Have your colorful and happy zinnias begun to droop and wilt? There is always a reason behind sad-looking zinnias, and a little investigation will reveal what’s wrong with your plants.
Zinnias are annuals that develop long, strong stems with one large, multi-petaled bloom at the top. When they are healthy and happy, the plant stems are straight and can reach up to 4-feet tall when mature.
If the stems begin to wilt and the flower heads are drooping, there’s something wrong with your zinnia. Fortunately, you can do a few easy things to bring your zinnia back to life.
Zinnias may wilt or droop after being transplanted because they are suffering from transplant shock and need to put their energy into adjusting to their new environment.
Wilting may occur on a newly transplanted zinnia because it’s thirsty. Some of the delicate, hair-like roots of the plant were almost certainly damaged during the transplanting process.
Until the plant recovers from transplant shock and can re-grow more of these roots, it can be hard for them to absorb enough water as usual.
To stack the odds against wilting, give the transplant more water. Thoroughly water the soil at the base of the plant and keep the soil consistently moist until the plant stands upright again.
To help prevent transplant shock and wilting, water your zinnias thoroughly before transplanting and immediately afterward. Also, transplant them in the late evening so they will have a little time to recover during the cool of the night.
Starting off your flowers in healthy soil will help them hit the ground running. Check out a few of my favorite supplies for all my flowers:
My favorite garden soil supplies
When you know what condition your soil is in, it’s much easier to add anything that’s missing before your plants start to suffer. Find out your soil’s pH and macronutrient levels with an easy Soil Test Kit. Even without a soil test, worm castings are a safe bet to add to any garden, and your plants will love them. Wiggle Worm Soil Builder is a high-quality amendment that I add to all my garden beds that need a boost. Finally, learn why I don’t till my garden anymore with the “godfather” of no-till, Charles Dowding’s No Dig Gardening.
Zinnias need plenty of water to grow their best, so drooping and wilting leaves are one of the first signs that they are suffering from drought stress.
Zinnias need at least one inch of water per week, sometimes more if the weather is hot and dry. Keep the soil moist down to 6-inches deep. The plant roots grow deep to keep the tall plant anchored securely in the soil.
If you grow zinnias in a container, the container should be 10-12 inches deep. The generous depth will allow the water-absorbing roots plenty of space to grow downward since the container will restrict their lateral growth.
Also, avoid using black liner pots. Black absorbs heat and makes the soil hot, and moisture will evaporate more quickly, making your zinnias more likely to wilt on a hot day.
Instead, use a light-colored container or place the black liner pot inside of a decorative pot that is light-colored so it will reflect the sun instead of absorbing heat. A wooden planter will insulate the liner pot and keep the soil temperature lower on a hot day.
During the summer heat, zinnias will need to be watered several times a week to prevent them from wilting. Be careful not to overwater the plants and make the soil soggy as this will make the plant prone to develop diseases.
The heat of the day
Many flower varieties wilt during the day’s heat, especially those planted in a full sun location. Zinnias wilt in the heat of the day because the plants release moisture through transpiration.
Transpiration in plants is equivalent to sweating in humans: it’s how plants regulate their temperature.
Transpiration occurs at a higher rate during the heat of the day and faster than zinnias (among many other types of flowers) can take water up in their roots and distribute it to the leaves.
The result is drooping zinnias. The good news is that the plants will perk up as soon as the air temperature lowers in the evening.
Zinnias grow best in a full sun location but planting them in an area that will receive a little shade in the afternoon will prevent them from wilting on hot days. This is especially needful if you live in areas that have hot, dry conditions throughout the summer.
Plant zinnias in a location that will receive the full sun from the early morning until mid-afternoon. This will provide them with 7-8 hours of direct sun and shade them in the hot afternoons.
Disease or pests
Zinnias are hardy plants. That’s one of the many reasons they have been a popular flower in the home garden for centuries.
They even provide benefits to other plants through their hardiness and deer resistance. Deer do not like the taste of zinnias and rarely ever bother them. If you plant zinnias near other flowers and vegetable plants, the deer will usually leave them alone as well.
For all their hardiness, beauty, and benefits, zinnias still have a couple of weaknesses that can make them wilt and droop.
Zinnias need plenty of airflow between and around the plants. If they are planted too close together, often have wet foliage, or the soil remains overly wet, they can develop powdery mildew or bacterial wilt.
Powdery mildew looks like white talcum powder on the plant leaves. It sometimes spreads to the stems and flowers.
It may not cause any issues for the zinnia, aside from making it look bad. If the powdery mildew is severe, the leaves may wilt, become distorted and discolored, and fall off the plant.
Bacterial wilt starts as a dull, gray, watery spot on a leaf. As the disease progresses, the leaf will develop yellow spots and wilt. Sometimes the bacterial wilt manifests on the leaves as small, reddish-brown spots with grayish centers.
Bacterial wilt is fast-spreading and highly contagious between the plants. If your zinnias are wilting, inspect the leaves for any discolorations. If bacterial wilt is suspected, remove the entire infected plant and discard it away from all other plants.
Wash your hands before touching other plants to prevent spreading any disease spores.
To help prevent powdery mildew and bacterial wilt, space zinnias 9-12 inches apart so air can flow freely between the plants and avoid getting the foliage wet by watering at soil level with a watering wand or drip irrigation.
The only pests that bother zinnias are caterpillars, mealybugs, and spider mites. They typically don’t cause the plants much of a problem, but if you notice the leaves wilting or drooping, it could be one of these pests.
Inspect the plant for pests, and be sure to look on the underside of the leaves. The caterpillars can be hand-picked off the plant, and you can kill mealybugs and spider mites with DIY insecticide or other organic pest control products.
Not enough sunlight
If zinnias are not getting enough sunlight, they will become “leggy” and look less filled out than those grown in full sun. Legginess is most common with seedlings, but mature plants can also experience sparse growth due to insufficient sun exposure.
Zinnias need 7-8 hours of direct sunlight a day. The plants can thrive in 6-hours of direct sunlight, but less than 6-hours of sunlight a day will cause them to be leggy and have wilted leaves.
If your zinnia is wilted and in a shady location, move it to a sunnier spot. The plant will perk up and develop new growth and fresh blooms in a few weeks.
For more on growing zinnias in shady gardens, check out this article: Can Zinnias Grow In Partial Shade? (Yes, But Not Optimally).
More resources for robust zinnias
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