Growing Cactus from Seed
I don’t think we’ve ever gotten this question before on the blog. Lucky for you someone finally asked it. Thanks, Lauren!
Hello Cactus Jungle,
In the next month or so I am considering trying to grow some pincushion cactuses from seeds. Do you have any suggestions on the the type of soil or how I should set up the initial planting tray?
Several months ago I impulsively started growing some cactus seeds from a variety mixture (so I have no idea what they are officially). How many years does it take for more common cactus varieties to mature and how long should I wait before attempting to repot cactus seedlings?
Thank you for your time and I look forward to hearing from you.
We germinate cacti seed in our standard cactus and succulent soil. If it is rare or expensive seed we will sterilize the soil first by steaming it – moistening and putting in a microwave safe dish and heating until it hits 160 degrees. About six to seven minutes on high for a gallon of soil. We then let it cool with a tight cover on and then use it in our seedling trays.
We will scatter the seed on the surface and lightly mist. Then we top dress with a single layer of crushed horticultural charcoal, that we either smash with a hammer or run through a little electric chopper (Cuisinart) until it is like course sand. We mist that as well. Then we dome the seed tray and put under florescent lights that run 16 hours a day.
Most pincushion type cacti will germinate in just a week or two, other types can take months. Of course after germination is complete and they start getting some growth we ventilate the dome and lower the humidity, but they do need it fairly humid during germination and that first push of young growth. We usually leave the seedling in the germination tray until they are the size of large peas or small grapes. With some species that is 6 months; others it is a year or two.
The big trick on transplanting is to handle them very gently so they do not bruise and make them prone to infection. It helps to keep them dry for a week after transplant so any damage heals under dry condition.
Good luck and have fun!