A: Zinnias can be prone to several bugs as well as the most common problem — powdery mildew, which is a disease that turns the leaves whitish, then brown. Leafhoppers are another zinnia-attacking bug that make spots on the leaves but also spread a disease that can kill the plants.

How to Care for Zinnias

1. Maintain moderate soil moisture and fertilize lightly to maximize growth and blooms.
2. After zinnias flower, cut off the old flowers (a process called “deadheading”) to encourage more flowers to form.
3. Zinnias are annuals and will die with the first hard frost of fall.

One of the most common diseases that can cause the leaves of your zinnia to turn brown is Alternaria leaf spot. Holes will appear and the leaves will begin to fall off. If you do not treat this problem quickly, the foliage will wilt, and it will turn completely dry and brittle.

Only two diseases are commonly troublesome on zinnias (Zinnia elegans), powdery mildew and Alternaria blight. Alternaria blight is the most common and conspicuous. Spotting of the foliage caused by the fungus, Alternaria zinniae, is the most conspicuous symptom of zinnia blight.

Just as too much or not enough light can cause yellowing seedling plants, too much or too little water or fertilizer could also be the problem. Overwatering, however, is a very common cause of sickly plants. Let the soil begin to dry a bit between waterings.

Wilting because of hot and dry conditions occurs because plants are releasing moisture through transpiration faster than they can take water up in their roots and distribute it to the leaves. Wilting also serves to protect the plant’s leaves from the sun.

Zinnias are heavy feeders, so plan to fertilize them regularly and often, as this will encourage lush, colorful blooming. Use a balanced 10-10-10 or 6-6-6 fertilizer, applying about one pound per 100 square feet for a first spring planting application.

Once they are 3 to 4 inches high, water them deeply a couple of times a week, depending on weather. Zinnias aren’t drought tolerant, but they like their soil a little on the dry side. The soil should not be continuously wet. * If we experience overcast June weather, cut down on watering.

To do this, insert the stems in boiling water for 20 seconds or hold them over a candle flame. Place the cut zinnias in a container of lukewarm water for several hours or even overnight to promote hydration.

Foliage Curls, Puckers, Turns Yellow Due To Aphids They tend to cluster on tender, new growth on zinnia stems and on the undersides of young leaves. They suck juices from plant cells, causing foliage to curl, pucker and turn yellow. Often the leaves and blossoms become stunted.

Aphids are common insects that damage zinnias when they puncture the leaves and stem to feed on the sap, or juice of the plant, says the University of Illinois Extension. Aphids are usually bright green. Mites are even smaller and look like tiny black dots.

Fungal leaf spot or Bacterial leaf spot diseases are likely to ‘eat’ holes in your Zinnia leaves. Aphids are also common pests of Zinnias that eat the leaves. Caterpillars like Leafrollers, Cabbage looper larvae, Army worms and Cutworms can eat holes in your Zinnia leaves.

Zinnias can withstand moderately dry soil conditions but do better with supplemental watering. In general, zinnias typically need 1 inch of water once every five to seven days. However, check soil…

Zinnias (Zinnia spp.) reseed easily, creating a cut-and-come-again garden each summer. Heirloom varieties, cultivated for more than 50 years, are open pollinated and grow into plants identical to their parents.

Zinnias will need to be watered regularly. Although they come from arid regions and love hot weather, they do need moisture. Plantings should be fertilized at least twice during the growing season. Use a balanced granular or water-soluble fertilizer, for instance, one with 20-20-20 on the label.

Ensure that your zinnias are growing in full sun. In order to get maximum blooms from each plant, they need a minimum of six hours of sun per day. Water the zinnia plant when the top inch of soil begins to dry. Snip off dead and dying flowers and remove them from the planting area.