Down the Garden Path: Water basics for houseplants

Houseplants cheer us up when it’s wintry outside, but sometimes we don’t have good luck growing them. The solution could be as simple as water! More houseplants die from under- or overwatering than from any other reason. Let’s start with the basics to make sure your houseplants are getting the right amount of water.

Pick the right pot

You can grow houseplants in any container that drains water. However, if the pot is too large, the potting mix can hold too much water because the plant is too small to use it quickly. If the pot is too small, the plant’s roots can become crowded and not able to take in enough water. Both problems can be solved by repotting. A rule of thumb is for the pot to be about 1-2 inches larger than the plant’s root ball.

Use the proper potting mix

Make sure your houseplants are growing in a lightweight potting mix that easily drains water rather than heavier garden soil. Potting mix is also disease and weed seed free, unlike some garden soils. As a bonus, most mixes contain fertilizers that last for several months.

Water the way it needs

Many people water “by the calendar” instead of whether the plant needs water. Underwatered plants usually wilt from the top and the leaves may become crispy or brown at the edges. A waterlogged plant will also wilt, with yellow or browning leaves that may fall off. As you can see, plants that are underwatered can look a lot like ones that are overwatered. How do you tell the difference?

The solution is to look at the potting mix. If the mix begins to crack and pull away from the sides of the pot, you are waiting too long to water. If the mix is always dark and slimy looking, you are overwatering. When is it time to water? Look at the mix, which becomes fluffier and has a lighter color as it dries; pick up the pot to see if it’s lighter than after it has just been watered; check for dryness with your finger an inch or so below the surface.

You can water your plants from either the top or the bottom of the pot, using ordinary tap water. From the top, add water until it starts to drain. If the water hasn’t stopped draining in about 30 minutes, you may need to add more drainage holes to the pot. Also remove any water in the pot’s saucer. If you are watering from the bottom, set the pot in a container or sink with a few inches of water. You will know that the pot is watered when you see that the top of the mix is dark.

Don’t forget temperature, light and humidity

Moving plants around your house can change their water needs. A plant in a warmer location will use more water than a plant in a cooler spot. A plant that is exposed to more light will use more water than one getting less light. Heated houses in the winter often have low humidity. You can increase the humidity by keeping your plants on top of a pebble-filled tray of water.

Follow these water basics for success with your houseplants any tome of the year. For more information on caring for houseplants, see extension.illinois.edu/houseplants.

• Sue Styer is a certified Master Gardener and Naturalist volunteer with University of Illinois Extension serving DuPage, Kane, and Kendall counties.