Greenhouse

The greenhouse seemed like a good idea at the time, and I'm still glad to have it. Unfortunately it is not performing its intended function, to provided a good growing environment for young vegetable plants until frost is no longer a threat, as well as we had hoped.

It makes a great solarium when the March sun heats it up in the afternoon, but during April and May the sun is too intense and the temperature can soar past where even butternut squash are comfortable.  Opening windows at either end usually doesn't sufficiently reduce the heat, especially if the day is calm.  I protect the plants by stacking water-filled plastic juice bottles in front of the them to absorb some of the sunlight.  The chloroplasts don't get as much direct light, but they also don't get cooked.  It's surprising to me how little of this blazing heat is retained overnight.  The min-max thermometer shows that temperature inside the greenhouse overnight has been similar to the reported low.  If the forecasted low is 2C or less, I carry everything into the house for the night, which is an effort I'd like to avoid, especially considering I might forget until after dark.  Some protection is afforded by leaving the water bottles in place and covering the whole assembly with a sheet.  The solar heat absorbed during the day radiates into the enclosed space and saves a few, but only a few, maybe three, degrees.

 Barry worked very hard on this greenhouse, scavenging windows from back alleys (this is quite acceptable in Lethbridge), digging into the tough clay substrate, setting huge posts in concrete, then framing, roofing, glazing, and insulating the whole structure.  It must not become just a spot to store lawn chairs and gardening supplies.  Proposed amendments include replacing the glass portion of the roof with shingles and adding some insulation, getting a solar powered fan to improve air circulation when wind is not enough, and painting the floor (large concrete paving stones) black to better absorb solar heat.  It could use some more thermal mass, too, though I don't know what to use, other than more water bottles.

That all said, the greenhouse is still much appreciated.  It makes possible a warm, windless place to do messy potting up work in early spring.   And it does provide opportunity for the plants to get a bit of hardening off (aka tough love for seedlings) so that temperatures out of the range of 14-17 are not a shock when they are transplanted.

 More tough love was applied this week in the form of culling.  Into each starter pellet we had dropped two seeds.  Most seeds are expected to germinate, and do so, but there is the odd dud.   Only one individual admitted per transplant site, though.  Thus, when two tomato seeds germinate, one eventually has to meet a premature end; there is no separating the roots.  With scissors in hand, I decide which one has better prospects - the one which is bigger, or leafier, or more upright - and snip the stem of the other.  It feels like a waste of a plant, but I know how difficult it is to maintain the vines of just one plant at a stake, and the longer the plant is allowed to grow, the more of a waste it will seem.  The first one is the hardest, not exactly Sophie's choice, but hard; the process rapidly gets easier.  Some of the pairs had started twisting around each other for support and the survivor was distinctly wobbly.  One could get anthropomorphic about it - the one left alive is reeling in grief at the loss of its partner (and some might say that's not even anthropomorphism, but just the way plants are) - but that would be to risk caring too much about their well-being.