Those of you who are familiar with starting cacti from seed may ignore these directions. Here are some tips for those of you who are just starting out growing cacti from seed. You need to use full spectrum grow lights or a good greenhouse. You can’t just germinate them on a windowsill in an apartment–they need bright light and very warm temperatures for germination and growth!
For starters, you can buy cactus mix at the nursery supply store, but most of us make our own. Here’s the common recipe: 50% white pumice, 25% coarse, sharp sand, and 25% organic matter such as coir or compost. Mix thoroughly and inoculate with a handful of cactus mix taken from around growing cacti–this will provide bacterial/fungal substrate that supports the growth of healthy cacti. Use gallon pots or smaller. Fill to 1/2 inch from rim with your cactus mix, then provide a thin (1/4 inch) layer of sifted mix as a seedbed.
To make the sifted mix, run your cactus mix through a 1/8 inch screen. Sprinkle seed on surface and mist or water by setting pot in a bowl of water. Do not dislodge seeds or seedlings by rambunctious watering–its counterproductive. Many growers stretch plastic wrap over the top of the pot to create a mini-greenhouse effect for germination, then remove the plastic once the seedlings are up and going.
Set the pot in the light greenhouse or below full-spectrum grow lights. Optimal temperature is 70 to 90 degrees F. Germination is dependent on temperature, light, moon phase and the species you’re working with, but generally occurs between 1 and 5 weeks after planting. If the seeds do not germinate, allow the pot to completely dry out, then start over. This sometimes jump starts the process.
Once the seedlings appear, keep them propped up with pieces of pumice or gravel. Remove plastic wrap, but keep evenly watered for the first 6 months. After that, during the summer, water every 3 to 5 days, allowing the surface to dry between waterings. Water not at all or very infrequently during the winter. Many growers allow their cacti to grow closely together for the first year or two, then transplant to single pots once they have attained sufficient size to be readily handled. That’s it in a nutshell.
2 thoughts on “How to Start Cacti from Seed”
Purchased the trichocereus pervanius seeds from the website and had 100% germaination even after they had been cold stored for a little while. I used a heating mat and had them bright indirect light from the leds I have. Germination was within 3 weeks. However, I am curious on the seeds you collected from Peru, would you have any additional information about the plants that you collected from?
Thank you for all you do!
Cacti such as this, as you know, are available from strictly medicinal seeds only by mail-order. I am pleased that you know how to germinate cacti seeds and happy for you that these have panned out. We have collections of the various species and strive to keep them true to type. Yes, Peruvianus is originally from Peru. Please understand that cacti are obligate outcrossers–flowers must be pollinated by a similar type from different parentage. This is challenging due to the fact that most people clone cacti. That is why the seeds we sent you are so very valuable, and also why they will demonstrate some variability of form. It is not only the nature of the beast, it is. . . necessary. richo