Venus Flytraps require very pure water. Your tap water is likely to be too high in dissolved solids—minerals and salts—that may kill a Venus Flytrap, possibly within weeks.
Your Venus Flytrap requires consistent moisture and high humidity in order to thrive. If they experience periods of dry soil or low humidity, some of the leaves and traps might brown, yellow, or die off as a way to preserve energy. The plant is usually able to bounce back from a period of drought.
According to Rocket Farms, Venus flytraps need four distinct things to flourish: water, light, temperature, and food. More importantly, these unusual, carnivorous plants require more attention than most people are willing to give.
Do not give a trap any food that is bigger than about 1/3 the size of the trap; larger insects take too long to digest and can cause bacterial rot that kills the trap. It responds to the movement of an insect to avoid wasting energy on consuming non-food sources.
When you dig them up, check out the rhizome, the part between the leaves and the roots that sits just under the soil. If it's white and firm, your plant is alive and well! If it's black and mushy, you unfortunately have a dead plant on your hands.
It is easy to differentiate between a Venus flytrap that is dying, versus one that is entering dormancy. A dying Venus flytrap gives up the ghost fairly quickly. The leaves die completely, and all that remains of the plant is something all mushy and gooey.
Cut off dead flowers with scissors – and in the case of Venus flytraps and pitcher plants, cut off the dead traps if they go black – this often happens in autumn and winter.
In many respects, flytraps should be easy. They don't require fertilizing. They can survive under full sun or fluorescent lights. Unlike so many other houseplants, they can sit in a half-inch of standing water without fear of roots rotting.
And it turns out that if you stick your finger into a trap, nothing's really going to happen. If you move your finger around a little bit to trigger those trigger hairs then the trap will start to close.
As the insect struggles to escape, it triggers even more outgrowths, causing the Venus flytrap to tighten its grip and release enzymes to digest its snack. Each "mouth" can only snap shut four or five times before it dies, whether it catches something or not.
To keep your Venus' Flytrap happy, give it lots of light, sit it in a shallow water tray and only feed it live insects. If you grow your plant indoors, a sunny windowsill is best as these plants love light. Water is also important, particularly in summer when the pot can dry out quickly.
Once a trap dies, a larger one will replace it. Your flytrap may produce a flower in the spring. If you want the plant to continue making traps, cut off the flower. If you allow the flower to grow, it may produce a seed pod in about a month.
Water the Venus flytrap plant with pure water like rainwater, distilled water, or reverse osmosis (RO) water. Don't use tap water or bottled water as it could contain significant minerals that cause death to Venus flytraps.
Light: The first reason why your Venus Flytrap is turning black may have to do with light. The plant needs a lot of sunlight to stay healthy, so if your plant is not getting enough direct sunlight, it may turn black. This is more common in the winter months, when the days are shorter.
Feeding flytraps
If you close too many at once, the plant uses all of its reserves, and the traps begin to blacken. Wait until the traps are fully open and feed just one or two a week. If you're feeding the right amount and the Venus flytrap is turning black anyway, perhaps the problem is what you are feeding it.
Your Venus flytrap cannot use more than half of its traps at one time for digestion. The digestive process takes too much energy from the plant -- it responds by dying back to conserve energy. If you feed a cricket to only one trap and it turns brown or black, that trap may have exceeded its lifespan.
Venus flytraps are perennial, carnivorous plants that can live up to 20 years in the wild. While most of their energy is obtained through photosynthesis, insects provide nutrients that aren't readily available in the soil.
While the Venus flytrap is devoid of a brain, it will hang on to short-term memory if there is enough of a calcium ion boost. Fluorescence spread from one leaf “jaw” to the other. It especially increased at the base of the hair, where there are sensory cells that tell the Venus flytrap when to clamp down on a bug.
The flytrap grows best outdoors as a container or potted plant. It makes an excellent addition to any sunny deck or patio. You may also grow it in a pond or fountain, but keep the crown of the plant above water.
Aphids (Greenfly)
With small plants like Venus Fly Trap and Sundews, the aphids can over winter in the plant and do a lot of damage before the leaves come up. Sometimes you cannot see any insects, but may have tiny white sheddings of their skins, and a sick looking plant. This will be aphids.
Indoors or out, keep the growing medium moist to wet at all times. Remember, these are bog plants. Do not allow the soil to dry out. Water the plant by sitting the base of the pot in a saucer of water for a few hours at a time every few days.
When you put the insect inside the leaves you may need to move it around a bit to help stimulate the trigger hairs. Carnivorousplantstips.com says: "A venus flytrap should be fed four times a year with the plant being fed three bugs per feeding."
If your Venus fly trap is turning black, it's most likely going through completely normal processes. The main reason a trap turns black and dies is that it's simply at the end of its lifespan. Each individual trap on a plant has a lifespan of about three months during which it will catch about 1-4 insects.
During winter they go into sleep or dormancy mode. This is where they stop producing new traps and just chill out. There are good reasons why Venus Flytraps go dormant and these are..... There are no insects to catch in winter!