Q. I’ve been growing gladiolus corms in my flower border for several years. They have always done well in the past but this year the flowers had white and brown blotches on the petals. Do they have a disease, and if so, can we cure it, or should I dig up the corms and throw them away?
A. I suspect that your gladiolus blossoms were not disfigured by a disease but by insects called thrips. Thrips are extremely tiny insects that rasp tender plant tissues and feed on the plant’s juices. They are very hard to see and are easily missed when you are looking at your plants.
Usually you first discover your plants are infested by them when you see the damage they cause. This damage may be disfigured flowers, leaves, or even fruit, depending upon the plant attacked. With gladiolus, the blossoms usually have white or tan blotches where the thrips attacked, exactly what you described.
Although there are pesticides that you could use, the easiest and safest way to control thrips on the corms you have is to dig them up as the tops die back for the winter. Dispose of all the old foliage and other debris to eliminate any thrips it may harbor. Wash the soil from the corms and soak them in 110 degree water for 30 minutes. Allow the corms to dry and store them in a cool dry place until planting time in the spring.
Another effective treatment is to soak the corms for three hours in a solution of 1 ½ teaspoons of Lysol to one gallon of water before replanting in the spring. There are a number of natural insects that will help in the battle against thrips, including ladybugs and lacewings, so using pesticides should be avoided whenever possible. Finally, if it fits with you garden plan, you may want to consider planting the gladiolus corms in a new location in the spring.
Q. Some of the cloves of garlic in my kitchen have begun to sprout. Can I plant them in my garden?
A. Garlic is a relative of onions and shallots and can be grown quite easily in the garden. Although I have planted supermarket garlic with good results when I couldn’t find them at a nursery, your chances of success are greatest with bulbs produced for garden use. In Southern California, fall is the best time to plant garlic.
Plant the individual bulbs in a light, fertile soil with their tips barely covered. Within a few weeks, slender green leaves will appear. The bulbs will grow steadily during the winter and reach maturity by early summer, and the tops will begin to yellow and die. Harvest the bulbs and allow the outer skin to dry in a cool shady area. Rub off the soiled outer skins and remove the dried tops before storing.
If you plant a lot of garlic cloves, you may want to try your hand at constructing garlic braids. You will have to braid the tops while they are still flexible. For braids, harvest the garlic as soon as the tops begin to turn yellow. Wash the soil from the bulbs as thoroughly as possible. Let the garlic rest in a shady area for a day or so until the tops become limp but not dry. Braid them as soon as they become limp, and then allow your braids to complete the drying process.
Ottillia “Toots” Bier has been a UC Cooperative Extension master gardener since 1980. Send comments and questions to firstname.lastname@example.org.
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