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Pansies can be considered as annuals, perennials or biennials, depending on the variety. They should last at least one season. When they start collapsing soon into spring or early summer, it raises the question of why are my pansies dying?
There are several causes. The most common is watering issues. Too much moisture drowns the roots, and not enough will starve the plant.
Other causes include excessive heat, low soil pH, over fertilizing, nutrient deficiencies, or fungal and soil-borne diseases.
Explore the Causes of Premature Dying Pansies
1 – Excessive Temperatures
Pansies are cool-weather garden plants, although they can be grown indoors using a window box depending on the sunlight conditions.
The stronger the sunlight, the more heat stress can affect these plants. Although tolerant to full sun, the intensity of direct sunlight around midday can be too stressful. Ideally, they should be planted in a location that gets full sun in the morning then shade later in the day.
For pansies grown in window boxes, east facing windows have optimal light conditions because the sun rises in the east then sets in the west. North facing windows never get full sun so photosynthesis will be slower, making it difficult to get pansies to bloom, or grow by much.
South facing windows get the most intense heat, so in the summer months, the heat from south facing windows will be far too intense for pansies.
2 – Soil Acidity
The soil pH can be too low putting pansies at risk of thielaviopsis, more often referred to as black root rot, as that is the symptom the disease causes.
This is a disease that kills pansies. A contributor to its development is the soil pH being below 5.8.
Pansies need to have acidic soil for all the nutrients to be usable by the plant. Alkaline soils have much less available nutrients. Early symptoms of nutrient deficiency from a soil pH imbalance are pale foliage, poor blooming, and yellowing leaves near the base of the plant.
For best results, aim to maintain the soil pH between 5.4 and 5.8, but no higher than 5.8 as that is when black root rot can take hold.
3 – Towing the Line with Watering
Pansies do not need a lot of water, but they do need to be watered regularly. How often depends on the soil type.
While they do thrive in almost any acidic soil type, the faster it drains, the better. Clay soil is slow to drain and (more often than not), alkaline. Sandy soils are faster draining and tend to be more acidic.
Chances are, if you have slow draining soil, you will have two problems. Near constantly moist or damp soil with an unsuitable pH level. The first soggy soil issue will lead to root rot and the pH imbalance will reduce nutrient uptake.
Even with ideal soil, pansies need to be watered daily, preferably in the morning to allow the rest of the day to dry out. When the soil becomes waterlogged, root rot can take hold because oxygenation is reduced in compacted soil.
As a guideline, aim for 1-inch of water per week, remembering to factor for rainfall in garden beds. Container grown pansies should be watered at the soil level to maintain slightly moist soil. Never drench the soil or let it stay damp or soggy for too long.
It’s also important to keep water off of the leaves. Pansies are susceptible to a number of fungal diseases such as powdery mildew, and rust disease. Both of these can be guarded against by watering the soil in the early morning to give them time to dry out through the day.
4 – Nutrient Problems
Fertilizers are good for pansies, but only in moderation. A balanced fertilizer, i.e., a 10-10-10 or 20-20-20 all-round fertilizer is ideal. Granular is preferable as opposed to liquid because the fertilizer needs to be in the soil, not on the leaves.
Foliar fertilizer sprays can cause leaf burn. Granular fertilizers are easy to sprinkle onto the soil then water it in well. Another benefit to granular fertilizer is that they release nutrients slower. Liquid fertilizer is released more quickly.
How much needs to be applied depends on the size of the garden bed or the pot the plant is in. As a guideline, only a teaspoon of fertilizer is needed per square foot in a garden bed.
In containers, or window boxes, even less fertilizer is recommended – just half a teaspoon per 10-inch pot.
Adding any more is likely to lead to pansies becoming leggy. Leggy pansies can be a sign that they have too much fertilizer in the soil. When this is the case, the soil should be flushed to prevent excess salt accumulation.
The long-term implications of overdoing it with fertilizer is that plants grows faster than the roots can develop. Without the foundational support of a healthy root system, the pansies will be doomed from an early age.
Another thing to consider is the spacing of your plants. In garden beds, they ought to be planted with 6-inch spacing minimal. For trailing varieties of pansies in hanging baskets, spacing should be between 6-inches and 10-inches.
The more space there is available, the less each plant will have to compete for nutrients in the soil.
6 – Stress
As with most plants, stress is a common culprit for their early demise. Especially for baby plants that are too weak to cope with huge environment changes like moving from a plant nursery to your garden. The light, temperature, soil, and humidity all change in too short of a space of time.
The more you can match the growing conditions, the better. Guides about planting and caring for pansies are a good start. You can learn about the soil temperatures that need to be maintained at 45oF to 65oF, humidity levels being 40% to 50%, light being bright in the morning, shaded in the afternoons, etc.
These are all things that will happen in nurseries. Less so in chain stores that do not take as much care with plants.
7 – Thielaviopsis – Black Root Rot
Thielaviopsis basicola is a soil-borne fungus that attacks plant roots. Symptoms of this is the blackening of the plant roots and stems.
It starts below ground, stunts growth, causes wilting, but by the time stems blacken above ground, the underground decay is too far gone to be treatable.
The fungus attacks primary and secondary roots causing the entire plant to decay, usually rapidly.
When black root rot takes hold, next season’s plants should be placed in new soil in a different location as the fungus can remain dormant in soil for years.
8 – Phytophthora Crown Rot
Phytophthora is a water mold that attacks the plant just above the soil line. This is mostly problematic for pansies in warm and wet weather. Mostly because the spores spread by water droplets.
Part of the problem is that pansies are cool weather plants. As this is a water mold, it is only a problem in wet weather, or if you happen to overwater the soil – and keep on adding more water.
Always remember never to drench the soil as that is when any fungus can germinate and spread fast.
9 – Fungal Diseases
Pansies are susceptible to numerous fungal diseases, some of which include powdery mildew, cercosspora leaf spot, anthracnose, and bortrytis blight. Fungal diseases are only fatal to pansies when left untreated.
Each of these show symptoms on the foliage such as dark spots, blotching, lesions, or in the case of blight and powdery mildew, a gray fuzzy mold coating the leaves. These can be effectively treated using fungicides, all of which have directions on the label.
Diseased roots are rarely treatable, which is why soil care is prudent to the survival of pansies. Care for the soil to protect the roots as that is what will keep the rest of the plant thriving.