How much water should I give my plants?

If you’re new to gardening, one of the hardest things to gauge is how much water you should be giving to your plants. You can often feel that you’re playing a guessing game, and that nobody you ask is completely straight with you or can give you a definitive answer.

The truth is, knowing how much to water your plants isn’t difficult, and you can figure it out for yourself, once you’ve learnt a few simple principles. I promise you, if you take 3 minutes to read this article and apply the information within it, you’ll be able to proceed with much more confidence, regardless what plants you own.

As a starting point, here are the golden rules of watering:

1. Touch test the soil
2. Take weather into account
3. Take position into account
4. Different plants need different amounts of water (keep reading to see an explaination of how to know which plants need more water and which need less, which you will be able to apply yourself.

So let's get started, shall we?

Touch test the soil

In order to decide whether or not to water plants, and how much water to give them, start first of all with a touch test of the soil at the top of the planter or plant pot.

As a general rule (and these are very general guidelines so there will be exceptions to this), soil should be moist and springy to the touch, but not wet. If the soil is wet, you might need to drain some of the water from your plants in order to give the roots chance to breathe. It is possible to overwater plants, and probably one of the quickest ways to kill them.

On the other hand, if the soil is very dry and cracked to the touch, you almost certainly need to give your plants a good watering, and if the pot is small enough, it may even be best to try and soak the soil thoroughly, then allow it to drain, if the soil is very dried out.

Alternatively, you could buy a moisture gauge that will tell you the humidity of the soil.

Take weather into account

Now I know this sounds obvious, but more than anything, you need to be able to respond to changes in the weather with your plant watering. The second the sun appears, you really do need to up your watering game or your plants will show visible signs of wilting. If you know it’s going to be a really hot day, water the plants first thing in the morning to give them a head start.

Like humans, plants do consume more water when it’s hot, so you will need to make sure that this pre-emptive watering is sufficient, and check your plants twice a day if you can when the weather is especially hot or dry. You may find that you need to water them more than once a day (don’t worry though, British Summertime is not renowned for being super hot and sunny, so you won’t have to do this for many days in a row. 😉

Take the plant’s local conditions into account

The amount of sun and shade, container size, shape and material can all influence the amount of water you need to give your plants. In all pots, drainage is extremely important. With a few exceptions, your planter simply must have drainage holes for excess water to run through. Not having drainage is a quick and sure-fire way to drown plants.

If a container is positioned in the shade, it’s likely to require less water than one that is placed directly in the sun and vice versa.

If a container is made of hessian sac or a woven fibre, it will certainly need more frequent watering than one made of terracotta, which in turn is likely to need more watering than one made of plastic (terracotta is more breathable than plastic). Larger containers retain moisture better than smaller ones. Plant pots with one individual plant in are likely to need a great deal of water indeed, as they don’t have the moisture of other plants around them. 

Different plants need different amounts of water

The secret of knowing how much to water your individual plants is knowing just a little bit about them in the first place. 

Very often, plants come with an information tag that tells you a little about the grower and some outline plant information. Look for the origin of the plant. Where in the world does it come from? Is it from the tropics, is it Alpine, or is it from a desert? Is it Mediterranean or does it thrive in swampy surroundings?

Very often, knowing this small nugget of information is all it takes to know how much to water your plants because it tells you the humid conditions that you will need to replicate in order for it to thrive.

• Swamp dwellers, e.g. Hostas or Lilies. Plants with thin or large leaves typically need more water and less sun than plants with waxy leaves, like succulents. Plants that do well in shade often also need more water to thrive (think about the conditions you’re likely to find them in in the wild). They will do best if the soil is always damp to the touch.
• Evergreens and grasses, e.g. Carex grasses and conifers, need very well-drained soil and soil should be moist, but springy to the touch.
• Brightly coloured flowers, e.g. Dahlia and Petunias, generally need quite a lot of water. In hot weather, they will need watering twice a day. 
• Fruit and vegetables Need a hell of a lot of water. Like most things, they need more water than you think. They benefit from watering twice a day, even when it isn’t hot. The more you water fruit plants, the bigger and jucier the fruit it produces will be.
• Succulents, e.g. Echevaria, need very little water and the soil should generally feel dry to the touch – but thankfully, they are reasonably hard to kill from underwatering.