Guest Author - Connie Krochmal
Though cacti and succulents are generally more resistant to insects and diseases than many other plants, it is sometimes necessary to use garden chemicals to control these problems. Chemicals are sometimes used for various other purposes as well. If you’re considering using chemicals, here are a few things to keep in mind.
The first step is to check the chemical label. Make sure that the target plant is listed on the label. Otherwise, the plant can suffer damage. For example, the leaves and other plant parts might experience injury. This is most likely to happen with insecticide sprays. However, it could occur with systemic pesticides that are added to the potting soil.
In addition, check to be sure the chemical is labeled for that particular plant pest. As an example, certain pesticides will kill mealybugs and scale insects, which are usually the most common pests on cacti and succulents.
If you decide to use a chemical, be sure that it will cause no harm to non-target animal species, such as wildlife, birds, fish, and so on. Some pesticides are very toxic to household pets. In some cases aquatic life can be harmed by pesticides. Obviously you don’t want to use these if you have ponds, water gardens, and other aquatic landscape features that could be affected by runoff from such chemicals. If the chemical is known harm animals of various sorts, this information will be listed on the pesticide label.
There are other types of garden chemicals that are sometimes used on cacti and succulents at commercial greenhouses. The cacti and succulents you purchase at garden centers and nurseries might have been treated with special chemicals, such as plant growth regulators (PGR). These act much like plant hormones and direct the plants to develop new shoots, branches, and/or flowers.
Greenhouse growers use the PGR’s for specific purposes. For example, a certain PGR might increase the number of shoots and flowers on Christmas cactus plants. This would easily explain why a newly purchased plant might have many more flowers than an older Christmas cactus that you have had around the house for several years.
In the case of the hardy hen-and-chicks (Sempervivum spp.) a PGR can prompt the plant to produce many more pups or offsets than it might ordinarily have if left to its own devices.
In the case of echeverias, the plants are very free flowering when they’re treated with a PGR. In addition, the plants will have a greater number of offsets.
The moss rose and the flowering purslane can also be affected by PGR’s that are used on greenhouse plants. The use of these chemicals leads to an increase in branching. It also results in a more compact, low growing plant.
Kalanchoes are a familiar flowering pot plant. When a PGR is used on these plant, this encourages lateral branching. It also affects the size of the different floral features.