Water and Watering Houseplants

Water is vital to the survival of all living things. But too much or too little can kill your house plants, so it’s important to know when and how to water.

Push your finger a full 2.5mm (1 inch) into the compost. If your fingertip remains dry then the plant needs water. For plants that like to be kept moist at all times you need only look at the surface of the compost – water as soon as it seems dry and powdery. Succulents and cacti need no watering in winter unless the leaves start to shrivel. If that happens, water only sparingly.


How to water

Top watering means you can control the exact amount of water applied. You simply pour water directly on to the compost. Fill up to the rim of the pot. In winter stop as soon as water begins to drain from the bottom. Never let plants stand in water longer than 30 minutes. The only disadvantage to this method is that too little water leaves the bottom of the compost dry.

Bottom watering takes more time, but the compost does get a really good soaking. Stand the plant in a deep saucer full of water and leave it to soak until the surface of the compost starts to glisten. Allow the pot to drain and then return the plant to its normal home. The bottom watering method is ideal for house plants that dislike to have water on their leaves.


Pots and composts

Three important considerations when it comes to watering are the type of container your plant is grown in, the potting mixture and the water you use.

Pots can be made from clay, plastic, glazed or polystyrene. Water will evaporate far more quickly from an ordinary unglazed clay pot than from the others, and a plant that has been grown in such a pot will need more water.

Plants that need fast-draining compost will have coarse sand or Perlite added to the growing medium. This will lose water more quickly than ordinary potting mixtures.

The ideal water to use is soft water or rain water. Leave chlorine-rich water overnight to reduce its chlorine content. In hard-water areas, use boiled and cooled water.

Water is life and everything and everybody depends on it. Plants need water to fill out their leaves and stems; to transport vital minerals and nutrients contained in the soil to all of their parts; and water is a very important element in the process known as photosynthesis, whereby plants manufacture most of their own food.

A considerable amount of water is lost by plants as they ‘breath’, particularly when temperatures are high and the air is dry. Dry air sucks water from plants, which is one very good reason for keeping the air around them as humid as possible. It is said that the leaves of a Sunflower, for example, transpire as much water on a hot day as a person loses, and a birch tree can suck up hundreds of gallons of water on a summer’s day, to use as a cooling device.

Most house plants prefer to be watered thoroughly and then allowed to dry out a little before they are watered again. If a compost is kept permanently wet, air is excluded and a plant’s roots are unable to function properly.

It is impossible to make generalisations about the amounts of water plants need or the number of times you need to apply water to the plant. Plants are individuals and their specific requirements depend on the size of the plant, size of the pot, the humidity in the room and the time of the year.

More house plants die from overwatering than from any other single cause, so recognizing when your plant really does need water is the vital clue to happy healthy house plants.

How much to water

Water sparingly

Give just enough water to barely moisten the compost. This is suitable for succulents during the winter. It keeps the plant from shrivelling, but doesn’t encourage growth.

Water moderately

Give enough water to thoroughly moisten the compost, but let it dry out between waterings. This suits plants from drier areas during their growing period.

Water generously

Give the plant a good soaking and don’t let the compost dry out much before watering again. This suits vigorous climbers and plants with large leaves and extensive roots.

Watering when you’re away

  • A summer holiday for you could spell disaster for your house plants if you haven’t made careful provision for their watering.
  • Capillary matting is a reliable method of keeping your plants watered. Fill your kitchen sink or a washing-up bowl with water. Lay the matting over your draining board and immerse one end in the water. This method is only suitable for plastic pots, not clay ones.
  • If you have a prize specimen, it would be worth investing in a special wick, that sucks up water from a jar.
  • In summer, plants need regular supplies of water. If you can’t get a friend to look after your plants, here are a few instructions to follow.
  • Sink tougher plants into a larger container filled with moist peat and, if possible, stand outdoors in a shady spot.


Can I use tap water for my house plants?

Yes, but it’s better if you fill a can and leave it overnight. This will allow some chlorine to disperse.

Are self-watering pots a good idea?

Yes, they are particularly valuable for large and expensive plants.

I live in a hard water area; what can I do?lkaline water leaves an unsightly deposit on leaves. Use what is left in the kettle after boiling (and cooling) or the water that comes from thawing out a refrigerator.

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