What is geranium root rot and what can you do to prevent it? And most of all, once you recognize the signs of root rot, is there anything you can do or are your destined to helplessly witness the death of your beloved geranium plant? While geraniums are pretty hardy plants, as other plants they can be susceptible to several diseases and parasites. Root rot is a serious disease that can easily cause the loss of new cuttings or established plants that you have have so much cared about. As with almost every malady in life, an ounce of prevention is worth a pound of cue.
What is Stem and Root Rot?
Geraniums aren’t crazy for water and many geranium fanciers like to say that “geraniums don’t like wet feet.” Root rot, also known as “blackleg,” when the lower part of the plant darkens, is a disease of geraniums that may arise as the result of over watering.
When the water stagnates by the root area, the plant is prevented from getting air to the root and is therefore prevented from absorbing the soil’s nutrients.
This results in cuttings that develop brown/black lesions at the base of the plant, basically the area that is in contact with the soil. Soon, the top parts of the plant and leaves of the affected plants will wilt and die.
It is not unusual to see fungus gnat around diseased plants attracted by the moisture and rotting. The root rot disease is caused by Pythium spp. a type of fungi
What Can be Done?
If the root rot is advanced there is nothing really that can be done, but if caught early, there are a few things that can be done such as removing the plant from the pot and brushing away as much soil as possible from the root ball. After ward, replacing the soil of the pot with a drier type is helpful and so is reducing the rate of watering.
If you tend to put gravel or rocks at the bottom of the pot in hopes of increasing drainage, stop this practice. The University of Illinois found that rocks at the bottom of vases make it harder for water to drain through the soil.
For advanced cases, you can try to apply a fungicidal powder to the roots coating them well and then placing the plant in a new pot with drainage holes and filled with well-draining soil that doesn’t hold water for too long.
However, the University of Illinois extension warns that fungicide products “cannot magically revive a dead plant.” Some websites suggests watering with diluted hydrogen peroxide for root rot. This may be worth a try if there’s nothing to lose.
“It is a myth that a layer of gravel (inside the bottom of an individual pot) beneath the soil improves container drainage. Instead of extra water draining immediately into the gravel, the water “perches” or gathers in the soil just above the gravel. The water gathers until no air space is left. Once all the available soil air space fills up, then excess water drains into the gravel below. So gravel in the bottom does little to keep soil above it from being saturated by overwatering.”~University of Ilinois
Preventing Root Rot
When taking cuttings, choose disease-free specimens. It’s a good idea to dust their base with a combo of rooting hormone and fungicide, with a ratio of about 90 percent hormone and 10 percent fungicide.
Use a sterile, well-draining media that won’t retain excessive moisture. Avoid garden soil which often contains fungal spores.
Choose pots with good drainage holes and prevent using gravel or rocks at the bottom of the pot. Use new pots or if you must use an older one, make sure to clean it with a 10 percent bleach solution.
Establish good insect control against moisture loving bugs such as fungus gnats and shore flies. Avoid over-fertilization. And of course, over watering should be avoided at all costs. Learn here how often you should water your geraniums.
- University of Minnesota, Black Root Rot in Flowering Annuals.
- University of Illinois, Pythium Root and Stem Rot of Bedding Plants