Watering your houseplants

Learn about under-watering, over-watering, frequency, and drainage.

Getting it right

Water is a fundamental need for plants. They need it to make food for energy, and to stand up tall. A plant absorbs water through its roots, and transports it up its stems to its leaves. When a plant has enough water, the water pressure inside makes its stems and leaves strong and sturdy. If a plant isn’t hydrated enough, the water pressure drops and the stems and leaves will wilt.

Houseplants don’t have access to natural sources of water, so they rely on you to give them the water they need. It can be tricky to get the watering right – when a houseplant dies it is usually because of a disrupted water balance. You might think that you’re not watering your plants enough, but plants are more inclined to die from too much water than from too little water.

Under-watering

So your plant is wilted. If a plant is dehydrated, the cells in the plant will shrink and the plant will look wilted. The symptoms of under-watering are very similar to those of over-watering though, so always check the water balance before you add water your plants. Feel the soil. If it feels dry, it’s likely your plant is low on water. For many plants, this is easily solved. Give it a bit of water and it will form back to its original shape in no time.

Over-watering

In contrast to under-watering, over-watering is easily fatal and occurs much more often. Too much water in the soil causes the roots to rot, which is often an irreversible process. In addition to root rot, the root hairs that absorb water will die out from too much water and the accompanying lack of oxygen. The result is that the plant cannot take up any water, and the plant will wilt. This is why a plant that is suffering from over-watering often looks similar to a dried out plant; because it’s dying from dehydration!

Drainage

To ensure that excess water can leave the soil, drainage is very important. Always make sure your plant pot has holes in the bottom. If you want to use plant pots that don’t have holes, leave the plant in the grower’s container when you place it inside a planter. The grower’s container also has holes in the bottom, so that the excess water can leave the soil. 30 minutes after watering, remove excess water by taking out the grower’s container, and emptying the planter.

Frequency

Alright, this is where it gets a little tricky. Unfortunately, there are no easy-to-follow rules when it comes to the frequency of watering your plant. How often your plant likes to be watered depends on the size of the container and the plant, the amount of light it receives, the plant species, the temperature, the season, the air humidity and the soil composition. Because of this, it’s important to get a feel for each of your plants.

Some general rules of thumb:

When you’re considering watering your plant, first feel the soil. Stick your finger into the soil until the first knuckle, and if no soil sticks to your finger, it may be time to water the plant.
If your plant is getting a lot of light, its metabolic processes will be more active. This results in a larger water uptake, and the plants will need to be watered more often. The opposite is also true: if you move a plant to a darker spot, you will need to give it less water than before.
Succulent plants and cacti don’t need a lot of water. These plants are adapted to grow in deserts, and will be fine if you don’t water them for a few months. It’s easy to over-water these plants and the damage is irreversible, so be careful. Less is more.
If you use terracotta pots, you will need to water your plants more often, because the water evaporates through the pores in the clay.
If you have a group of plants placed closely together, the plants on the outside will dry out more quickly than the ones on the inside.
A smaller pot or container dries out more quickly than a larger one.
In a colder season most plants are in a dormant state. You can water them a lot less than you would in the summer.
If you use air conditioning or heating, the air humidity will go down. Water in the soil will evaporate more quickly, so you will need to water more often.

Every plant keeper knows how sad a wilted plant can look. You can prevent this by getting the water balance right. Other factors, like light and fertilizing, are also important, but get a feel for how much and how often to water your plants, and you will develop a green thumb in no time!

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