Flowered balcony in Rome

Source: Bart van Poll

Flowered balcony in Rome

Watering your patio and balcony plants is important, especially when it has not rained for a few days.

But how do you know exactly how, when and how much water you should give? This article tries to answer this.

Why do you have to water patio and balcony plants?

They are in a relatively small pot. The available water is used up or evaporates fairly quickly.

If you do not water regularly, your plants die.

Which water should you use for patio and balcony plants?

The best water for patio and balcony plants is rainwater or groundwater from a well or drilling.

If you do not have either of those, you can just use tap water.

At what time of the day should you water?

It is best to water early in the morning or in the evening.

This way, the water has time to penetrate the substrate.

If you water during the daytime, when the temperature is highest, a large part of the water will evaporate and be lost. And your plants risk dying of thermal shock: the water you use is much colder than the air temperature.

Source: Own work | CC BY 4.0

Planter with water reservoir

How often do you have to water?

In principle daily but this depends on the precipitation, the type of plants and the wind: when the wind is strong, the substrate dries out.

Some plants can withstand long drought periods, others can survive only a short drought period and yet others must remain moist.

It also depends whether the pot has a water reserve. In most planters for terrace or balcony, a water reserve is built in (see illustration on the right). There are peaks at the bottom of the planter which must be pierced at the top so excess water can drain off.

Automatic watering of plants with a bottle

Source: Own work | CC BY 4.0

Automatic watering of plants with a bottle

How much water should you give?

This also depends largely on the precipitation and the type of plant.

Basically until the water drains out of the bottom of the planter. Note that this only applies when the substrate is moist, if the substrate is dry the water will quickly drain out of the pot if there is no a water reserve.

If you live in an apartment building, be careful not to water your downstairs neighbors as well.

You have to experiment and observe, it is difficult to express in liters or gallons how much water you should give.

Where should you water?

As much as possible on the substrate itself, not on the plant.

For larger plants it is usually easy to pour around the foot of the plant.

For smaller plants that stand close to each other, this is almost impossible. Use a spray nozzle for a softer jet to avoir damaging the plants.

Drip irrigation with bottle

Source: Own work | CC BY 4.0

Drip irrigation with bottle

How do you check if you have given enough, too much or too little water?

There are a few tricks to check if you give enough or too little water:

  • the surface of the soil is still moist 24 hours after watering: you may skip a watering
  • the surface of the soil is dry 24 hours after watering:
    • check if the soil a few inches deep is still moist: if moist, you may skip a watering
    • the soil is dry a few inches deep: water

You could stick your finger in the soil to feel if it’s dry or damp, but a handy trick is a wooden stick in the pot. For this purpose, use a thin, smooth wooden stick such as a support for climbing plants, a wooden skewer or a toothpick.

They are made of porous wood and fairly reliable: if the stick is dry, water; if the stick is damp, skip a watering. So just get the stick out of the pot and put it back in afterwards.

Irrigation systems:

You can also water your patio and balcony plants with a an automatic irrigation system:

  • Automatic watering with a bottle: this allows you to bridge a few days when you are absent or water evenly and as needed.
  • drip system: this allows your plants to water drop per drop. This can be done with a tube or with an insert for PET bottle.