Venus flytraps require moist soil at all times. The water used for water a Venus flytrap must also be extremely pure. For the purposes of flytrap growers, this basically means ‘distilled’ water, reverse osmosis water or properly collected rain water. But more on that later. The very first thing to remember is: NEVER, EVER let the soil completely dry out.
The most common way of watering a flytrap is to simply keep it sitting in a shallow tray of water. There are two things to take into account when using a water tray. The first is that the water level should only be a half inch to an inch high. While flytraps do love moist soil, they also need their roots to breath. Keeping a flytrap in deep water for extended periods can cause poor root health and the death of the flytrap. But deep water is fine every now and then and it is for this reason that going on vacation is no big deal. Just leave the plant sitting in a couple inches of water (depending on the length of your absence) and it will be happy. The second thing to take into account with a water tray is that, the wider the tray, the more water it will lose to evaporation. This is especially important in the hot summer months. More evaporation means more refilling due to evaporative water loss. Conversely, choosing a tray that hugs the pot will reduce the volume of water and will require more refilling as well. Neither of these options is really a huge problem, but its just something to keep in mind.
There are three practical sources for obtaining water that is pure enough to water a Venus flytrap. The easiest is to get a two gallon jug (the rectangular kind with a spigot) of distilled water from the grocery for less than $2.00. If you only have a handful of flytraps, this should easily last a month or two. Cost-wise, this is the equivalent of keeping a few goldfish. Keep in mind that you should only buy ‘distilled’ water and not ‘drinking’ water (which often has salt added) and certainly never ‘mineral’ water. Even though the amounts of salt and minerals in the latter two types of water are minuscule, they will slowly build up in the soils and kill your flytrap.
Another source of water is rain water. The problem with this is that the rain water must be very clean. Collecting rainwater from roof run-off is usually a recipe for disaster for your flytraps. First, typical asphalt shingles contain many chemicals and also shed particles. Second, if there are any trees overhanging your house, then your roof will accumulate all kinds of organic debris (as seen on vehicles which also park under trees). So, IF you want to collect rainwater to use for your flytraps, the safest way to collect rainwater is as run-off from plastic or directly into plastic containers.
Finally, most Venus flytrap and carnivorous plant nurseries use a third option: a reverse osmosis (r.o.) system. These systems can be bought for between $100-$200 and installed under a kitchen sink or anywhere with a water source and drain. Installation does require installing an in-line valve and tapping into the drain pipe, so this won’t be D.I.Y for everyone. But, even small systems are capable of producing 50-gallons a day and usually have a 3 gallon storage tank included, so they can provide plenty of fresh , pressurized delicious water for drinking as well.
So if you have only a few plants, buying distilled water may be your best bet and is a completely sustainable method to water a Venus flytrap. If you develop a habit and your flytrap collection gets serious, then an r.o. system may be in your future.
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