Water, along with light, is one of the two essentials needed for plants to survive, but it can be a confusing thing to get right.
The short version is: there’s no standard watering schedule that will work for all your plants. It needs a bit of judgement and adjustment, which comes with time, practice, and probably a few plant deaths!.
There are a number of factors that affect how much you should water your plants
1 | Type of plant
This is the most obvious factor, that many will already know. Succulents like aloe vera and cacti need less water than more leafy foliage plants like peace lilies and monstera deliciosas.
A good rule of thumb is that the fleshier the leaves, the more water the plant stores itself (because it’s probably used to drier environments like deserts). Therefore the less it needs watering.
The thinner the leaves – like the paper-thin maidenhair fern or calathea foliage – the more quickly it loses water. These tend to need more frequent watering, and higher humidity too.
2 | Light and location
Darryl Cheng in his brilliant book The New Plant Parent, completely changed the way I thought about light levels, and therefore watering.
The brighter the spot the plant is in, the more water it needs, and the darker the spot, the less it needs.
So two identical plants in two different places in your home will need different amounts of water. 🤯
As Darryl says, a good way to understand light levels is to look at ‘What My Plant Sees’. If it can see lots of sky through your window it’ll be getting lots of indirect, and probably some direct sunlight. If it’s can’t see any sky at all, it’s probably not getting much light.
Even moving a plant a few metres back from a window will drastically cut how much light it gets, and therefore it’ll need less frequent watering.
3 | Season
When they’re not growing vigorously, plants need less water. They grow most during the spring and summer, and slow down considerably, or stop growing altogether in the autumn and winter.
I notice my houseplants’ soil starts taking longer to dry out by the end of September, so I ease back on watering around that time.
4 | Pots
The type of pot your plant is potted into will make a difference to how quickly the soil will dry out. Plastic pots (and pots without drainage, which generally are best avoided!) will hold moisture for longer.
Meanwhile terracotta and clay pots will allow the soil to dry out much more quickly after watering. Swapping a plant to terracotta clay pots, as I’m doing with many of my peperomias, means that the soil dries out more quickly and there’s less chance of root rot from overwatering. But it also means that I have to water these peperomias more frequently, to make sure they the chance get to take up enough water. It can be a difficult balance!
5 | Timing
Perhaps an obvious one, but if the soil is still damp from the last watering, you can water less often. And just because the top is dry, it doesn’t mean the rest of the soil is! Get your hands dirty and stick a finger into the soil – you’ll be surprised how often it’s still damp around the plant’s roots!
The magic houseplant watering formula
So the five factors I take into account when deciding how much and often to water plants are:
- Type of plant
- Light and location
While I aim to ‘do my watering’ each weekend, it’s more of a weekly check in on how the plants doing, including looking at general health and for pests. After taking a look, I might decide that a plant doesn’t need watering for another few days or even another week.
There are, as always exceptions to the rules – some sensitive plants like alocasias and calatheas will throw a grump if left to dry out – but these rules will apply to most regular house plants.
Be aware of how these factors affect each plant, and adjust your watering accordingly.
And no matter how often you water plants, you should aim to thoroughly soak the soil, pour or drain any excess away, and don’t water again until it’s needed. (Resist the temptation to drip tiny amounts in every day!)
As always, trial and error is the best way to learn what your plants needs to flourish.
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