Petunias are wonderful flowering summer annuals that come in so many different colors and color combinations that they will brighten up any garden or patio with their colorful blooms. They are also useful for their different growth habits.
Some are trailing and like ground covers, perfect for trailing in hanging baskets, while others are more upright-growing and perfect for containers. Some have large blooms, and others are a little smaller.
Generally, they are easy to grow with the right conditions and very rewarding, with many flowers all summer. Wilting, however, is a sign of stress. Here are the ways to save your petunias from wilting or saving them after they have wilted.
Lack of Water
The most common cause of wilting is obviously the lack of water. Several factors dictate the amount of water they need. First, it will be the type of petunia—for example, spreading ground cover varieties require more water in general.
Second, it is the amount of summer rainfall in the area. Then, there are factors like cold and heat in the climate, and bouts of either, like a heat wave, will have an effect.
These flowering plants prefer the soil to be constantly moist but not waterlogged, with a small amount of time between irrigation sessions so they can dry out.
The rules are different for containers. Because the volume of soil in a hanging basket or pot is much smaller than in the garden, it tends to dry out quickly. Some containers may need watering daily.
When a petunia wilts, first check the soil. If it’s dry, add water, but if it’s still moist, there may be another issue.
Too Much Water
Like too little water, too much moisture could also cause wilting petunias. If the roots are effectively drowning, this will stop the plant from taking up water and essential nutrients through its capillary system to reach the leaves and flowers at the end of the stems, causing it to wilt.
Avoid supplementary irrigation for a while to remedy overwatering, but check every day to see if the soil has dried out. Constant rainfall is no help, and if the plants are in containers, move them to an area where no water can reach them.
If the soil has enough drainage, garden petunias should recover quite well once the rain has stopped. If the problem persists, container plants may need to be repotted. Once the plant has been removed from the pot, cut away any damaged roots before repotting them into fresh soil. Add extra drainage materials like perlite or vermiculite to the potting soil before repotting.
Not Enough Drainage
The amount of moisture petunia needs depends on the soil’s water-holding capacity and drainage. Well-draining soils are essential so that the roots are not waterlogged.
However, the balance is between ensuring water drains well and maintaining moisture, especially in containers. A lack of drainage will send the plant directly into the ‘Too Much Water’ category. Ideally, a potting mix blend contains ingredients like compost, perlite, vermiculite, and peat moss to properly balance moisture retention. Don’t be afraid to re-pot, if necessary.
Not Enough Sun
These flowers are well known for liking plenty of sunshine and may not bloom without it. They need at least six hours of sunlight a day to flower well. They will cope with a bit of shade but need that daily burst to perform at their best. If they are not getting the six hours, they may tell you by wilting.
To fix the problem, they will need to be moved to a sunnier position after you have checked that it’s not any of the other more common problems that can cause them to wilt. Containers may need to be relocated into the sun, but check the irrigation schedule, as the hotter they are, the more moisture they will need.
High Humidity
Petunias do not like fluctuating humidity, and growing in areas with it may be an issue. They prefer to be within the range of 40-60% humidity. High humidity can cause the leaves to suffer from too much moisture on their surface and may increase the chance of fungal diseases.
Too Much Heat
Some petunias wilt in high heat, but these days, some varieties, like the Supertunias, can withstand high heat conditions. If your temperature is outside the range of 70-80°F (21-27°C), choose the more heat-tolerant cultivars.
Pests
Plants are very clever and will often wilt if they suffer from a pest invasion. Petunias, especially, are magnets for sucking insects like aphids and chewing insects like budworms and slugs.
When they get chewed, or the sap is being sucked out of their leaves and stems, they will lose their vigor and start to wilt. By controlling the pests, you can control the wilting problem. Neem oil will go a long way to remedying the situation.
One of the better ways to control pests is to prevent them from attacking your petunias in the first place. This prevention method is simple: prevent petunias from wilting by providing them with the correct amount of moisture, nutrients, and sunlight. Plants that are stressed will soon have pest problems.
Diseases
The leaves are susceptible to some fungal diseases. Diseases like white mold, verticillium wilt, gray mold, and root rot can all lead to petunia leaves and stems wilting. Once again, prevention is the key.
Any supplemental irrigation should be done at ground level, which prevents the water from sitting on leaves and increases the favorable conditions for fungal diseases to grow. Drip irrigation or soaker hoses are ideal for watering at ground level, and there will be no splashing onto leaves.
Water in the mornings so that the day’s heat evaporates any potential water on the leaves. Ensure petunias are spaced correctly in the garden, with plenty of space between them for good air circulation.
Remove and destroy any diseased parts of the annuals immediately. Never add infected leaves and stems to compost. A fungicide may be necessary.
Ethylene in the Air
An interesting fact about petunias is that they are highly sensitive to ethylene in the air, which can cause wilting. This gas is released from decaying flowers, fruits, and vegetables, including their own flowers.
There is also ethylene in exhaust fumes, which means that petunias transported long distances often have an issue of wilting and dying flowers and leaves when they get to their destination.
Ethylene is produced in transport when temperatures are high, the air is dry, and even due to the vehicle’s vibrations. The vibration causes the flowers to self-pollinate; as a rule, the flowers will generally die within 24-36 hours. This unnatural cycle causes the flowers to wilt quickly and die within twelve hours after the release of ethylene.
The wilting of the flowers will spread to all the flowers, and the stressed annuals will become very susceptible to diseases like botrytis.
The fix is to avoid transporting these flowers long distances. You will notice the effects in some nurseries; avoid purchasing those varieties.
