Basic Houseplant Care: Water
Did you know that incorrect watering is the number one cause of houseplant death? Most people know that if they forget to water their plants 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 and overwater them, their roots can actually rot, leading to the eventual loss of the plant, as well.
Roots need a combination of water and air in order to function properly. Chronic overwatering creates a situation where the roots effectively 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 also 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, whose main growing season is winter to spring — a reminder to always do your research!)
- If you’re not sure how much to water, start by erring on the side of too little water; this is much easier to correct than overwatering.
- If your pot is small enough to lift, get acquainted with how light it feels when it is dry, as opposed to how heavy it feels when it is well watered.
- Don’t be afraid to get your fingers into the substrate to see what is going on underneath. It’s hard to assess how much moisture is inside a pot from visual cues alone.
- And finally, test how moist your substrate is before watering!
General Water Concerns
Some plants are particularly 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, as well. Room temperature water is best, as cold water can shock the roots. (Please do not water orchids with ice!)
Water on Foliage
Be careful when it comes to wetting your plant's leaves. African violet leaves are notorious for responding poorly to moisture sitting directly on their leaves, which is why you often hear advice to water them from the bottom. Similarly, succulents and air plants can also rot near the base of their leaves if they are left too wet.
Although raindrops clearly fall onto plants' leaves in nature, our homes often have far less air circulation to help wick this moisture away, which can cause issues if fungi or bacteria are able to take hold. That said, this is generally only a problem if the issue is chronic. In fact, if you are able to provide a bit of air circulation, many foliage plants love getting an all-over shower from time to time. It's good to note, however, that chlorinated or fertilized water can leave white markings on your plants’ leaves. This is often present when you bring them home from the garden center, but you can usually clean those marks off with a soft, damp cloth and non-chlorinated water.
Water Needs Explained
Your plant will often come from the nursery with a tag that has simple water instructions. Here's a key to decoding a few of the terms and phrases that you might encounter on a plant tag.
"Medium Water:" Generally, 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. This can be tested by simply putting a finger into the substrate. Alternately, you could invest in a moisture meter. Plants that like this amount of water include aroids (philodendrons, monsteras, pothos, etc.) Chinese Evergreens, Tradescantia, and many other leafy plants.
"Keep Moist:" 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 every day. If that seems too high maintenance, you can try a terra cotta water spike (Plant Nanny) to help. Plants that enjoy consistently moist soil include many Ferns, Calatheas, Marantas, and Alocasias.
"Provide Bog-like Conditions:" 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, as these plants are very sensitive to minerals.
"Low Water/Drought Tolerant:" 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 next-to-none, as in 5-6 times a year.
- "Natural Epiphyte:" 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.
Recognizing the symptoms of overwatering is important, especially because these signs can sometimess be confused with other conditions. With a little bit of common sense and a few tricks, though, it's not too hard to determine what the cause of a plant's issue is.
First, it's important to realize that if your plant is overwatered, it is likely to demonstrate more than one symptom, and that these are more likely to show up young leaves first. While a plant's leaves turning yellow or brown or dropping off could be an indicator of many conditions, if the issue is overwatering in particular, you will often see yellowing throughout the whole leaf — or sometimes on its sides. You might also notice what’s called edema, which is a condition when leaves blister or show lesions or indentations. If you realize that new leaves are showing these symptoms, you are almost certainly overwatering.
Wilting — while a sign of underwatering — can actually indicate the opposite. If you aren't paying close attention, it's easy to think "my plant is wilting" and water it in a panic when this may, in fact, be the original problem. If your plant is wilting, always test the soil and make sure it isn't moist before watering. Otherwise, you might make the problem worse!
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 the roots are mushy or slimy, your plant has definitely been getting too much water. It's important to note that overwatering doesn't just boil down to your watering schedule. Stagnant water trapped in a pot or drip tray could be causing the substrate to remain oversaturated — especially if you are using a potting mixture that retains too much moisture for your plant. Similarly, planting even a water-loving plant in too big of a pot can lead to symptoms of overwatering! A plant cannot take up any moisture from soil that it has yet to grow roots into, so a large volume of wet, rootless soil can cause issues with rotting and stress.
Fixing the Problem
Once you realize that your plant is receiving too much water, take it easy until the plant has a chance to dry out somewhat. If the soil is severely moist, it might be best to remove your plant from its pot and let the soil air-dry. In the case of root rot, you can cut back to where the roots are healthy with sharp, sterilized garden clippers, being sure to clean them between each cut.
While you have the plant out of its 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 blog post on substrate.) When repotting your plant, be sure to select a pot that is appropriate for the size of your healthy root mass — one where the roots can quickly colonize the soil and prevent any moist pockets from forming.
Once your plant is trimmed, dry, and potted back up, take it slow with watering, and go light; in time, your plant should recover.
Underwatering is generally easier to diagnose than overwatering, and thankfully, it is also easier to address! In contrast to the inverse condition, underwatering usually affects older leaves sooner — and to a greater degree — than younger ones. Leaves may dry out, especially near the base of your plant, and you may see the soil pulling away from the edges of the pot. Curling leaves can also be caused by too little water, although be aware that can also be a sign that your plant would like higher humidity levels. If your plant wilts or faints but perks up after watering, that is a pretty clear sign that it would like more water. 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.
Fixing the Problem
Sometimes, the fix is as simple as upping the frequency of your watering schedule or watering your plants more deeply when you do. Get into the habit of checking on your plants often, especially in times of high heat. Some people keep track with a watering app, calendar, or journal. To make it easier to know when the houseplants in your collection need water, you might also consider grouping them together based on their watering needs, or keeping the plants that need the most water closest to your water source or in the highest traffic areas of your home where you are more likely to notice their signs of stress.
Other times, plants can’t access water for reasons that are best addressed by changes apart from your the duration and timing of watering. If a plant is root-bound, its roots can get in their own way and keep your plant from taking up sufficient water. In this case, consider rehoming your plant into a (slightly) larger pot. Alternately, if your substrate is old or compacted, water might be flowing down the side of the pot instead of permeating the soil. In this case, it might help to give the entire root ball a deep soak and seeing if this helps address the issue before trying to refresh the soil. 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, as the tannins may help the roots be able to absorb water better again.
Watering can be a tricky thing to master, but with patience and a willingness to learn from your experiences, you are sure to find a rhythm that works for you and your plants!