Should cactus seeds be covered in glass for indoor growth and put in full sun during germination? Should Mammoth Russian sunflower seeds have the greenhouse dome on top of them and be put in full sunlight during germination?
Cactus and Sunflower Germination
Certified GKH Gardening Expert
I would recommend not using a glass dome and full, direct sunlight together. The combination of the two would result in elevated temperatures under the dome that would likely kill the seeds. A glass dome in bright indirect light would be helpful, but not necessary to germination of either plant. Really, it is not so much about the light - most plants unless specified on the package do not need light to germinate. It is about the humidity and the heat. The glass dome would provide elevated levels of humidity and in indirect light would help increase the heat some.