Raising cacti and succulents from seed

Books on cacti and succulents usually include a chapter on raising plants from seed. The directions are often intimidatingly elaborate, suggesting that it is a difficult art, requiring expensive supplies and many years to learn. However, the majority of cacti and succulents are no more difficult to start from seed than marigolds or impatiens. If you can grow your tomato plants from seed, you can grow Rebutias and Agaves. (There are some difficult genera, but they are beyond the scope of this article.)
[Disclaimer: I am not an expert. The procedures I describe work well for me, but other seed freaks get equally good results using very different systems. If you think you have a better technique, you probably do.]

Supplies


Procedure

Label the pots. I usually write the information on the side of the pot with a paint pen (magic markers and sharpies fade after several months). Fill the pots with the cactus mix up to about 3/4" to 1/2" from the rim and tap the pot on the table top to settle the contents. In the past I often used a seed-starting mix for the top half-inch, but I seldom do anymore; you might get slightly better germination, but you also get fungus gnats.
Distribute the seeds evenly on the surface of the starting mix. Avoid putting more than about 20 seeds in one pot, even if they are as fine as dust, unless you know that the seed has low viability. Press larger seeds gently into the mix with you finger. Don't cover the seeds unless you know that a particular variety needs dark to germinate; succulents often need light to germinate.
Water the seed pots from the bottom by filling the tub with about 1-1/2" of water and placing the pots in the water until the surface of the soil is wet. You can use a disinfectant labeled for use with seeds to lessen the danger of damping-off, but this usually isn't crucial. Drain excess water from the pots by placing them on old newspapers or paper towels for several minutes, then put the pots in a warm spot out of direct sunlight. Under flourescent lights works very well. Cover them with plexiglass or put them in ziplock bags to maintain humidity.

Germination and beyond

The majority of cacti and succulents germinate from 3 days to 2 weeks after planting. A few days after the first sprouts emerge slide the cover a bit or open the bag so that seedlings get a little fresh air. A few days after that remove the cover entirely.
Keep the seed pot moist at all times for the first few weeks or months after germination. As the seedlings grow gradually let them get dryer between waterings, but avoid letting the pot dry out completely.
Don't be in a rush to prick the seedlings out individually. Wait until they are obviously crowded; this can take from 3 months to 3 years, depending on the species. The average is about one year.

Miscellaneous notes

Most seeds can be started at any time of the year if you can supply the necessary light and temperature. A soil-heating cable, available at many nurseries, can supply warm temperatures in winter.
Some seeds, particularly those of stapeliads, are often contaminated by fungus spores. If this is a concern, soak the seeds for a few minutes in a solution of one part Clorox to five parts water and rinse in plain water before planting. This is rarely necessary with cactus and mesemb seed.
Stapeliad seed germinates better if it is covered with 1/8"-1 /4" of potting mix.
Extremely fine seeds, such as those of Parodia and Strombocactus, are frequently said to be difficult. Actually, they are usually quite easy. The only difference in my technique is to leave the cover on for a few months after germination until the seedlings have reached 1/4" or so in diameter. (Tiny-seeded mesembs usually do not need this treatment; although the cotyledons may be initially microscopic, they grow amazing fast for their first few weeks.)

-Don McClane


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