UNITED STATES—Even without any of the five senses that we are outfitted with, plants are remarkably perceptive of the weather and the changing seasons. They know precisely what time of year it is because they know how long the sun is up. Their calendar is just as accurate as ours is. They also know that the weather has been getting progressively cooler through autumn, and that it rained a bit earlier.

New Zealand tea tree, torch lily, euryops daisy and many other plants from other temperate climates do not seem to care that they should not be blooming at this time of the year, if the weather is telling them otherwise. If the weather is warm enough during the day, even if it gets cool at night, these plants will bloom right up until things get really cold, even if some of their bloom gets frosted.

Saucer magnolia, lilac, apple and the many other plants from climates with cooler winters should know better than to bloom this time of year. Many bloom only once annually, so whatever blooms now will not bloom when it should next spring. Besides, the flowers that try to bloom now will bloom slowly, and probably be ruined by cool or rainy weather before they can develop completely.

Roses had a particularly weird year. They bloomed well and on schedule last spring, but then idled through much of summer, only to express a new interest in blooming now that they should be going dormant for winter! No one wants to prune them while they have more buds than they did in August. Fortunately for them, they bloom more than once annually, so should recover by spring.

The colorful foliage of sweetgum and Chinese pistache, as well as the observable weather, indicate that everything is more or less in order for this time of year. Autumn might have started out mild, but it had been even warmer in past years. It is impossible to say why some magnolia, lilac and apple are trying to bloom already. They each have such distinct personalities, and respond to so many different variables besides the obvious; daylength, temperature and humidity.

Highlight: New Zealand tea tree

With such an odd variety of flowers blooming out of season, it should be no surprise that New Zealand tea tree, Leptospermum scoparium, decided to join the party. It starts blooming in phases in spring, and continues into autumn, so it is not too terribly out of season. Besides, some varieties are known for spontaneous bloom phases at any time of year. Bloom can be pink, white or red.

The finely textured and aromatic evergreen foliage is slightly prickly to touch. Individual leaves are tiny and rather narrow, with pointed tips. Flowers are also tiny, but compensate with profusion. A few varieties have darker, almost bronzed foliage. A few varieties have fluffier double flowers (although the flowers are no wider than single flowers). The weight of bloom can cause limbs to sag.

Most garden varieties can reach the eaves. Larger varieties can eventually get to upstairs eaves. With minimal pruning, New Zealand tea tree is a colorful big shrub, with blooming stems from top to bottom. Alternatively, it can be an excellent small tree, with lower stems pruned away to expose the finely furrowed bark of the main trunks. It wants full sun, but not much else once established.