Venus fly trap (Dionaea Muscipula), as its name suggests, is a small carnivorous plant.
Featuring hinged leaves lined with teeth around the edges, the plant is known for its unique characteristic of catching and eating small insects.
The plant is native to the subtropical wetlands of North and South Carolina and is the only member of the genus Dionaea, from the Droseraceae or sundew family.
Growing from a bulb-like rootstock, the plant produces short, erect stems, 3” to 6” inches long leaves, set like a trap, and small white flowers on short flower stalks.
In addition to being hinged and toothed, the leaves also have tiny hair on their inner surfaces.
As soon as an insect comes in contact with these hairs, they send a signal to the plant.
As a result, the plant gets ready to close the leaves.
However, the trap closes only when an insect comes in contact with the plant the second time, within about 20 seconds after the first one.
Due to this characteristic, the tiny leaf hair is also called ‘trigger hair’.
In addition to the unique capabilities, the plant also has a distinctive appearance and when planted in a garden, it never fails to capture the attention.
While Venus fly trap is an interesting plant, it is also highly demanding and a lot of people struggle to keep it alive.
Many gardeners complain about their Venus fly traps turning black and dying even though they take good care of it.
Why Do Venus Fly Traps Turn Black?
The primary reason the traps of Dionaea Muscipula plants turn black and die is that they have reached the end of their lifespan.
The traps of the plants are short-lived, with each trap only living for about three months.
However, in healthy plants, the dead leaves get replaced with the new ones.
As long as your Venus fly trap is producing new growth, there’s no need to worry about the traps turning black and dying.
It’s a natural process.
But, if your plant is turning black and not producing new growth, it could be due to any of the following reasons:
Unfavorable Growing Conditions
Unlike most other plants, Venus fly traps require poor soils, in terms of nutrients.
They also do not need fertilizers.
These plants fulfill their nutrient requirements from the insects they capture.
Growing a Venus fly trap in regular potting soil or amended soil can cause its leaves to turn black.
To ensure healthy growth of a Venus flytrap, choose pure peat moss or long-fiber sphagnum moss and make sure it is aerated with silica sand or perlite.
Another potential reason for a Dionaea Muscipula turning black is the use of water with a high concentration of TDS (total dissolved solids).
Just like succulents, Venus flytraps like bright light and even full sun.
Growing them in shaded locations will also cause their traps to turn black more frequently.
If you have recently bought a new fly trap plant or have shifted it to a new location, these could also be the potential reasons behind its leaves turning black.
This is a phenomenon known as ‘repotting stress’.
Venus fly traps, like many other houseplants, need time to adjust to its new environment and/or location.
Just give it time and take good care of it and your plant will soon be back to normal.
It is common for Venus fly traps to turn black and fall off the parent plant near the beginning of the cold weather.
If this is the case with you, don’t worry – your plant is preparing for dormancy.
The dormancy period of Dionaea Muscipula typically lasts from November to February, but it could vary depending on how long and severe the winter season is in your area.
Eating a Big Insect
If the wings or legs of an insect are sticking out of a trap, it’s too big for your plant and can cause it to turn black and die.
To be able to digest prey, the leaf trap of Dionaea Muscipula needs to get completely closed.
If anything prevents the trap from sealing properly, it can cause problems.
Turns out overeating isn’t only problematic for humans – it can create health issues for plants too.
If you have been feeding all the traps of your Dionaea Muscipula plant, the plant may have been overfed.
The digestive process of the fly trap plant takes a lot of energy.
When provided with a lot of food, the plant intentionally causes its traps to turn black and die in order to conserve energy and then later use it to produce new growth.
Since insects are the primary source of nitrogen for Venus fly trap plants, overfeeding can lead to an oversupply of nitrogen, which in turn causes the death of the traps.
How To Control Or Deal With a Venus Fly Trap Turning Black?
The right way to deal with a Dionaea Muscipula turning black and dying depends on what’s actually causing it.
Here’s what to do to deal with the potential causes discussed above:
Unfavorable Growing Conditions
Make sure the soil is nutrient-poor and not amended.
Use sphagnum peat or pure peat moss.
With regards to watering, you should either check your tap water for its TDS level with a TDS meter or use distilled water, rainwater, or reverse osmosis water.
In order to be safe for carnivore plants, the TDS level of tap water has to be 50 parts per million or less.
Lastly, make sure your fly trap plant is getting enough light.
To prevent or minimize repotting stress, only shift your plant to a different location immediately after the end of the dormancy period i.e. in February or March.
If your plant is suffering from stress due to a change in the environment (common with newly bought plants), just give it time, love, and care, and it will adjust to the new place.
To speed up the process, plant it under full sun, outdoors – the plant does much better outdoors than in a terrarium.
There’s nothing you can do if your fly trap plant is losing leaves due to dormancy than to wait for it to end.
Eating A Big Insect
If the plant has captured a big prey, leave it alone.
Let the trap turn black and die because it will be replaced by new traps.
However, be careful with feeding to prevent this problem from recurring.
The foods should be about 1/3rd the size of the trap.
Stop hand-feeding your Venus fly trap for a month, so it could recover.
If it needs food during this time, it will catch the prey on its own.
Hand-feeding is resumed once the new leaves are mature.
However, only feed 1 to 2 traps of a plant, once a week.