WHEN TO WATER
Perhaps the most confusing aspect of houseplant care, and the one I’m asked about most often, is how much water to give a plant. Watering is your most important job when caring for indoor plants and also a surefire way of killing them. And it’s not just forgetting to water that’s bad; you can kill them with kindness, as excess soil moisture rots the roots. So, how much water? Well how long is a piece if string? The amount of water each plant needs is governed by lots of factors. Rainforest plants need more water than desert plants. Bigger plants need more water than small ones. Plants growing in hot rooms need more water than those growing in cool rooms. So, there’s no simple answer, but if you know what to look for, then it’s easy to keep your houseplants happy.
A good place to start is recognizing the signs that your plant is thirsty and the most obvious is wilting. Plants use water pressure to keep themselves upright, so when they become limp, then there’s insufficient water in the soil. A few plants also wilt when too wet – African violets and streptocarpus famously so – causing concerned owners to apply even more moisture. However, these are exceptions. A good way to tell the difference is to lift the plant up and feel the soil. Droughted plants are light-weight and the soil feels dry to the touch.
Ideally, do not let your plants wilt before watering; you want to catch them before they reach the desperate stage. Start by watering once a week, thoroughly soaking the soil with a watering can. Try to do so on the same day each week – routine will help you remember. After a month, you’ll start to appreciate whether weekly watering is sufficient. During summer, you may need to increase to twice weekly, while in the depths of winter, once every ten days may suffice. Over time, you’ll get a feel for your own plants and their needs. You’ll identify the prima donnas – peace lilies I’m talking about you – needing extra attention, and those such as cacti and aloe that handle drought with aplomb. And if in doubt, feel the soil!
Dr. Ross Bayton
Heronswood Assistant Director
Photos by Ross Bayton