Petunia seedlings turn yellow: what to do


Petunia is an amazing flower designed to decorate garden flower beds and balconies. The South American plant has perfectly “taken root” in Russia and has been popular with beginner and experienced flower growers for many years now. Petunia is grown mainly by seedlings, in order to speed up the flowering process. However, unfortunately, sometimes in the cultivation of seedlings of petunias, problems may arise. The most common nuisance is yellowing of the leaves. But why does the seedling of petunia turn yellow, what could be the reasons and how to rectify the situation? The answer to these and some other questions can be found in the article below.

The reasons why petunia seedlings turn yellow

Excess moisture

With the appearance of yellow, fragile leaves in seedlings of petunias, you should think about whether the roots of plants suffer from excessive moisture. So, the most common cause of yellowness is root rot. The roots of petunia, being constantly in an environment with high humidity, are experiencing oxygen starvation, stop developing and absorb nutrients from the soil. As a result of this anomaly, the leaves of petunias turn yellow and eventually fall off.

The root cause of excessive moisture accumulation can be the lack of drainage or frequent watering of plants. Correct the situation and save the petunias in this case is possible. To do this, in the bottom of the container with the seedlings should be done drainage holes and remove the yellow leaves from the plants. With a strong decay of the petunia should be transplanted into a fresh, well-drained soil, before treating the roots with an antifungal drug.

Important! When sowing petunia seeds on the seedlings should be filled with clay or small pieces of red brick on the bottom of the tank.

Lack of nutrients

For growing seedlings of petunias, it is necessary to use a soil saturated with nutrients. You can buy it or cook it yourself by mixing garden soil with peat and sand. Also in the process of growing seedlings, petunias need to be fed. Otherwise, as the seedlings grow, there may be a lack of beneficial trace elements. Especially for petunia are important substances such as iron, sulfur, zinc and magnesium:

  • With a lack of iron, petunia leaves turn yellow, but the green color of the veins on the leaves remains. Such symptoms suggest the development of chlorosis. It is possible to replenish the amount of iron in the soil by using the preparations Cytitis, Ferrovit.
  • The yellow leaf plate of petunia, with twisted dry edges, indicates a lack of magnesium. This trace element can be replenished by the use of magnesium sulfate.
  • The lack of zinc is manifested in the form of small yellow blotches on a leaflet. Over time, yellowing covers the entire leaf plate, which leads to its death. For the treatment of seedlings in this case, it is recommended to use zinc sulfate.
  • In the case when the yellow leaves of the seedlings of petunia eventually acquire a red hue, it is worth talking about the insufficient amount of sulfur in the soil. You can add the missing microelement by sprinkling the soil with grated sulfur.

If there are signs of lack of a trace element, you can also use complex fertilizers. They contain all the necessary minerals and become a source of healthy nutrition and enhanced growth of seedlings. For fertilizing plants, it is recommended to alternate the root and leaf feeding.

Important! Nutrient deficiencies are more likely to be experienced by adult petunias growing in pots.


Insects can be another reason for the appearance of yellow leaves of petunia. Despite the fact that the seedlings are in the room, they can parasitize on it:

  1. Spider mite This small insect has a red color and “prefers” to life conditions with high soil moisture and low air humidity, which is quite typical for seedlings of petunias. Spider mite is adapted to domestic conditions and open ground. The presence of this pest is indicated by the entangling cobweb on the leaves, their yellow color and slow growth of the seedlings. You can defeat a tick by treating the leaves with soapy water. Also in the fight against the pest use powdered sulfur dressing and special chemicals that can be used safely in the home.
  2. Aphid is another pest that is well known to all gardeners and flower growers. These small insects settle on the underside of the leaf and are often invisible to the eye, until serious problems with the plant appear. Aphids feed on the leaf sap, causing them to turn yellow and curl, then dry out. It is rather difficult to fight with aphids on seedlings and, probably, for large areas of infestation, it is easier to destroy plants than to process them. However, especially painstaking flower growers suggest using a solution prepared from soapy water and nicotine sulfate (1 g of a substance for 1 liter of soap solution). The resulting tool should be sprayed seedlings and wrap it in a plastic bag for a day. After a set processing time, the seedlings are washed with clean water.
  3. The whitefly is a frequent guest of glazed balconies, loggias and greenhouses. This insect has the appearance of a small, light butterfly. As a rule, her fluttering over petunia ends with the appearance of white pigment spots, and then yellowness on the leaves. Soon such leaves curl and fall, the plant dies. In addition to direct harm to plants, the whitefly can be a source of fungal diseases, which disputes. In the fight against pest use only special drugs.

When growing up seedlings of petunias, it is worth remembering that it is much easier to deal with a pest in the initial stages of a lesion. Late detection or absence of measures to prevent the harmful effects of pests on seedlings leads to the imminent death of petunias. You can learn more about home pest control methods at home: their videos:


The reason that the foliage of petunias has turned yellow may be a fungal disease - powdery mildew. This disease rarely affects plants growing in protected conditions, however, its source may be unprocessed soil, the contents of the spores of this fungal disease. Often, spores are in sleep mode and are activated with sudden changes in temperature and humidity. Excessive introduction of nitrogen-containing bait can also trigger the development of this disease.

Powdery mildew manifests itself in the form of a dense white deposit that covers the leaves of petunias. As a result of such exposure, seedlings lose their elasticity, become lethargic. The leaves under the veil of bloom become yellow and then brown in color.

You can relieve seedlings from the disease by treatment with "Fitosporin", "Topaz". Before processing these substances, the damaged parts of the seedlings should be removed and, if possible, burned. Adult petunias infected with powdery mildew are transplanted into a new soil and a decontaminated pot.

Important! Fungal disease can be prevented even before sowing seeds of petunia for seedlings, by disinfecting the container and soil intended for cultivation.


In order to avoid all the above troubles, you should closely monitor the seedlings of petunias. For watering plants it is better to use soft, settled water. It can also be softened by adding a small amount of lemon juice. Regularly (1 time in 2 weeks) young petunias should be fed with complex fertilizers that will allow the seedlings to develop harmoniously. When pests are detected, measures should be taken as soon as possible for their destruction, otherwise the seedlings will become a source of food and prosperity for them. So, only an attentive, caring owner will receive a reward for his work healthy, strong seedlings of petunias, which will decorate the flower beds and pots with bright, beautiful flowers.