wrong this time. (Some of these, like cucumber and okra, probably are, in fact, unsuitable, but I had to try.) Some of the plants that were failures as well as semi-successes, like the Brussels sprouts, hot peppers, and leeks, were incredibly slow-growing until January/February, and then they took off. The cucumbers and okra sprouted nicely, but the little plants never developed above a few inches tall, so eventually I let those die. The likely causes of failure (or very slow growth) were length of daylight, temperature, and pests. I don’t think water (too much or too little) was a primary factor in any of the failures, but I could be wrong. There may be other unknown causes of failure (e.g., bad seeds, soil nutrients or texture).
The Brussels sprouts (far right of overcrowded planter)
are finally beginning to grow after staying stunted all
winter. May 17, 2014.

Length of Day
The growing failures may have been caused by temperature or by hours of daylight. Here’s a graph of the number of hours of daylight near our location, along with the time of sunrise and sunset (note the one-hour drop for daylight savings time!):

You can see the hours of daylight (orange line) ranging from under 10 to over 14 as the year progresses. When I planted the hot peppers in November, the hours of daylight were minimal, at about 10, and that includes dusk and twilight where the sunlight is extremely indirect. In other words, just because the graph shows 10 hours of daylight, in reality the hours of direct sunlight is far fewer.
The greenhouse at night. (We don't use grow lights.)

The temperature was a problem, too. Okra, for example, needs warmth. Peppers thrive with daytime temps above 80, and nighttime temps above 60-70. I think the nighttime temps may have been the clincher because daytime temps were generally well above 80 degrees F in the greenhouse. Nighttime temps were regularly just above freezing, kept above the critical point by an electric heater that turned on at 35 degrees F. Yearly temperature data are coming soon.

Being hot and humid, greenhouses are notoriously rampant with pest issues, and I suspect this will be a frequent battle. Our greenhouse was struck by a cabbage looper caterpillar/moth in December. The cabbage looper attacked a few of the leafy greens – lettuce, radish greens, kale – and, most sadly, the young pea shoots. The pest makes its presence known by little black poops on the leaves (I should have gotten a picture of that, sorry). The little bastards were pretty easy to find and kill by hand, but they are green so they blend in well and we never got a good handle on them by manually picking them out of the leaves. Our usual go-to for organic pest management, a diluted solution of Neem oil, was ineffective. Finally, I got some advice from a local nursery and went with Thuricide, an organic pest control method that only works for specific bugs. Thankfully, it did the trick almost immediately, but not before we lost all of our pea sprouts.
Cabbage looper. Killed by Thuricide.

In April, a fine, silvery webbing appeared around the chard, with little reddish dots in it (spider mites). A spray of the diluted Neem oil solution once a day for 4 days took care of the problem (with just a single application, the mites returned).
Spider mites, killed with multiple applications of diluted Neem oil.

We had one more greenhouse pest problem. Note that some of the failures in the table above are marked with the comment, “mangled by cat!” This was a hilariously unanticipated problem: we didn’t realize that the long, rectangular planters looked an awful lot like a litter box. The cat spends plenty of time in the greenroom (in fact, she thinks we built it for her) and naturally she was pawing around in the rectangular planters until we figured out the problem and chicken-wired off the lower rack of plants to protect it from the feline.
We have to enclose the bottom-row plants with
chicken wire to keep the cat out when the plants
are little.
Why, I would NEVER use a planter as a litter
box and I resent the implication.