Zinnia

Year-round

Zinnia elegans is a fast, heat loving annual that does well in Dallas gardens with full sun, good airflow, and regular water, and it is not toxic to dogs, cats, or horses.

• Give zinnias full sun, at least six hours of direct light a day, in well drained soil with some organic matter. Zinnia elegans is not picky about soil pH.
• Space plants so air can move between them and water at the soil line rather than overhead. Wet foliage is the main way powdery mildew and leaf spot get started on zinnias.
• Established zinnias handle short dry spells, but during hot stretches water deeply and less often rather than a light daily sprinkle.
• Reblooming types like the Profusion and Zahara series do not need deadheading because new flowers grow above the old ones. Older large flowered types will produce more blooms if you cut spent flowers regularly.
• Zinnia elegans originated in Mexico and is a widely grown garden annual across the southern United States. It is not a plant native to North Texas.

Zinnias read as a tidy, colorful bedding and border annual that fits HOA-friendly foundation beds, especially the shorter Profusion and Zahara types kept under about two feet.

Summer

Zinnias handle a Dallas summer well, but watering technique and routine deadheading matter more than usual once the heat sets in.

• Zinnias are one of the more heat tolerant annuals for a North Texas summer, but during the hottest stretches water deeply at the soil line instead of a light daily sprinkle.
• Water in the morning so any wet foliage dries out quickly during the day. Keeping leaves dry overnight is the main way to hold off powdery mildew and leaf spot in summer humidity.
• Deadhead older, large flowered zinnia types regularly to keep them blooming through the heat. Profusion and Zahara type zinnias rebloom on their own and do not need deadheading.
• Watch for Japanese beetles, aphids, and spider mites, which extension sources list among the more common zinnia pests in Texas summers.
• A midsummer feeding with a balanced fertilizer helps zinnias keep pushing new flowers once the first big flush slows down in peak heat.

Fall

Fall planted zinnias, especially the marylandica types, can keep a North Texas bed in bloom right up until the first freeze with routine water and feeding.

• The DFW area's average first fall freeze falls in late November, per the National Weather Service, so a well tended fall zinnia bed can be expected to keep blooming for weeks before that.
• Texas A&M AgriLife has highlighted Zinnia marylandica types, sold as the Profusion and Zahara series, as strong fall performers because they resist powdery mildew far better than standard Zinnia elegans.
• If you already have standard Zinnia elegans in the ground, thin crowded plants and keep watering at the soil line as fall humidity rises, since that is when mildew pressure tends to be highest.
• For standard, non reblooming zinnia types, keep cutting spent blooms through fall to stretch the display as long as possible.
• Do not try to protect zinnias from the season's first light cool nights. They are true annuals that will decline once a hard freeze arrives, so treat this stretch as their last full bloom cycle rather than one to nurse through winter.

A well maintained fall zinnia bed, deadheaded and thinned, keeps curb appeal up right until frost, which is a low effort way to keep an HOA-conscious front bed looking cared for into late fall.

Winter

Zinnia elegans is a true annual and will not make it through a North Texas winter, so this season is about cleanup, seed saving, and getting the bed ready for spring rather than keeping the plant alive.

• Zinnia elegans will not survive a North Texas winter. Once a freeze blackens the foliage, usually around the DFW area's average late November first freeze, pull the spent plants rather than leaving them standing in the bed.
• Clear old zinnia foliage and any powdery mildew affected leaves out of the bed instead of leaving them in place, since the fungus can overwinter in plant debris.
• If you want the same zinnias again next year, collect seed from fully dried flower heads before pulling the plants. Store it in a cool, dry envelope through winter.
• Winter is a good window to work compost into the bed and rework the soil for next year's planting, since the area's average last freeze does not arrive until late winter to early March.
• Zinnias are not native to Texas and do not reliably reseed themselves into a wild stand here, so do not count on volunteers filling the bed. Plan on starting fresh from seed or transplants once frost risk passes.

Spring

Wait until the North Texas frost risk has passed before planting zinnias, then keep young plants evenly watered and well spaced while they establish.

• The DFW area's average last spring freeze falls in late winter to early March, per the National Weather Service's Fort Worth office, so hold off on planting or transplanting zinnia seedlings outdoors until that risk has passed.
• Direct sow seed about a quarter inch deep once nights are reliably staying above 50 degrees Fahrenheit, or set out nursery transplants after the last freeze date for your part of the metro.
• Keep new seedlings evenly moist while roots establish, then ease into deeper, less frequent watering once plants are growing well.
• Give spring plantings full sun and proper spacing from the start. Crowded spring beds are the ones most likely to develop powdery mildew once humidity rises later in the season.
• A balanced starter fertilizer worked into the bed at planting is enough. Skip a heavy nitrogen feed, which pushes leafy growth over blooms.