A guide to azalea hybridization: how to cross-pollinate and grow azaleas from seed.

Evergreen azaleas are usually propagated through cuttings. By rooting shoots of a known cultivar, one can obtain new plants that are true to type. Because this is a form of asexual propagation, the genetics of the offspring is usually identical to the mother stock plant. In some cases, because of the sporting nature of the parent, the cuttings may differ from the parent.

When seeds are used to produce more azalea plants, the genetics of the seedlings are different from the parent. This means that the seedlings will not come true to type. Because most azalea culltivars are hybrids obtained from crossbreeding many different species, and because azaleas resist self-pollination, seedlings can be quite variable, especially with respect to their flowers.

This means that named cultivars are often exceptional seedlings that can be mass-produced through asexual propagation. While an azalea raised from seed can be quite mundane or even an ugly duck. One can only approach the quality of named varieties by raising a sufficient number of seedlings. The other side of the coin is that the only way to either improve exciting cultivars, or create new varieties that are just different, is by using sexual reproduction and growing from seed.

Even though the average seedling will be, well average, it may still be worth it to grow some seeds from your absolute favourite azalea. Just for fun and to see what the results are. A more advanced approach is to specifically select two parents, cross-breed them, and see how their genes mix. Likely, you will then hope for trait X from parent A and trait Y from parent B, which will likely result in some disappointments. In a professional breeding program, one may have a very specific breeding goal that can be evaluated. Say it is a long bloom period. And in your breeding, you only use parents with superior bloom time. And then, raising from seeds is just the first step. With the second step being having strict and clear selection criteria on those seedlings. In such a program, true progress may only be made after several generations of strict selection. The most ambitious approach, and probably not a realistic one, is to have a list of several traits, probably each only present in a handful of candidate parents, with the goal to combine all these desirable traits in one exceptional new seedling.

To make a cross we first need two azaleas that have just started to flower. One azalea will be the seed parent, the other azalea will provide the pollen. The flower is most ready to receive pollen about 4 days after it oepned, but pollen can be applied earlier. The stigma of a flower can often be shiny with a sticky mucus, but this depends on the weather and on the specific variety. Next, one collects stamens from the pollen parent. These can be pulled out one by one, including the filament, from the pollen parent azalea. Some varieties produce copious pollen in every single anther. But for many varieties, pollen may be sparse. The pollen will always be white in colour. So for varieties where the anthers are coloured, the presence of pollen will be quite conspicuous. Azalea flowers with have anthers with two pollen sacs, which will appear as two white dots. If the anthers themselves are white, they are not visible.

To make more pollen come out one should tap or finger flick against the filament. Repeating this until the two white dots fuse into a mass of pollen. Some pollen may fly out, but usually enough will remain to apply to the seed parent flower. Once there is enough visible pollen, touch the pollen end of the anther onto the stigma of the seed parent flower. Since the pollen is sticky, this should allow one to 'paint' the pollen onto the stigma. If the receiving stigma is covered with a lot of mucus, this may act as a glue that prevents the pollen from coming out of the anther. In that case, finger flick until a string of pollen hangs out of the anther, and apply this string of pollen to the stigma. Once enough mucus mixes with pollen, the stigma will no longer apply mucus to the anther of the pollen parent and block the pollen from coming out of the pollen sac. Sometimes, several stamen are needed to pollinate one flower. In rare cases, a variety produces so much pollen, one stamen can be used to pollinate more than one flower. If the pollen is brittle, it will not form a string that hangs out, but scatter away when finger flicking. In this case, applying the pollen to your finger, some other surface, or a pollination or make-up brush can be the solution.

When most flower seem to lack pollen, try to find the largest flowers on that variety of azalea. Some varieties will almost never produce pollen.Such varieties may be best used as seed parents when one really wants to cross-breed them.

Strict measures to prevent pollen contaminations likely are not necessary when just playing around and raising some seeds. But in the case of very specific breeding goals, it may be essential that the pollen parent is correct. For example when the pollen parent provides a recessive mutation to the F1 seedling, that will be expressed in the F2 seedling phenotype, being 100% sure about the pollen parent can become very important. The most effective approach is to make the cross indoors under a growing light, or inside a greenhouse where pollinators cannot enter. The first step to contamination-free cross-pollination would be to find an unopened flower on the seed parent and then to carefully remove the flower petals. Make sure to not damaging the stigma of the flower and to not release any pollen from the stamens. For example, pollen might stick to your fingers when pulling out the stamens. The unopened and now emasculated flower likely is not fully mature and receptive. A netted bag can be placed around the branch to keep out pollinators. The flower is most ready to receive pollen about 4 days after it oepned, but pollen can be applied earlier. The stigma of a flower can often be shiny with a sticky mucus.

The satsuki varieties do have some inherent advantages when it comes to bonsai. Some satsuki have small leaves and shorter internode growth. Furthermore, satsuki generally respond better to pruning than many other azalea varieties, producing more buds. Satsuki generally are more bushy and have slower growth, which can be advantages for bonsai. However, it is not actually true that satsuki azaleas were deliberately bred for their ability to grow trunks, though there are some varieties that are noted to have better characteristiscs for developing tapered trunks. Since it takes many decades to develop a massive trunk, varieties are adopted and becaome popular irregardless of their suitability for bulking up trunks. However, at some point in the future it may be considered that indeed a subset of satsuki were bred to be superior for this style of bonsai. It is very rare to find an evergreen azalea this a true species rather than a cultivated varieety, even in a botanical garden. So for bonsai, one would generally prefer satsuki azalea cultivars that are most suitable for bonsai. In this article I list the most famous ones.