for the Southampton BCSS meeting on Tuesday 7th May 2024

Carl Garnham's article is aimed mainly at seed raising:

• hysteresis
• “many thermostats on the market leave a very great deal to be desired”
• “Many seeds need a diurnal variation in temperature to germinate.”
• Heating pads and soil warming cables

Full article, including links to references and equipment: Thoughts on heating by Carl Garnham, SABG Newsletter no. 49 (August 2023)

1. Always keep greenhouse glass, inside and out, as scrupulously clean as is possible.

2. If any particular plant/species is associated with shade in habitat, think carefully about possible lighting levels habitat v. inside a UK greenhouse.

3. Within a UK greenhouse, in winter, with clean glass and bubble insulation in place, light levels and insolation will be a small fraction (10-20%?) of the level in winter, in habitat, in RSA.

4. Remove bubble-wrap insulation when not required, although it may be needed during the winter, the time of least natural daylight (insolation) in the UK.

5. Providing truly significant supplementary levels of growth-promoting lighting (PAR) beyond sunlight in a UK greenhouse is neither simple, nor cheap, more so if using anything but commercial horticultural designs and very much so in winter.

6. Stimulation of flowering/extending photoperiod does not require major levels of lighting.

7. Experiment, with winter photoperiod, lamps, reflectors and positioning of lamps, and perhaps colour of lighting – there is no data out there for any plant that we choose to grow, so far as I have been able to find. (Just a prompt – is the glaucous colour of some plants seen in nature, which is seldom seen in many plants in European cultivation, triggered by total insolation, or by high levels of just one colour? It would be comparatively easy to massively boost a narrow band of colour if that was all that the LED produced (assuming that LEDs are available that produce that colour), which is what commercial horticultural lighting does.)

8. If anyone experiments, to come closest to understanding what is going on, a measurement device is needed; you cannot trust your eyes (a consequence of the amazing biological engineering that eyes represent)

Full article, including links to references and equipment: My first tinkering with artificial lighting for plant growth by Carl Garnham, SABG Newsletter no. 50 (March 2024)

In an earlier SABG Newsletter, there is an article on cat litter as a potting medium.

Add a link to the article.