How to Care for Petunias and Fight Tobacco Worms with Chemicals Wasps or Lacewing Larvae
By: R. Renée Bembry
Desert dwellers enjoying mild winter climates can plant petunias in autumn and enjoy colorful petunia flora from springtime all the way to early summer. Growers in other climates should plant petunias after danger of frosts and preferably, when soil is at least sixty degrees. Planting during this time should allow growers in milder climates to enjoy blossomy flora throughout the summer.
Petunia Color Spectrum:
Petunia colors range from pale pinks to deep reds and include purples, yellows, blues, and whites. Some types grow single funnel shaped flowers and other types produce double flowers. Single petunia flowers have open throats and consist of four to six petals. Some double petunias have so many petals they look like carnations. Petunia blooms are fragrant.
How Much Water Petunias Need:
For the most part, caring for petunias means providing them ample water, sufficient sunshine, and plenty of well balanced soil in which to grow. With that said, however, single petaled petunias are capable of withstanding poor soil and alkaline soil when the soil has good drainage.
When caring for petunias gardeners should also provide them plenty of growing space. Set new plants in ground approximately eight inches apart for smaller varieties and as much as eighteen inches apart for larger growing types. Let pot tags dictate the distance for the type of petunia you purchase. Planting petunias in full sun encourages continuous blooming at regular intervals.
Pinching and Fertilizing for Greater Blooms:
Established petunia plants need their gardeners to pinch back half their branches thus allowing the plants to become more expansive.
In addition to pinching established plants for fullness, cut back ragged plants at summer’s end following blooming period. Cutting ragged stems will encourage new growth similar to the pinching strategy. Newer growth should rejuvenate plants.
Proper petunia care also means providing monthly fertilization to obtain the best growth results possible. Select from assortment of fertilizers available at local garden centers.
Growers residing in smoggy environments may have to deal with white petunias and seedlings suffering from spottiness brought on by dirt in the smog. Spottiness usually clears up on its own when skies clear.
Treating Petunia Pests:
Growers might discover tobacco budworms can become problematic for petunias by laying eggs on the plants. When the eggs hatch, Heliothis larvae exit the eggs and eat the petunias. Gardeners experiencing this problem can care for their petunias by treating tobacco budworms with sevin or Diazinon.
Gardeners preferring not to use chemical treatments to get rid of worms on their petunias can use trichogramma wasps to destroy the eggs or release lacewing larvae to eat the moth larvae.
Whether opting to use chemicals or live controls to rid tobacco worms, application timing is crucial when treating petunias. Moths lay most Heliothis eggs in the week following a full moon. The best way to combat the larvae is to treat petunias during the same periods eggs are laid. This means release lacewing larvae or trichogramma wasps the week following each full moon so the live controls can eat or destroy moth eggs before the eggs hatch and destroy the petunias.
Gardeners using chemicals should apply their control once every week. Growers should also be mindful of the fact that chemicals cannot penetrate flower buds and thus cannot destroy worms that manage to crawl inside petunia flower buds. Should growers suspect worms are inside their petunia buds, they should remove and destroy all infested petunia clusters that display substantial damage.
Although petunia thick foliage is a tad sticky, handling the foliage is not at all offensive. Gardeners could opt to wear gloves when caring for their petunias.