Cactus and Tender Succulents forum: Starting cacti from seed help

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Name: Diane Mckee
Florida (Zone 10a)
Sep 22, 2016 3:11 PM CST
Hi everyone. I've just decided to try starting cacti and succulents from seed. I've had good success working with cuttings and leaves, but I'm interested in taking the next step into seed germination. I know it takes a while but I like a challenge. I've already hit YouTube and watched a bunch of videos. I'm going to sterilize my pots and soil, which is what I do for any seed starting process. I've ordered Dragon fruit cactus ( Hylocereus undatus) and a package of various echinocactus. Total opposites but let's see how they do. Please. Any advise?
Name: Baja
Baja California (Zone 11b)
Cactus and Succulents Seed Starter Foliage Fan Xeriscape Container Gardener Hummingbirder
Native Plants and Wildflowers Garden Photography Region: Mexico Plant Identifier Forum moderator Plant Database Moderator
Sep 22, 2016 8:51 PM CST


My approach depends on the size of the seed. Around poppy seed size and smaller, you need to leave the container under plastic, or in a plastic baggie, whatever homemade solution will do... for months. The larger seeds you can lift the lid earlier on, with the unveiling of the first seed leaves. But until the point when the plant is succulent enough to start holding some water, I prefer to leave germinating seeds in 100% humidity. After taking off the lid, I like to mist a bit daily to help them adjust in the beginning.

My seed starting mix is just like my regular growing mix (50% pumice, 25% coco fiber, 25% potting soil) but I use a finer grade of pumice and always filter out the bigger chunks from the potting soil. You can cover the seed with a thin layer of fine pumice, basically start your seeds under top dressing, if you like. The really fine seeds (like Echeverias) you definitely don't want to cover at all.

With the fine seeds there is an increasing risk of contamination. If you want you can cook the soil in the pot (be sure to saturate it with clean water first, and keep it covered until sowing, after it cools). I do a microwave thing where I cook for 20 seconds, wait 2 minutes, and repeat... usually 10-12 times, and you can tell when it's cooking because there's a sweet soily odor in the air. Smiling

I leave most germinating seeds on a N-facing windowsill which only gets hit by the sun for part of the year, and only in the morning. My hunch is that a daily natural light cycle may be helpful. After seeds germinate (the bigger ones anyway) they tend to lean toward the light in this directional, low-light situation. For that reason I like to rotate them regularly so they point away from the the light, or intermittently whenever I remember. From there on it's a process of gradually increasing the light (S facing windows) and decreasing the amount of babying (misting or whatever) over the course of however many years it takes for them to become tough and independent.

Bottom watering is useful when you don't want to disturb very small seedlings. A falling drop of water can be disastrous for tiny plants at the beginning. So you can place the container, typically still covered at this point, inside a clean plate full of clean water, to a depth of half an inch maybe, and leave it sitting there for 20 minutes or whatever, and that allows the moisture to percolate up to the roots.

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