Watering plants: when, how often & what kind of water?

Watering plants is a basic and vital part of plant care. Although watering is fundamentally important, there is hardly a blanket rule that applies to them all.

Plants need water to maintain their vital functions. But how do you water plants correctly? There are many factors that influence how often and how much a plant needs watering, including pot size, temperature, soil type and sunlight. Read on to find out all you need to know about watering plants.

Why do you need to water your plants?

It is not just animals and humans that depend on water. Plants also consist of living cells filled with liquid, and they need to regularly replenish their water supply. Plant cells are largely made up of water, and if a plant does not get enough water, i.e. low water pressure in its cells, it will not be able to maintain its upright form. Consequently, it develops limp leaves and begins to wilt. The water within the plant also serves to transport nutrients. Most plants absorb water through their roots. That said, there are exceptions, such as tillandsias, which absorb moisture through their leaves.

How often should you water plants?

There is no one-size-fits-all answer to the question of how often you should water plants. As mentioned above, how often you need to be watering your plants depends on many factors.

One such factor is the weather. If it is raining cats and dogs, additional watering in the garden is not necessary. If there are long periods of drought, on the other hand, you may need to give your plants a drink.

The time of year also plays a decisive role. Watering plants is hardly necessary in winter, because most plants are not actively growing during this time due to a lack of light. This means that they absorb almost no nutrients and also lose less water due to the lower temperatures.

The soil type, the location and of course the respective plant species also affect the water requirement.

How does the soil type influence how often you have to water?

• Loess soil and humus-rich or clayey soils store the most water, keeping it readily available for plants.
• Loamy soils also store a lot of water, but this is mostly retained in the soils’ pores and only available to plants to a limited extent. They need to be watered more frequently than humus-rich, loose soils.
• Sandy soils have very coarse pores through which the water simply runs off into the subsoil. They dry out quickly and need to be watered at shorter intervals.

How does the location influence how often you have to water?

• More evaporation takes place in sun-exposed locations than in shady ones
• A mulch layer can reduce water evaporation from the soil by keeping it cool and covered
• In windy locations, more water is lost through evapotranspiration, because the air movement quickly removes moisture

How does the type of plant influence how often you need to water?

• Nurseries and specialists categorise perennials according to their habitats and moisture preferences. This makes it easier to find out how much moisture certain plants need.
• Nurseries can provide expert advice on the moisture requirements and suitable locations for plants.
• Succulents store water well and can cope with less watering.
• Plants with little leaf mass or small, hard leaves have a smaller evaporation surface. A thick wax layer on the leaves also reduces transpiration.

Tip: it is also important to know whether the plant grows in a pot or in the ground. The pot size and the type of container influence the watering intervals. Glazed and plastic are better for preventing water from evaporating. If the plant is in a spacious pot, it will need to be watered less often.

Summary: how often should you water flowers and co. in the garden?

• There is no one rule − the watering interval is influenced by many factors
• Watering intervals depend on weather, soil type, plant type, location, etc.
• Signs of drought include: crumbly, cracked ground and wilted plants
• Plants in sandy and clayey soils need more frequent watering than ones in humus-rich or clay soils
• Follow the information on moisture requirements provided by nurseries
• Plants with fleshy, hard or hairy leaves and a small surface area tolerate drought better

When should plants be watered?

The best time of day to water your garden is early in the morning. The temperature is cooler at this time of day, so water evaporates less. Of course, the time of watering also depends on the weather. Watering is especially important when there is insufficient rainfall. In winter, only water your plants during prolonged drought and only during frost-free periods, otherwise you may harm your plants.

Should you water when it is hot outside? It makes no sense to water in the blazing midday heat, as much of the water will evaporate before it can seep deep down to the roots. However, in midsummer, plants do rely on receiving extra water. It is best to water your plants early in the morning or in the evening after the midday heat has subsided.

How to water plants properly

You might think there is not much you can do wrong when watering plants, but here are a few tips to help you give your plants the best possible care.

Tips for watering garden plants

• After the initial planting, watering intervals should become fewer and further between. This will condition the plant to form a strong root system which reaches for water reserves deep in the soil. This is especially advantageous during periods of drought.
• Mulch reduces the evaporation of water from the soil. It not only keeps your soil evenly moist, but it also suppresses weeds and can create a visually beautiful, natural bed surface.

• The water should be distributed evenly along the rootstock of the plant. Therefore, bottom watering plants is the best option. Watering from above − i.e. watering the leaves − can promote fungal diseases on the leaves, and the water is not absorbed by the plants but rather evaporates unused.
• To save on water and work, practice watering your plants infrequently but thoroughly rather than giving small amounts of water frequently.
• Ollas and drip hoses can be used in the bed for a constant water supply.
• Avoid sprinklers as the fine water droplets evaporate quickly in warm weather, so water loss is very high on these days – up to 50%.
• A watering trough around plants contains the water to the area around the plant and prevents runoff.

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Tips for watering potted plants

• Potted plants have considerably less substrate available and, therefore, have less space for root growth. As a result, they need to be watered more often.
• Heavily dried out soil absorbs water very poorly at first, so it needs to be watered several times or placed directly in a container of water for a few minutes so that the soil can slowly soak up the water.
• Using a finger to check the soil is a good way to determine whether it is time to water your potted plants. Simply check with your finger to what depth the root ball is already dry. With smaller plants, the weight of the planter can indicate the amount water saturation. If the planter feels unusually light, it is time to water your plant again.
• Potted plants are usually potted in soil containing peat. This can store a lot of water and avert frequent watering. Unfortunately, once the peat has dried out completely, it becomes water-repellent and difficult to moisten again. For this reason, as well as from a sustainable perspective, peat is increasingly being excluded from gardening products. Some biological alternatives are soils made of wood and coconut fibres. Whilst these alternatives do not store water as well as peat, they also do not become water repellent when they dry out. Plus, they have a better CO₂ balance. This also applies to our Plantura organic composts, which are peat-reduced or peat-free and sustainably produced. In many cases, our Plantura Organic Flower Compost is ideal for the balcony.
• It is important to note that waterlogging is a common problem for potted plants. If water accumulates at the bottom of the pot, the roots will start to rot over time. Regularly check whether there is water in the saucers under your potted plants.

Automatically watering plants

It can be a lot of work to regularly take care of your plants’ water needs. Do not worry. There are solutions.

Drip systems or sprinkler systems can be controlled very practically with a pump and timer. The pump automatically delivers water to the plants at the desired time. For flower beds, the use of drip hoses makes the most sense. There are even watering computers that you can programme with different watering cycles for different zones in your garden.

You can buy the individual components or even complete watering sets from specialist companies or DIY stores and garden centres. Irrigation computers can cost between £50 and £200. Watering clocks, on the other hand, are available for as little as £30.

Tip: to help you care for your plants while you are on holiday, we have put together some tips for watering plants while away in our article. Ollas and watering spikes are also methods for providing potted plants with constant moisture over a period of days.

Do plants need tap water or distilled water?

The type of water influences the substrate properties and thus the living conditions of the plant growing in it. The lime and salt content play an important role here. Depending on where you live, your tap water can be hard or soft. Hard water contains some lime, which could cause problems after a while, especially for sensitive plants. In contrast, the lime and salt content of rainwater is low, so you can use it for watering plants without a second thought.

Watering plants with distilled water is not a good idea. Distilled water no longer contains any salts, which disturbs the plants’ osmotic absorption of the water. Sparkling water, on the other hand, can also be used for watering plants, as its salt content is usually not too high or low.

Now that you are well-acquainted with the watering of outdoor plants, you can read about how to water indoor plants in our linked article.