Cactus Mammillaria

The genus Mammillaria is one of the largest in the cactus family (Cactaceae), with currently 171 known species and varieties recognized. Most of the mammillarias are native to Mexico, but some come from the southwest USA, the Caribbean, Colombia, Venezuela, Guatemala and Honduras. The common name "pincushion cactus" refers to this and the closely related genus Escobaria.

The first species was described by Carolus Linnaeus as Cactus mammillaris in 1753, deriving its name from Latin mammilla, "nipple", referring to the tubercles that are among the distinctive features of the genus. In 1812, the cactus specialist Adrian Haworth described the genus Mammillaria to contain this and related species. Numerous species are commonly known as nipple cactus, fishhook cactus or pincushion though such terms may also be used for related taxa, particularly Escobaria.

Growing Cactus from seeds is not very difficult, even if it takes patience and purpose. All attempts cacti from seeds is to haphazardly rarely result in mature plants. And so it is in nature. Many thousands of seeds are produced reached for each individual plant maturity. Fortunately, we were able to significantly improve these odds by following a few best practices. This article is intended as a general overview of seed and I am not suggesting that the method described here is the only way to do this nor can I say that it is better than other methods. Rather, this is only one method, which has produced positive results. It is my goal to encourage others cactus enthusiasts try their own hand at seed breeding. I myself have learned that fails down from more experienced breeders after miserably to do it on my own methods described. I still do not consider myself an expert on the subject and in this sense, should not be discouraged if you do not get it right the first time.

Getting Started

The first thing we need to sow seeds is some pots. Seedlings are very small and grow fairly slowly, so 2inch pots are sufficient. There seems to be an unwritten philosophy among seed growers that the cheaper the seed growing setup the better. This is not to skimp on meeting the needs of the seedlings, but to do utilize existing materials as much as possible. One of the ways to raise seeds on the cheap is to reuse pots.

Another way is to use leftover food containers or other similar items. In this case, I had a number of small plastic tubs that mealworms come in for feeding my reptiles. These containers did not have holes in the bottom, so I drilled some. As we will see later, the seedlings will be in 100% humidity and therefore drainage holes are useless. I added them because I wanted to be able to keep the seedlings growing in the same pot as long as possible to avoid early transplanting risks. If I were to transplant them immediately after moving them to an open air environment, then I would have skipped the holes.

When reusing pots, it is important to clean them to avoid potential fungus, algae, or other pests that may quickly kill delicate seedlings. Taking some precautions up front to prevent pests and disease is far easier than trying to fend off threats after germination. Cactus seedlings are especially sensitive when small and fungicides or insecticides can kill or weaken the cactus seedlings. Some people add a mild fungicide when sowing, but proper sterilization should eliminate the need for this. To clean the pots, I soaked them in bleach water for a good while and then rinsed them thoroughly

Next, we need to prepare some soil. I use my standard cactus soil mix and sift out the larger pieces. You can read about cactus soil mixes on this articles . I found a child's beach toy to be a perfect tool for this job. Of course, the soil must be dry in order to sift it. After the large parts are removed, I wet the soil so that it is damp throughout, but not soggy. Then the soil goes into the microwave for 4-6 minutes depending on how much soil there is. This is to sterilize the soil and kill any potential threats to the seedlings. It is best to stop partway through and mix the soil. Be careful as it can be very hot in parts and cool in others. Some people bake the soil in an oven for the same purpose.

Again, using your typical soil mix won't work for every species, but should be fine on more common species. When you get into some of the more challenging species, your best bet is to seek out advice from other growers that have tried that same species. Some species are extremely slow and will be in the seedling environment for well past a year. Some species will not tolerate the same amount of organic material as others.

After the soil has cooled some, we are ready to fill our pots. It will cool even more as you do this. I use an empty pot as a scoop and fill the pots right to the top. Once filled, I tap the pot and smooth out the surface with my finger. This prevents the seeds from falling down any large gaps in the soil surface. Then I sprinkle the seeds evenly over the surface of the soil. In the picture below-right, I pointed out a couple of the seeds using red arrows. The green arrows are pointing to fertilizer. I like to use a time release fertilizer like Osomocote as it will slowly release as the seedlings grow. Note: This process can be a bit messy so I used a flat cardboard box as a work tray. When finished, I just dispose of the cardboard and clean-up is done.

Unless you are one of the few growers who don't care about names, it is critical that you carefully label the pots as you go. Seeds and seedlings can look very similar for the first few years. Even at maturity, some species are a challenge to ID properly without knowing the origins of the seeds. Melocactus are one example in particular, but there are many others. There are several ways you can go about this and most people put a tag in the pot with the full plant name and collection number if applicable. In my case, I numbered the pots on four sides. Then I entered the names with the corresponding number in a spreadsheet on my computer. In this way, I can easily update it with notes as germination occurs or when I transplant them later on. Often people keep track of the number of seeds sewn and monitor the germination rate for each one. I didn't do that this time, mostly because I forgot! 

After the seeds are in place, I take some of my sifted soil pinched between my fingers and sprinkle it over the seedlings until they are just covered. It is not necessary for the seeds to be covered, but helps to support them once they start to grow. Each species is different and some need light to germinate so consult the CactiForum if you are unsure about this. At this point, I take a spray bottle and give the plants a good soaking. The soil is already damp from our pre-microwave wetting and now I saturate it until the water just drips out the bottom. Be careful to use only a light spray for this or you might wash the seeds right out of the pot. 

For this article, I chose to use the "baggie method" which is a popular technique among growers worldwide. In this way, I place each pot of fresh-sown seeds in a ziplock baggie and seal it shut. This method has several benefits. It eliminates the need for watering as the moisture will condense inside the bag and soak back into the soil providing a constant moist environment for the seedlings. This kind of environment works best for most cactus seedlings despite the fact that it would quickly kill a mature cactus. A second benefit is that the sealed bag keeps out undesirables like fungus, gnats, or other pests. Even if you sterilize the soil and pots as we did earlier, if the pot is not sealed, many pests will find the warm/moist environment too good to pass up. And they will find the tender green cactus seedlings to feed on just an added bonus!

Seedlings will appreciate bright light, but will not do well in full sun. The sun is too strong for almost all seedlings and in the wild they usually start growing in the protection of a rock or other plant. With this caution in mind, placing the pots in a bright spot under a shelf in the greenhouse or in a window that gets sun for only part of the day is a good option. For even better control, however, artificial lighting is ideal. You can find more information on which lighting setup to use for seedlings at the end of the artificial lighting article. In my case, I used two lighting hoods that I already had for keeping reptiles with a compact florescent bulb in each one. For a propagator, I kept with cheap-seed-raising tradition and used a 10 gallon aquarium that I already had. I used a piece of stiff cardboard for a lid and cut holes in it for the light domes. Since the pots are in baggies, I do not have to worry about keeping the whole propagator humid or sealed up. Since the aquarium is clear glass, much of the light that should be going to the seedlings is escaping into the room. This was easily remedied by taping some white scrap paper around the outside of the tank to reflect the light back in.

I stuck a thermometer at one end and cut out the paper so that I could see it without opening the propagator. Most cactus seedlings like a temperature of 70F - 90F to germinate. This is a general statement, of course. Some species, such as Ferocactus may not germinate at the low end of that and you'll have to turn up the heat. Many people use a heating pad on the bottom for controlling temperature. If you do, be sure that you use it in conjunction with a thermostat or it could overheat quickly. 

Conclusion

Hopefully, in this brief article, I've been able to inspire you to give seed raising a try. As you see, there is a bit more effort required than just picking a cactus off the rack at a nursery. Some thought needs to go into the process along with taking the proper precautions. If at first you don't succeed, adjust your methods and give it another try. Start with common species and get advice from other growers. Finally, if you're on a tight budget, your frugal and innovative approach will be admired by even the most expert seed-sower.