Water-retaining granules

Water-retaining granules can be added to growing medium to increase its ability to retain water for longer periods of time. They may help reduce the demand of frequent watering during dry spells and are particularly handy in hanging baskets and containers, and where coarse-textured free-draining potting media is used.

Water-retaining granules

Quick facts

Increases up to 400 times in size and weight when wet
Only use recommended amounts
Ensure it is stored as advised
Wash hands after use

Why use water-retaining granules?

Water-retaining granules swell to many times their size when wet and act as a helping hand with watering. Keeping lots of containers and hanging baskets wetted can be very time-consuming but by adding granules to the compost at the time of potting it may reduce the amount of times you would need to water.

However the addition of granules does not replace the need for regular checking of container plants for watering needs, especially when the plants are growing strongly and during dry weather.  

Where to use water-retaining granules

Hanging baskets: The granules should be added to the growing medium as the baskets are being made up, at the manufactures recommended rate. Hanging baskets can be difficult to water, have little growing medium and dry out quickly as they are often high up and exposed to the wind. Adding water-retaining granules may help reduce the effects of water stress and produce a healthy, full basket. However, it is also important to use a fine-textured potting medium as well.

Containers: Pots that are crammed with plants or have fast-growing plants in them such as annual climbers are more likely to benefit from the addition of granules than those containing drought-tolerant or slow-growing plants such as succulents. Add the granules when you are re-potting a container or when you are planting up a new container.

For plants in the ground: Mixing in plenty of organic material such as composted garden waste is more effective than adding water-retaining granules to the soil.

Taking cuttings: Some water-retaining granules can be used neat and swollen with water as a rooting medium for cuttings in the same way that cuttings can be rooted in jars of water.

Cut flowers: Add water to the granules as instructed and then put them in your desired container and add flowers. Food dyes can also be added to give different effects. However, always follow individual product instructions as different quantities of the product are needed for different purposes.

Using and disposing of granules

Points to note when using water-retaining granules:

  • Granules will swell to a considerably bigger size when wet compared to dry so be careful not to exceed the rate of application recommended on the pack when adding them to potting composts. An excess amount will swell and push the plants up and out of their containers
  • Some products have feed added to them and there is now potting compost with the granules already added
  • Ensure the packages are stored cool , dry and out of the sunlight
  • This product is potentially harmful so after handling always wash your hands and keep it out of the reach of children

Disposal of water-retaining granules:

Water-retaining granules do break down over time; one product claims it breaks down within five years. So when your growing media with the granules added is spent, it can be added to your garden compost pile. This can then be used either as mulch or dug into the soil as a soil conditioner.

  • This is only suitable for clean spent growing medium that has no suspected pest or diseases; this should be disposed of at your local refuse centre
  • Also be aware that if you use this as mulch the swollen granules can appear strange (like a clear jelly when wet) sat on top of the soil

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