Growing cacti from seeds is pretty straightforward. Usually, the mixed seed packs you buy in regular stores (or the cheap ones you find online) are hardy and fast growing. Perfect if this is your first cactus-growing experience. Keep in mind that there are dozens of ways to do this. This is just what worked for me.
Germinating the seeds
- Buy some coarse sand, pumice or turface and mix it 2:1 with peat. Some
types of cactus need an even grittier mix (my Astrophytum asterias and
A. myriostigma would have benefitted from that), but this is pretty
standard for most types of cactus. Use a small pot with drainage holes.
- Moisten the soil. You can now choose to nuke it in the microwave or leave it as
it is. Nuking it will decrease the chance of damping off, mold and
- Sprinkle the seeds on the surface of the moistened soil and bag the pot. Use a transparent plastic bag or cling wrap.
- Place the pot under grow lights or in a western or eastern window and wait.
Don’t place them in direct sunlight. They should germinate within 1 week
if the seeds are fresh.
- When the seeds have germinated, leave the
seedlings in the bag for the next couple of months. The seedlings
grow their first baby spines inside the bag in 100% humidity.
- After a couple of months, remove the bag. I’ve had success with just removing
it entirely, but others do it gradually by poking holes in the bag.
Keep the soil constantly lightly moist for the first 3-4 months. When the seedlings
are half a centimeter in diameter and covered in spines, they can easily handle a couple of days with crispy dry soil until you water again. A year after germination you can water them like adult plants,
once every 2 weeks to once a month depending on the type you’re growing
and the soil they’re in.
Keep your seedlings out of direct light from germination to approx. 6 months – 1 year after germination depending on how big they are and the climate you live in.
Give them more light if they stretch and turn pale green. If they turn red or brown, move them further into the shade. I start my seedlings under grow lights and gradually move them to a southern window with 7-8 hours of direct/filtered light 6-7 months after germination.
If you’re interested in seeing how my cactus seedlings are doing now, here’s a collection of all blog posts from germination to the latest post about these guys.