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Various geraniums, planted in window boxes. A watering can stands on a table.

Everything you need to know about watering geraniums

Geraniums are among the hardiest and easiest to care for of all summer flowers. To bloom abundantly and produce lush growth, they need the right amount of water. We explain how best to water geraniums for maximum floral display.

You can tell when many other summer flowers are thirsty. They start to wilt and drop their leaves and shoots. Geraniums don’t do that. Because of their origins in the South African grasslands (known as veld) they are adapted to dry periods and store moisture in their fleshy stems and leaves. They can survive periods of water shortage, but won’t flower well.

On this page you can find the following information:

  • How to tell when your geraniums need water
  • The best time to water your geraniums
  • Tips for efficient watering

How watering combined with fertilising promotes flowering

How to tell when your geraniums need water

  • Push your finger a few cms into the soil. If it feels dry and warm, it’s time to water your geraniums.
  • If the soil is cool and moist, your geraniums don’t need watering yet.
  • If the soil is coming away from the edge of the pot, you’ve missed the best time to water. Geraniums are hardy and can even tolerate extreme drought at times without dying, but you need to remoisten the soil as soon as possible so they will continue to bloom abundantly.

If the soil is firmly in place, the weight of the plant will give you an idea of how much water it needs. You don’t need to water if the planter feels heavy when you lift it. If it seems light, your geraniums need water.

Short-term dryness is less harmful to geraniums than waterlogging!

Check the moisture level of the soil even when it rains. The leaves can grow so densely that little water from above reaches the soil in the container.

Tip: On hot summer days, check both morning and evening to see if your geraniums need water.

How to get dried out soil moist again

Rather than using a watering can, the best way to rehydrate dried out potting compost is to place the pot, box or hanging basket in a tub filled with water for half an hour.

This gives the soil enough time to swell and store water in its pores. Remove the soaked containers from the tub and allow them to drain well. If you were to water with a watering can, the water would simply run off  the dried out soil.

How much water your geraniums need

The rule of thumb for watering all pot and container plants is:

Ten percent of the pot volume per watering. This means watering an 80cm window box with 2.5 litres of water and a geranium pot with half a litre.

You can tell the ideal amount if it soaks the soil, but doesn’t make it sodden. If you find you have to water several times a day using the rule above, use your instincts to increase the amount of water. But beware: Don’t let the soil get waterlogged!

When is the best time to water geraniums?

Morning or evening is best for watering. Less water evaporates before the midday heat so your geraniums can make better use of the moisture. In late evening, skip the watering can, so your geraniums remain dry for the night. Fungal diseases can develop on damp leaves if conditions aren’t ideal.

How to water geraniums

With a watering can (without a spray attachment), water between the plants and below the leaves and let the water flow gently into the soil. Ambient temperature water is best, which is why we recommend watering with a can. If you water with a hose, put the end under the foliage.

Overhead sprinklers or watering with a lawn sprinkler are not suitable. firstly, the drops will damage the flowers, especially on upright geraniums. Secondly, geranium foliage is usually so dense the water cannot reach the roots.

How to make watering easier

Containers with reservoirs make watering easier in two ways. Firstly, they store moisture and release it to the plants as needed.

Secondly, you don’t have to worry about how to water. Simply pour water into the opening on the rim of the container until the indicator shows full.

Water reservoir containers are designed in such a way that excess water drains away, so it’s impossible for waterlogging to occur.

Homemade watering solution using plastic bottles

But containers with water reservoirs aren’t cheap. If you’re on a budget, experiment with empty plastic bottles. For example, poke a few holes in the body of the bottle and bury it in the pot when planting your plants. Leave the top of the bottle above the soil and fill it with water.

Another option is to pierce the cap and stick the bottle upside down into the soil. Due to the laws of physics, the soil will suck the water out of the bottle as it dries. Special watering attachments for plastic bottles that allow you to set the desired drip rate are based on a similar principle.

Combine watering with fertilising

Geraniums are easy to look after. If you water them regularly and remember to fertilise them, these vigorous plants will thank you with abundant flowers.

Traditionally, you mix geranium fertiliser into the water every 1-2 weeks.

Here’s everything you need to know about fertilising geraniums.

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