Where it has space to grow, classic lemon bottlebrush that was so popular in the 1960’s is still a practical and resilient large shrub, and is happy to bloom with bright scarlet flowers as long as the weather is warm. It is resistant to most diseases and pests, and once established, survives on annual rainfall. Its main problem is that it simply gets too big for many situations.
Dwarf bottlebrush, Callistemon ‘Little John’, is more often a better fit, although it has a very different personality. It is short and dense, and spreads more laterally than upright. Mature plants are only about three or four feet tall, and maybe twice as wide. The smaller leaves are somewhat grayish. The distinctive bottlebrush flowers are a slightly darker shade of purplish red.
Even though established plants do not need much water at all, regular (but not necessarily generous) watering promotes bloom and growth. However, excessive watering can be lethal. Full sun exposure is best. A bit of light shade should be no problem. Dwarf bottlebrush makes a nice low informal (unshorn) hedge. Flowers attract bees and hummingbirds.
Tony Tomeo 
I like the dwarf form myself. Outside the front gate is a mature bottlebrush tree – about four metres high. Gets quite bushy but does not get a lot of flowers.
I’ve got a dwarf bottlebrush, in the backyard, but it’s still early days as far as growth goes. I’m going to move it soon to a dedicated Aussie native bed, next to a pink flowering Grevillea that is already established.
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Bottlebrush are not an easy topic here. They have such a stigma because of the lemon bottlebrush, Callistemon citrinus, that was too common decades ago. It is a shame because bottlebrush is so well suited to the local climates, and needs no supplemental irrigation once established.
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I have bottlebrush as well, but it gets browned by frosts every year. By the time it really recovers, it might or might not bloom. Really weird because it is in an area where it should be protected. My neighbor has his right in the open & it blooms every year.
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The specimen that is more exposed to the weather might also be more exposed to warming sunlight, or in a spot that gets warmed by sunlight during the day. It is difficult to say why marginal plants perform well in spots where they are not expected to.
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I have the Weeping Bottlebrush tree and I love it. It attracts lots of birds and hummingbirds.
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That one is RAD, but still uncommon. A few mature specimens live on the embankments of the Santa Monica Freeway through Los Angles, but are out there where only the flowers are visible from a distance. They can be pruned up into such distinctively gnarly trees, with those softly swaying limber branches and blooms.
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We have a couple of weeping bottle brush plants. We have two other bushes with bottle brush style flowers… they are lovely plants/trees. I just wish mine were happier. Reading your notes above re overwatering is lethal, I wonder if I’ve been guilty of that.
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They all seem to be sensitive to that, although the common lemon bottlebrush, Callistemon citrinus, will tolerate regular watering for a long time.
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I’ve never grown any bottle brush plants, but I sure like to see them grown! They do well here, but apparently grow slowly
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The various specie and cultivars grow at different rates. The dwarf cultivars tend to be slower of course. Weeping bottlebrush can but out some long vigorous shoots.
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