This winter I planted cactus seeds for the first time in an attempt to keep myself busy during the cactus dormancy period. I started out by planting them in plastic egg cartons. These have both a tray and domes over the separate egg compartments, which seemed perfect. I cut tiny holes into the individual compartments using nail scissors and ran some cactus soil through a fine-grained sieve and microwaved it. I mostly followed the instructions here: Raising cactus from seed
My seeds were from two sources: Uhlig Kakteen in Germany and I also had 3-year old seeds from cactusstore.com. I sowed about 10-20 seeds per cell.
First three months
This is a picture of my first batch taken 2 months in.
First batch of seeds 2 months after sowing.
The egg cartons are not perfectly sealed, so the air and soil do dry out, especially when placed on a heated surface. I ended up watering them every week. I did not use fertilizer in the first 3 months with my first batch, but I started used it right away on the other seedlings. Despite the warnings against overusing fertilizer I am yet to experience any signs of having used too much. I now use it in two thirds of the waterings although the suggested amount seems every other time and half-strength.
There was a lot of growth in the next month for some of the gymnos as well as some of the large cacti, especially the cardon (pachycereus pringlei) seedlings, which also had a 100% germination rate. I had sown copiapoa and weingartia seeds as well, but none of them germinated.
Five months in
I followed this first batch with 2 more, about 2 months later. This time I used freshly ordered seeds from cactusstore.com only, specifically: thelocactus, gymno, eriosyce and notocactus mix packs, copiapoa gigantea and mix. I attempted 2 types of acanthocalycium but despite some initial germination three months later none of them turned into viable plants. I also got a few packs of melocactus (almost 100% germination rate) and browningia hertigliana (none germinated).
Five months later, I repotted all the healthy-looking seedlings, now between 3 and 5 months old into larger, shared containers. By far the fastest growing plants are the cardons. They are also robust as practically all of them made it through.
I ended up with 4 such containers, two of them containing 10 to 20 of the larger seedlings each while the other two fitted 40 to 50 seedlings. They all seem to have plumped up after having been moved.
All in all, these first 3 batches resulted in surviving seedlings of the following: echinocactus, melocactus, thelocactus, gymnocalycium, carnegia gigantea, ferocactus, eriosyce and 3 notocactus seedlings.
I got two more batches sown in the meantime, this time using only small plastic containers in one case and small pots sealed in a ziploc in the other. The new seeds are mostly escobaria, astrophytums and pilosocereus variants (not easy to keep alive past the first month in my case) and seeds of a few rarer plants that I really like: discocactus, gymno denudatum and saglionis, corypantha poselgeriana, thelo riconensis, mamillaria schumannii. Will return with an update!
