Breeding...

Naturally occuring colors in bush mimulus are pale orange (known as buff), other orange shades, yellow, and red. Through hybridizing , other shades have been added, notably white and burgundy purple.

As an amateur breeder, I do not have the resources nor the space for a massive program. I cannot grow thousands of plants, nor can I manage tricky laboratory types of propagation. I am limited to simple crossing of prospective hybrid parents, and then growing the progeny from seed. In this I can be as methodical as I want, with numbers for each plant and cross, and keeping a detailed log.

Bush mimulus are not more widely grown because of their faults. The worst of these is that they become messy after bloom. This is doubtless the result of a long environmental history. In most of California our rains are mainly in the winter. By late summer conditions have become quite dry. Naturally, our native plants reflect the climate, growing and flowering in the spring and early summer, and drying back and going dormant in the late summer.

But garden conditions are different. We irrigate all year round, and we want our flowers to be attractive, and to bloom all year round as well. I think bush mimulus hold the potential for this, but it is a slow process to bring them to that point. In addition, I would like to be able to reproduce these hybrid plants by seed. Using cuttings for selected plants is easier, but using seeds is more convenient.

Another problem with bush mimulus is that they are sometimes temperamental to propagate in the nursery trade. Or temperamental to grow with garden soils and conditions. And breeders may hit a wall when excessive inbreeding weakens the plant or the seed production.

And so I am attemping to develope a very dwarf bush mimulus which blooms year round and remains neat, with a wide range of colors, and that tolerates garden conditions well. Toward this goal I have worked out a breeding program. So far, I have had mixed results. Eventually I plan to distribute some worthwhile varieties.

Durability...

In the more than twenty years I have been growing bush mimulus I have noticed that some varieties survive much better than others. As I understand, bush mimulus are subject to a virus which can deform the leaves and flowers, or kill the plants. A virus such as this, or any disease or pest for that matter, is more likely to occur where there are many closely spaced plants of the same species. Bush mimulus are also somewhat susceptible to over watering and heavy soils. Some varieties, notably mimulus aurantiacus longiflorus calycinus appear to grow as bienniels under garden conditions (meaning they live for two years and then die).

I have found that in general, seedlings are less likely than cuttings to succumb to virus or whatever it is that causes some of my plants to die each year. Nursery purchased species and hybrids (which are usually grown from cuttings) are much more likely to succumb than any of the other plants.

Some varieties, especially those which originate naturally out of my immediate geographical area are more likely to die in the fall than the other ones, although there are exceptions.

At the same time I have found some varieties to be especially robust, and able to survive reliably year after year, even in their clones. I am convinced that heredity is the key factor in durability of bush mimulus. That is why seedlings may survive better than cuttings (there is a degree of selection in growing the sturdiest seedlings).

Durability (specifically the ability to survive year after year, and resistance to wilting from lack of water) is therefore one of the important qualities I am breeding into my hybrids. I might add that the only way to be certain about durability is to grow the plants for at least several years. Some breeders do not do this, and possibly miss the point of plant longevity as a result.