Now that the dog days of summer are upon us some of you might be noticing buds starting to form on your coleus plants. While tendency to bloom varies from variety to variety, even the most bloom-resistant types of coleus may start to bud in the fall if they aren't regularly tip-pruned. Shorter days and cooler nights are the signal that the end is near and they had better get around to setting seed before the frost. Several factors can contribute to encouraging coleus to bloom. The first is the age of the plant. Coleus plants kept over from year to year in the greenhouse or in tropical climates will need to be pruned regularly to keep blooming tendencies at bay. Most people find that starting each year with fresh plants, purchased or from their own cuttings, is the best way to avoid age-related blooming. The second factor is stress. Temperature extremes, getting too dry, insect infestations, too much or too little light, and being pot bound could cause your plant to go into survival mode and try and set seed. The third factor is the variety of coleus you are growing. Seed-grown varieties are the most likely to bloom early, as are trailing varieties and some older varieties. The fourth factor is day-length and cool nights as mentioned earlier.
Whether or not to let your coleus bloom is a personal preference. Some folks just like the flowers! Coleus blooms are a spike of tiny flowers ranging in color from pale blue (almost white) to purple. They are attractive to butterflies and hummingbirds, which for some people is enough of a reason to let them form. If you have several you can cut them for an attractive blue bouquet. However, there are consequences to letting coleus bloom. As the plants mature and form bloom spikes the coleus can begin to look rangy and unkept. Occasional pruning can help control the size of the coleus and encourage branching for more bushy growth. In addition to blooming, coleus with very large branches can be susceptible to splitting and breaking, especially during wind storms or when being moved. Last, but not least, if you use a systemic insecticide in your soil please do not allow your coleus (or any other plant) to bloom. Butterflies and hummingbirds can be harmed by the nectar of flowers from plants grown in treated soil, and systemic insecticides have been linked to bee colony collapse disorder.
Many people will be timid about cutting their coleus at first, but coleus are very forgiving plants and benefit from being trimmed. They will grow back stronger and bushier than ever. Pruning or pinching coleus is easy! You can use pruners, scissors, or pinch them between your fingernails. If the coleus already has a bloom or a bud simply back down the stem to the first node with a set of leaves and trim just above them. Even if you can't see evidence of new leaf growth leaves will eventually sprout from the node. If you see tiny flower buds forming in the new growth trim back even farther. Occasionally a coleus will have gone too long without pruning and it will be difficult to find new growth without buds. If a coleus is in this condition and the plant is unsightly sometimes the best remedy is the compost bin. Taking cuttings from a coleus that has started to bloom out is usually futile since bloomy cuttings will make bloomy plants, if they root at all.
Some of the most beautiful coleus varieties will bloom as fall approaches. The trick is to regularly monitor your coleus and pinch back when needed to keep them looking great!
