Does your Sunpatiens look wilted? Does it seem like it’s rotting away? The culprit is a fungal infection due to soggy soil. Learn more about what causes this rot, how to treat it and what can heal your rotting flower.
Plants of the Impatiens family love water but they’re vulnerable to a host of water-related diseases. Hybrids like Sunpatiens ® are bred to resist, but extreme conditions can weaken the plant and trigger disease.
Downy mildew is a fungal disease responsible for killing entire beds of Impatiens recently, and Sunpatiens ® is resistant to the disease. However, other fungus that lead to root rot are still potent. They might threaten the plant’s survival.
Sunpatiens is vulnerable to two fungus: Pythium and Rhizoctonia.
Unfavorable conditions trigger these root rots:
Note: if all seems lost, don’t despair! All you need is a single healthy-looking stem to start a new cutting!
Both root rots, Pythium and Rhizoctonia, result from fungus contamination. The fungus is often already present in soil in a dormant state. When moisture and heat rise, the fungus looks for host plants. Wounds in roots are entry points. From there, it spreads through the plant. Both fungus cause root rot in other plants, such as this diseased vinca.
Black strands appear along stem and leaves. They’re clearly visible when a diseased stem is sliced open: black spots mark contaminated channels from health ones that convey sap and nutrients up and down the stem.
The plant starts rotting from the ground upwards.
The rotting starts at the crown or top of the Sunpatiens plant and then progresses downwards. The name for this is crown rot.
Sunpatiens leaves turn pale green and then yellow, always harboring a lot of moisture. They droop over as the structural integrity of the stem collapses.
Diseased cells accumulate and the plant disintegrates into a slimy mush.
| Pythium | Rhizoctonia | |
|---|---|---|
| Where it starts | At the roots, and climbs | At the crown, and descends |
| What you see | Black strands along stem and leaves; sliced open, black spots mark the blocked channels | Pale green leaves turning yellow, heavy with moisture, drooping as the stem gives way |
| How it ends | Rot works upwards from the ground | The plant collapses into a slimy mush |
| What triggers it | Standing water, heavy clay, poor drainage | Heat and moisture together, plants set too close |
In a nutshell: dry the root ball out, and control watering after that.
In pots, this is extremely rare, but if ever you recognize symptoms described above:
Always use fresh soil mix for potted sunpatiens ®. Disinfect pots and tools with white vinegar beforehand, dry it off before planting.
If the ground is lower than surrounding areas, with heavy soil, your Sunpatiens risk root rot.
Sweep mulch aside and press your finger to the ground: if dusty and dry, start watering again. However, if clumps of dirt stick to your finger, wait for a day or two.
Don’t worry about plants not getting enough water for now: they send roots deeper underground.
Ideally every 2 inches. Excess water seeps underground and air circulation around roots increases. A sturdy pencil can do the trick, but an iron or steel rod with a sharp tip is easier. It’s like aerating a lawn. Prevent spread of fungus by dipping gardening tools in 40+ proof alcohol between jabs.
If you want maximum protection, uproot sick plants entirely to protects nearby ones. Loosen soil up and remove the diseased plant out delicately to pull roots out instead of slicing through with a spade. This avoids open wounds in roots of healthy neighbors.
To be thorough, check with the nursery you purchased the plants from: perhaps other customers have the same problem, meaning the whole batch is infected.
It’s often easy to discern. Having the impression of a drenched, completely waterlogged soil is the start of it. Clay soil can’t drain and tends to retain water, forming a thick paste.
Mulch with wood chips hints to the answer:
In extreme cases, roots appear above soil, weaving in and out of mulch. They’re reaching for air. Such soil types are full of water, and roots need to breathe as much as leaves do.
Fungal infections remain in soil for years. If you’re not able to improve the soil drastically, set up a raised garden bed. Indeed, a raised garden is a great way to reduce risk of root rot for all plants.
Another option is to find other plants that love wet, moist soil.
It is however quite easy to make clay soil lighter and of course remember to spray organic fungicides every fortnight for two months to control contamination.
If you live in a mild climate (no frost or freezing), you can plant Sunpatiens again the following year. But if the weather gets cold spare yourself the effort and either sow green manure which will further enhance the clay soil or go for nice beautiful winter plants.
Read also:
Both look like a wilting plant, and the two call for opposite actions. Watering a plant that
is rotting finishes it off, which is why this is worth settling before anything else.
| Simple thirst | Root or crown rot | |
|---|---|---|
| When it wilts | In the afternoon heat, and it recovers by evening | All day, and it is still limp in the morning |
| The soil | Dry two inches down | Damp, or wet, two inches down |
| The stem at the base | Firm and green | Soft, darkened, sometimes slimy |
| The leaves | Droop evenly, colour unchanged | Pale then yellow, heavy with water |
| What to do | Water thoroughly, then mulch | Stop watering. Lift, cut away the rot, take a cutting from a clean stem |
They are sold under one name but come in three quite different sizes, and a plant crowded into
a pot meant for a smaller series is a plant that will rot. The label at the nursery says which.
| Series | Habit | Size | Best used as | What to know |
|---|---|---|---|---|
| Compact | Mounded and dense | 14 to 24 in (35 to 60 cm) | Pots, window boxes, edging | The one to choose for a container. Needs the most frequent watering of the three |
| Spreading | Low and wide | 24 to 36 in (60 to 90 cm), spreading further than it is tall | Hanging baskets, ground cover | Give it room. Crowded plants hold damp air at the crown, which is how crown rot starts |
| Vigorous | Upright and shrubby | 36 to 48 in (90 to 120 cm) | Large beds, seasonal screening | Deep roots, so it tolerates a missed watering better than the other two |
Whichever it is, spacing matters more than variety. Planting density appears on the list of
conditions that trigger both rots, and it is the one entirely within your control.
