Breeding Haworthia

By Harry Lewis of Living Desert Plants

In my last article, I discussed how one can go about propagating Haworthia, to create copies of a single desirable specimen. An interesting alternative to this is to cross breed two separate plants with desirable traits, to create offspring sharing the traits of both parents. To do this, one must learn to play “birds and the bees”...

Haworthia pollination

Pollinating Haworthia is an often far more rewarding alternative to tissue propagation. It is, however, a tad more difficult to get the hang of, as there are many variables that play a role in flowering.

The small and delicate flower of a Haworthia

Haworthia plants need a few years to mature enough to flower, with the fastest growers generally only experiencing their first flowering season after 3 years. Slow-growing species such as H. maughanii can take up to 5 years or more to flower. Some, such as H. marxii, can even take more than a decade!

In addition, flowering is highly dependent on the season, as Haworthia generally do not flower year-round. Many species have different flowering seasons as well. One might pick two specimens to cross, but never end up getting them to flower at the same time! My H. truncata tend to flower during the end of the warmer months leading up to fall, and my retusoid Haworthia (H. retusa, H. picta, and so on) tend to flower when it starts getting cooler leading in to winter at the end of fall. This means I won’t be able to cross them.

Haworthia are luckily neither exclusively male nor female. This makes it somewhat less complicated to find suitable plants for breeding, as they possess both the male and female reproductive organs in their flowers. The male reproductive organ is called the stamen, which carries the pollen, and the portion of the female reproductive organ that receives pollen is called the stigma.

For a beginner, I would suggest waiting until there are two plants in flower at the same time to try out this technique on them. You will probably not get an amazing first batch of seedlings, but it is worth building up the experience regardless. Note that most Haworthia can hybridize, so one does not necessarily need two plants of the same species to successfully pollinate. They are, however, not self-fertile, meaning you cannot pollinate two flowers that are on a single plant with each other.

A Haworthia transplanted in Ibaraki Akadama (small particles) flowering for the first time

There is only one tool I use to pollinate Haworthia, and it is surprisingly simple. Many breeders use a technique that involves removing the flower petals to access the reproductive organs of the flower, and while I have done this successfully, I believe it to be overly complicated and time consuming. For my technique, one only needs a toothpick, some tape, and a single hair from a paintbrush. Make sure it is a new and unused paintbrush, as you don’t want paint residue messing with this process!

Now we will play the part of the bee, so to speak. After taping the paintbrush hair to the toothpick, gently wiggle the hair around inside of the first flower. You will notice it has some yellow residue on it when you remove it again, and this is the pollen. Now do the same in the flower you want to pollinate, and then back again to the first flower. In this way you will pollinate both flowers. It’s as easy as that, and after a few days, the flower petals will close and in time fall off as well, revealing a green seed capsule underneath. This seed capsules takes 6-8 weeks to ripen, after which it pops open and releases the seeds. To prevent this, you can either tape closed each individual seed pod, or you can cover the flower stalk in some fine netting so it catches any escaping seeds. The material from hairnets designed for cooking is good for this.

Using the paintbrush hair to pollinate Haworthia

Sowing Haworthia seeds

Now it is time to sow the seeds. Germinating Haworthia for the first time is a trial-and-error process, so I would not suggest using valuable seed from impressive plants for your first attempt.

Haworthia seeds require warmer day temperatures and relatively cool night temperatures to germinate. As a general rule when sowing, the days should be around 25⁰C, and the nights should not go below 10⁰C or above 20⁰C. This means they cannot be sown in winter, as it is too cold. In the Western Cape of South Africa, which is a winter rainfall area, I sow my seeds from October until April. The latest I have sown and germinated Haworthia seed was mid-May, and those only barely managed to get going before the colder temperatures started.

The container you use for sowing does not need to be deep, as Haworthia roots do not grow excessively large until they are about two years old. If you are sowing a small batch, any small Bonsai pot is perfect. As Haworthia do not have strong roots initially, the mix you use needs to support the plants and keep them growing in the right direction. I use a mix of one-half 2-4mm crushed LECA, and one-half Professional Seedling Mix from Bonsai Tree. I soak the mix and let it drain out excess water before sowing. Make sure you fill the pot as close the top as possible, as seedlings seem to struggle if they are not sticking out from above the edge of the pot.

Once your mix is ready, you can finally sow your seeds. Do not spread the seeds out too much, as growing the seedlings close together will help them support each other. The seeds do not need to be covered with any soil. I cover mine with very fine pebbles to help with support and prevent the seedlings from being moved when I water them. Haworthia seeds also require high humidity to germinate, so cover the pot with plastic or place it in a ziploc bag. Make sure the plastic does not touch the seed or soil, as this will interfere with growth.

After 7-14 days, the seedlings will germinate. One week after this you can remove them from the plastic to prevent rot and fungus from forming. The seedlings can be lightly misted with water daily, preferably early morning or early evening, and should be kept well-shaded for the first two months. I suggest keeping them under 60-80% shade cloth. Make sure they do not get any direct sunlight, as they are sensitive at this stage. Once they get stronger, they can be slowly adjusted to the same amount of light as your adult plants (for adult Haworthia I use two layers of 40% shade cloth), and can be watered every other day. Haworthia seedlings grow slowly, and you can expect to be able to plant them in their own pots after about two years. Do not do this too early, however, as they tend to struggle to recover if planted out when they are too young.

Haworthia seedlings in a professional seedling mix from Bonsai Tree

Harry Lewis is a qualified nature conservationist, with a National Diploma in Nature Conservation from Cape Peninsula University of Technology, and an Advanced Diploma in the same field from the University of South Africa. Between 2015 and 2018, Harry worked with large carnivores, such as lions and leopards, but has now moved back to his hometown of Stellenbosch. He has always had a passion for everything nature, including succulents, and now runs Living Desert Plants, a small succulent nursery, from his home. He specializes in growing Haworthia, but also stocks a wide variety of mostly indigenous succulents.

To contact Harry Lewis you can call him on 0741951144, email harryLivingDesert(at)gmail.com and follow him here: www.facebook.com/LivingDesertPlants/