SunCalc: Taking the guess-work out of gardening

In my previous life as a chef, I would often scorn cooks using meat thermometers to test whether a steak was ready. A simple finger test could instantly tell you what you needed to know but rather than train themselves in this art, they relied on science to alleviate the guess-work.

Well, it seems that the guess-work is now being taken out of gardening too. The SunCalc, an instrument to measure sunlight in the garden is probably one of the most intuitive tools that gardeners can use. As we all have multi-micro climates within our gardens, the SunCalc can accurately inform you of what level of sunlight you can expect in each zone.

And this is great because most plants that are sold, whether as seed or potted plants, are described by their optimal sun requirements. Full sun, part sun, part shade and full shade are options that we live with and need to know in order for our plants to have the best shot at success.

C.C from Coastal CA Gardening used her SunCalc to find a new full-sun zone for her tomato plants while the Garden Keeper at A Garden by the Ruins near Narberth was informed last year that one of her planting areas was not full-sun as she expected but instead was only partial sun. This is quite liberating information, especially if you’ve found that plants have consistently struggled to grow even after all the fertiliser and soil improvements you’ve added.

The SunCalc can only be used in the summer months to get an optimum reading. However I would suspect that with the height of the sun changing in winter it may pay to re-check your zones on a sunny day to see whether they alter.

I’m not sure where you can buy these as I’ve never seen them in the shops and don’t stock them. If you do know of a retailer who carries these and a current price, it would be helpful to share with others so feel free to comment. is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Additionally, we participates in various other affiliate programs, and we sometimes get a commission through purchases made through our links.