Making the Greenhouse Weather Tight and Potting On Brassicas

Weatherproofing the Greenhouse

The greenhouse at the back of the office here is made from twinwall polycarbonate, similar stuff to that in a conservatory roof. The idea is that it will hold the heat in although it does reduce the light level compared with glass. A bit of a trade off with a benefit that it does not need any shading to prevent scorch in the summer.

The downside is that it needs really good ventilation in summer to avoid the temperature hitting boiling point. The solar powered fan will assist in that. The problem now is that there is a gap between the greenhouse and the wall on the west side and when the wind is east-west it whistles through the greenhouse.

I invested in a tube of expanding foam, which filled the gap in a couple of minutes although it cost ?6.49. Ouch! The benefit, however, is that the greenhouse is much warmer. At present it is just above freezing outside and inside the greenhouse it is about 15? C with the heater on half power. I may have to reduce it to a quarter power!

Just to make it clear, the greenhouse is not hermetically sealed. There is an air gap above the door and a fair amount of ventilation left where the roof meets the front. If there was no airflow the paraffin heater would exhaust the oxygen from the air and go out.

I do have a maximum and minimum thermometer in there so I can see how it performs overnight.

Moving around and transplanting

The brassicas have all germinated very well in the front bedroom and were starting to pull to the light so I moved them down into the greenhouse. I transplanted some to modules, 15 to a seed tray. The one thing I find really hard in growing is sowing little seeds, watching them pop out of their seedcase and then tenderly moving them along. Finally I chuck half of them into the compost bin because I always have spares. It’s nature’s way to produce many that a few might survive. That’s why you get 300 seeds in some packets.

The onions have yet to germinate so I’ve moved their trays up into the front bedroom where the temperature is stable around 13? so it may push them along. Having seen the temperature effect of the draughtproofing, I’m a lot happier about moving them back when they pop up.