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bcss:page [14:21 02/05/2026] – [Notes on sensors etc.] Richard Whitebcss:page [22:26 28/09/2026] (current) – removed Richard White
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-**''[[https://rwhite.uk|rwhite.uk]]''** 
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-====== Notes for BCSS Southampton branch ====== 
- 
-===== Notes on sensors etc. ===== 
- 
-for the meeting on Tuesday 5th May 2026 
- 
-<WRAP colmedium> 
-=== Outline === 
- 
-  * Show an alcohol thermometer.  You might have one of these in your greenhouse.   
-    * More sophisticated ones can be digital (show one of mine) 
-    * You need to go into the greenhouse to read it.   
-    * It's no use if you are at work or away on holiday. 
-    * Or you might look at the weather forecast and hope it's correct. 
-  * Some sensors can be read remotely 
-    * Oregon Scientific uses radio waves to  
- 
- 
-=== Items to include === 
- 
-  * Sensors for temperature, humidity, light, CO<sub>2</sub>, soil moisture ... 
-    * Battery operated / USB-C power / mains power 
-    * Communication by wire (incl. I2C, QWIIK), Wi-Fi, Zigbee, ZWave 
-    * Remote services e.g. local weather reports, forecast, etc. (basically using other people's sensors) 
-  * Hub(s) to receive data 
-    * Data storage and display 
-  * Control incl. mains sockets 
-  * Demo (with IKEA mini greenhouse) 
-    * Laptop (and Raspberry Pi) both with Home Assistant 
-      * with Zigbee dongle(s) connecting to 
-        * temperature and light sensors 
-        * soil moisture sensor in a pot of compost 
-    * Display temperature changes 
-    * React to high or low value 
-    * Control a fan and lights 
-    * Large (Samsung) and 17" monitors for display 
-    * Internet using phone as Wi-Fi hotspot 
-      * to allow access to weather data 
-      * to present display on (this) website for view on mobiles at meeting 
-      * to serve readings, show dashboard and control devices from mobile phone 
- 
-=== Things to sort out and test === 
- 
-  * Test the Ohio Scientific display unit and remote sensor 
-  * Test the weather station and (? Zigbee) hub 
-  * Install Home Assistant on laptop 
-  * Choose a Raspberry Pi and install Home Assistant on it 
-  * Test 17" as well as Samsung 22" monitors on Crocus (and Raspberry Pi) 
-  * Use remote slide changer to make the laptop  
-    * change slide in presentation 
-    * move from one page to another on the web or in a Home Assistant dashboard 
-    * ditto for Raspberry Pi 
- 
-=== Things to bring === 
- 
-  * Thermometer (alcohol) from hall 
-  * Thermometer (digital, unconnected) from lounge 
-  * Ohio Scientific display unit and remote sensor 
-  * Large laptop (Crocus) with Samsung monitor 
-</WRAP> 
- 
-===== Notes on heating, lighting, etc. ===== 
- 
-for the meeting on Tuesday 7th May 2024 
- 
-==== Heating ==== 
- 
-Carl Garnham's article is aimed mainly at seed raising, i.e. heating small spaces rather than an entire greenhouse:  
- 
-  * 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:  [[https://sabg.uk/_media/newsletter:sabgnews49.pdf|Thoughts on heating]] by Carl Garnham, SABG Newsletter no. 49 (August 2023) 
- 
-==== Lighting ==== 
- 
-{{:bcss:rhipsalis_pachyptera.jpg?nolink&400 |}} 
- 
-Growers of South African bulbs probably get more worried about light levels than succulent growers, because the former plants tend to grow in winter.   
- 
-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:   
-[[https://sabg.uk/_media/newsletter:sabgnews50.pdf|My first tinkering with artificial lighting 
-for plant growth]] by Carl Garnham, SABG Newsletter no. 50 (March 2024) 
- 
-===== Composts etc. ===== 
- 
-In an earlier SABG Newsletter, there is an article on cat litter as a potting medium.   
- 
-FIXME Add a link to the article. 
- 
-