The petunia is one of the most popular flowering annuals. There hundreds of varietiesin four categories: grandiflora, multiflora, milliflora and groundcover. The categories are based on flower size and growing habits. Petunias can be planted in the garden or make great container plants. Grandiflora have the largest flowers and can cascade, making them great for hanging pots. Multiflora petunias have smaller flowers with many open at once. Both have single or double blooms. Milliflora is miniature but have large amounts of small flowers. Groundcover petunias spread and can cover a large area of a garden.
Bugs and Petunias
Despite their popularity and beauty, petunias are susceptible to insect problems. There are a number of worms, beetles, slugs, and earwigs that can attack a petunia.
This insect commonly attack petunias as well as geraniums and nicotiana. If the plants become greatly infested, it is best to just throw them away (not compost). It is possible to handpick the caterpillars off at dusk when they are more active. They lay eggs in the soil, so using fresh soil can help eliminate them too.
There are many species of flea beetles. They can feed on petunia foliage and eat little round holes from the underside while leaving the top layer. Eventually that tissue turns yellow, then brown and dies. The beetle can live through the winter and can be the first insect spotted in spring. Their larvae turn to beetles in July. As soon as beetles detect petunias, their preferred food, they gather quickly upon them. An abnormal growth of the plant can take place. A natural method of control involves covering young plants with mesh until they are more established. Chemicals methods are available at local nurseries.
According to Colorado State University Extension, slugs are one of the most damaging and complicated pests to manage. Slugs can eat entire small leaves or the edges of bigger ones. Slugs hide during the day and are hard to find. The existence of slime trails often is the best sign. Slugs can be controlled in many ways. Eliminate their shelters by removing garden waste and mulches. Increase air movement around plants and reduce high moisture. Use attractants and trap and bait the slug onto the trap. Repellents and barriers work as well. Slugs avoid traveling over coarse materials, so placing them around the plant can give some protection. Finally, molluscicides are pesticides that are effective against slugs. Metaldehyde is the best choice; slugs are not subject to poisoning by most pesticides. Carefully read the directions on the package before applying.
The earwig is a dark, reddish brown bug which is easily recognized by its pincer-like legs on the tip of the stomach called forceps. They don't normally bother humans but eat young plants and damage them. If found indoors, remove them by vacuuming. Destroy their habitat: leaf litter, stones and mulch. Keep them out of buildings by caulking and repairing windows and doors. Chemicals can be used, but consult a local nursery and follow directions carefully.