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Did you know that incorrect watering is the number one cause of houseplant death?
Most people know that if they forget to water for too long, their plants will dry up and eventually die. What many people don’t realize is that if they give their plants too much love by overwatering, the roots will rot and that can lead to death too!
Roots need a combination of water and air in order to function properly. Chronic overwatering creates a situation where the roots basically drown, then rot. Of course, ongoing underwatering causes drying up, desiccation, and root death.
It’s vital to find out, generally, how much water your houseplant needs and then adjust from there. Your specific circumstances will all alter the amount of water needed. Depending on your light, heat, pot type and size, drainage, humidity, and substrate (potting medium,) your water needs will change. You’ll always have to watch the plant and see what seems best.
Be aware that water needs change with the seasons. For most plants, their growing season coincides with warmer weather and that’s when they need the most water. Most plants slow down their water uptake in cooler weather and are extra susceptible to being overwatered by well-meaning caretakers who don’t notice the change. (One notable exception is aeoniums -- their main growing season is winter to spring -- so always do your research.)
Test how moist the substrate is before watering!
Some plants are extra sensitive to chemicals and minerals that are found in tap or well water. In fact, all houseplants can benefit from the use of filtered, distilled, or rain water. A simple charcoal or drinking water filter is all that is needed. Examples of sensitive plants are: carnivorous plants, spider plants, calatheas, and dracaenas.
Pay attention to the temperature of the water. Room temperature water is best, cold water shocks the roots. (Please do not water orchids with ice!)
Be careful about getting water on foliage. Of course, in nature rain falls directly on leaves, but in our homes sometimes the air doesn’t circulate enough. Leaving foliage wet too long can allow fungus or bacteria to get a hold.
Chlorinated or fertilized water can leave white markings on your plants’ leaves, which is what is often present when you bring them home from the garden center. (You can usually clean those marks off with a soft, damp cloth using non-chlorinated water.)
African violet leaves are notorious for responding badly to getting wet, which is why you often hear advice to water them from the bottom. Succulents and air plants can easily rot near the base of their leaves if left too wet.
However, if you do have good air circulation, many foliage plants love getting an all-over shower from time to time.
Your plant will often come from the nursery with a tag that has simple water instructions. But what do those mean? Let us explain!
This means that you should wait for the top layer of substrate to dry out before giving the plant more water. How deep the dry layer should be, depends on the size of the pot. On a small pot, let ¼ to ½ an inch get dry. On a large pot you should wait for 1 to 2 inches to dry. Test this by simply putting a finger into the substrate, or you could invest in a moisture meter. Plants that like this amount of water include aroids (like philodendrons, monsteras, pothos,) Chinese evergreens, Tradescantia, and many other leafy plants.
Plants that enjoy consistently moist soil include many ferns, calatheas, marantas, and alocasias. It’s important to understand that this doesn’t mean water-logged or oversaturated. The roots still need access to some air. In order to provide the right amount of water, these plants should be watered a little bit, daily. If that seems too high maintenance, you can try a terra cotta water spike (Plant Nanny) to help.
Some carnivorous plants (including Venus fly-traps, sundews, and some pitcher plants) enjoy lots of moisture. For these, you can let their pots sit in one to two inches of water to create bog-like conditions. Always make sure to use distilled, filtered, or rain water, these plants are very sensitive to minerals.
Succulents and cacti need very little water. Watering is still necessary, it’s just very important to let the substrate dry thoroughly between deep waterings. On average, succulents need somewhat regular watering, whereas cacti need almost none, as in 5-6 times a year.
Epiphytes (plants that grow on trees in nature, like orchids and bromeliads) have special watering needs. Many should be soaked for a short time when dry, then allowed to drip dry, but please do research for your specific plant.
Beyond simply watering too often and too much, there are other situations that can lead to overwatering symptoms. Stagnant water is a big cause. This could be water that gets trapped in a pot or water that is left inside a drip tray, both of these scenarios can cause the substrate to stay oversaturated. Using a substrate that retains too much moisture could also lead to overwatering issues, even if you aren’t watering very often. This is due to there not being enough larger pieces relative to peat moss or coir product. Even planting something in too big of a pot can lead to too much water being retained, and eventually overwatering symptoms as well.
One thing to keep in mind is that signs of overwatering often show up on younger leaves more readily than older ones. You may be overwatering if you realize that new leaves are turning yellow and falling off.
Overwatering can be confusing because one big sign is... wilting! People usually think wilting means a plant needs more water, and so they give it more, which makes the problem worse when it was caused by too much water. So remember: if your plant is well-watered and yet simultaneously wilting, that is different than wilting from a lack of water.
Other signs include leaves turning yellow or brown, which can sometimes be seen throughout the whole leaf or other times just on the sides. You might also see what’s called edema, basically that’s a condition when leaves blister, get lesions, or indentations.
If you suspect that your plant is telling you that it’s been overwatered, the best way to confirm your suspicion is to check the roots. Don’t be shy, gently pull the plant out of its pot and check. If roots are mushy or slimy they’ve definitely been getting too much water.
Stop overwatering! Once you realize that too much water is the issue, you need to take it easy until the plant has a chance to dry out pretty well. It might be best to take it out of its pot and let the soil dry out in the air. In the case of root rot, you can cut back to where the roots are healthy with sharp, sterilized garden clippers. Make sure to clean them in between each cut.
While you have the plant out of the pot, take a moment to assess the situation further. Has the substrate become too compact to allow water and air uptake? This might be a good time to start fresh, maybe even add some aeration to the mix in the form of perlite, bark, or pumice. (For more information on this, look for our upcoming blog post on substrate.)
Once your plant is trimmed and dry, start slow and light with watering it again. Give it time to recover.
There are many strategies for making your watering more consistent. The best plan is to get into the habit of checking on your plants water needs often, especially in times of high heat. Some people keep track with a watering app, calendar, or journal. Consider grouping plants together based on their watering needs. It might also be helpful to keep the plants that need more water closer to the water source or in areas that you spend more time in.
We all know that we tend to underwater when we get busy or distracted, but sometimes plants can’t access water for additional reasons. If a plant is root-bound, often the roots get in their own way and can’t absorb water. Other times, the substrate is old or compacted and the water finds ways down the side of the pot instead of through the soil, leaving the root ball dry when you try to water.
Underwatering usually affects older leaves more than younger leaves (the opposite of overwatering). You might notice leaves curling, although be aware that can also be a sign of too low humidity. If your plant wilts or faints, but then perks up after watering that is a pretty clear sign that it would like more water. Leaves may dry out, especially near the base of the plant. You might see the soil pulling away from the edges of the pot.
If you suspect you might have been underwatering a plant for a long time, take a look at the roots. Underwatered roots will be withered, dead or dying, and dry.
It might be as simple as picking up your watering schedule to give the plant more water, more often. Sometimes, though, if a plant is too dry the substrate and roots won’t soak up water properly anymore. In these cases, it might help to give the entire root ball a deep soak. Always make sure to let the plant drip dry afterwards, you don’t want to overdo it and have an overwatering issue on your hands!
In really bad cases of desiccated plants, it can be helpful to soak the root ball in a very weak black tea, cooled to room temperature of course. The tannins will help the roots be able to absorb water better again.
Watering can be a tricky thing to master, but just keep trying and learning from your experiences. Eventually you’ll get into a rhythm that works for you and your plants!