Watering House Plants Guide

How often should I water my plants?

How often should I water my house plants? Is a frequently asked question we receive. To answer this you need to understand that "Without water a house plant must die" - watering can with white backgroundThis is a fundamental principle of all plants, it's especially important with house plants as they do not have access to natural sources of water, and therefore depend completely on us to get it right. Most plant death is actually caused by too little water... or in some cases too much. It's a fine balancing act and this guide will help you understand how to get it right.

When to water houseplants?

House plant's are not very keen on strict routine. Yes, you may hear Beth saying she waters all her plants heavily every Sunday morning without fail, or Mike might swear his success is down to watering sparingly every Tuesday and Friday evening. However the fact remains that often such routines are unlikely to work long term and are only setting you up for problems later on. Each plant has their own likes and dislikes when it comes to watering, even two plants of the same type would have differences. A group of houseplants which all have different watering needs by Robin BerthierFor example their location and their size will vary and effect how much water they need. So how do you know when to do it?

Unfortunately the answer to this usually comes down to experience and practice. There isn't a hard and fast rule to follow, it's a simple case of observing your plant, and interacting with it. By "interacting" we mean touching the soil surface and just below that to see if it is moist or dry. If it's not too big or heavy you can also pick it up; a pot or container which is heavily saturated with water will be much heavier than a pot which has completely dried out. There are also instruments you can buy which beep or light up when it's time to water again.

Of all the methods and tricks people suggest the weight of the pot is by far our favorite one. Once you've done it a few times you will "just know" by it's weight how much water is left accessible for the plant and you will be able to gauge if it needs to be left alone, or if it needs a top up or a soaking.

How much to water?

Look for your particular house plant in our Hub section of the website to understand its individual watering needs. When you have understood this, there are a few other things to consider because lots of different factors can influence how much the plant uses and therefore the time needed between watering's.

The plant itself

If the plant has fleshy thick leaves it's been naturally adapted to receiving less water, cacti and succulents for example. Too frequent watering here and you will be increasing the chances of rotting. On the other hand if the plant's leaves are thin or numerous then it will have less tolerance for under watering and will need more frequent watering.

The time of year

There is less light in Winter and the temperature is cooler. This means the plant slows down because photosynthesis is less effective. Providing the room isn't excessively hot you may be able to reduce watering to just once or twice a month over the Winter months.

The environment

As the temperature and light intensity goes up so does the need for water. An increase in both of these variables results in a more effective level of photosynthesis which in turn needs more water.

The surrounding humidity

Plants which are in very humid locations will need less water than those in dry environments.

The size of the plant pot and the material it's made of

As a general rule a large plant in small pot will need much more water than a small plant in a big pot. This is because if the roots are filling the pot, there is less capacity for the soil to hold water (because the roots are taking up the space). The opposite is true when the plant is small but in a large pot, in these circumstances much more water can be held by the soil so less frequent watering is needed..

Plant's in clay pots compared to those in plastic ones, will normally need more water because the clay is porous and water is wicked away from the soil in the pot. Finally If you apply a mulch around the plant water will remain in the pot for a longer period as the mulch prevents the soil surface drying out as quickly.

Signs from the plant to look out for

Sometimes it's easy to know when to get the watering can out as a number of houseplants are rather clever and tell you when they want water. The Peace Lily in the photo below for example is very obvious.

Two pictures of the same Peace Lily, picture on left shows it needs water, the picture on the right has enough water

The picture on the left is the Peace Lily telling you it really needs water, the one on the right shows its now got plenty. Most however don't give such clear signs, but there are a few subtle hints you might be able to pick up on.

Signs that its had too little water

  • Leaves become limp and wilted. Sometimes faded or translucent.
  • Flowers fade quickly or fail to actually bloom.
  • The oldest leaves on the house plant start to fall off.
  • Leaf edges become brown and dry.

Signs that its had too much water

  • Leaves become limp and wilted.
  • Flowers become moldy.
  • Both old and newer leaves on the house plant start to fall off.
  • Leaf tips become brown.

Under-watering and over-watering cause very similar warning signs in house plants

Ahem. If you have read the two lists above you might be forgiven for thinking we have made a mistake and copied the same signs into each. Unfortunately it's no mistake, frequent under watering and over watering cause very similar warning signs in house plants! Even the Peace Lily example above sometimes isn't always that clear. If the Peace Lily has had too much water it also flump's over a little bit, which the novice may assumes means more water is needed, and before long he or she is trapped in a cycle of continuously over watering.

It's not all doom and gloom though, if you ever see any of the symptoms listed above you will just need to rely on other methods to judge (such as pot weight / touching the soil / common sense etc) and make an educated decision as to which type of watering mistake is causing the problem, and adjust accordingly.

What time is best to water?

What ever time suits you! Well this is mostly true, a lot of house plants don't mind if you water them in the morning, afternoon or evening. However as a general rule its best to avoid watering any plant in the evening when it involves wetting their crowns or exposed stems. The idea is that if you do this, the water sits on the plant and when the temperature drops at night it can encourage plant rot or diseases. If you watered that plant in the morning, by nightfall the water should have subsided or evaporated from the crowns / exposed stems.

How to water

There are three main ways to water. Sometimes it's about what is most convenient for you, other times it's simply about preference. However it's almost always best to water heavily once, then wait until the soil starts to dry out rather than little and often.

Watering Can Method

This just involves watering from the top and allowing the water to filter through the pot by gravity. Although it's very quick it's less accurate than the other two methods below and so it's always best to have the pot sitting in a container or drip tray to catch any water that comes out of the drainage holes. If your container has no drainage holes for excess water to escape from then you have no choice but to use this method, but be very careful you don't over do it!

Bottom Watering Method

Watering plant using the Bottom Watering MethodThe plant pot is sitting in a drip tray and you just fill the tray up. Eventually the water will be drawn up into the dry root ball. If the drip tray is quite small you may need to do this a few times until no more water is drawn up. Be sure to tip any excess water that is still in the tray away after half an hour to prevent rotting.

Immersion Method

You need to fill a lager container such as a washing up bowl, and then lower your plant pot into the water just so the water level reaches the top of the pot. Bubbles will appear on the surface, and when they stop (after a minute or so) the root ball will be fully saturated with water and you can remove the pot from the water. This method carries a risk of spreading diseases or pests if you are doing multiple plants in the same water. Make sure your plants are healthy, or ensure the sick one goes in last.

What water to use

The best water you can use on your house plants is the most natural - Rainwater or bottled water. However both of these options can be impractical or expensive in the long term, so tap water is the most commonly used type of water. In the majority of situations tap water does not cause any problems, however if you live in a soft water area you need to carry out an additional occasional step to avoid issues. This is because soft water contains salt that will build up in the soil which will eventually effect the natural transfer of minerals and water into the roots.

To avoid this happening "flush" the pot once every couple of months. This just involves pouring in water to wash the salt build up out of the drainage holes. Be sure to provide fertiliser as you will also wash out nutrients in addition to the salt by doing this.

Watering troubles

Watering is normally a quick and painless process, but sometimes there is something wrong with the soil which causes issues:

Water won't penetrate the surface

This is caused by a very dry surface soil. You don't typically get this unless your potting mix contains high levels of clay, for example if you have used garden soil instead of potting compost. Or the soil is completely bone dry. The solution is straight forward however, just prick the surface with a fork or small trowel to break it up a little, then try watering again.

Water runs straight out of bottom

This is almost always caused because the soil has dried out completely. This results in soil pulling away from the edges of the container creating a clear channel for the water to drain through, and the soil therefore does not have a chance to grab any of the water that is quickly passing by. The solution is to follow the Immersion watering method above, if that isn't practical you can try Bottom watering.

Also on OurHousePlants.com

Credit for the houseplant group photo to - Robin Berthier


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