How to Improve Soil Water Retention

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So, you are absolutely sure that you are watering your plants correctly. The right amount at the right intervals. Yet, they are still showing signs of malnutrition. What is going on here? Well, the problem might be hidden in the soil itself. And no, it’s not the lack of nutrients. It is the lack of microscopic water-retaining pores. You see, it’s not about whether you are watering correctly or not.

The real question here is this: can your soil hold on to the provided moisture? In other words, how to improve water retention in soil in the UK?

Well, let’s see…

What is soil water retention?

All types of soil have the ability to absorb and retain certain amounts of water. The retaining quality is an important factor in gardening, landscaping, and agricultural as plants depend on the moisture in soil to grow and thrive. Certain types of soil are better at retaining water than others due to the size of the particles they are made out of. For example, clay consists of really small particles which means that the spaces between them (called pores) are also very small and therefore better at trapping water compared to sand-based soils which have significantly bigger pores. That is why people who tend green spaces and food-growing land closely monitor the retention of water in order to ensure the health of the soil. Field capacity is the term used to specify the maximum amount of water that soils can keep.

Factors affecting water holding capacity of soil

Before you learn how to improve moisture retention in soil, you need to understand all the factors at play here.

  • Structure – Water retention is greater when the structure of the soil is more porous and aggregated.
  • Texture – Fine texture means there is more surface area, this will improve soil water retention.
  • Soil density – If the soil is too dense, then it cannot hold much water.
  • Climate – Specifically, local temperature is an important factor as the hotter it is, the faster water evaporates from the ground.
  • Soil depth – Simply how deep the soil goes also has an effect on how well it retains moisture and gas.
  • Saltiness – Even if the soil is good at retaining moisture, if it contains too much salt, the plants will have a harder time getting the water they need.

How to increase moisture retention in soil

Method #1. Use peat moss for plants that like acidic soil

Peat moss is a naturally occurring fibrous material. It is obtained from peat bogs where mosses and other plants have been decomposing for long periods of time. Due to its low pH levels, it can be used to grow plants that favour more acidic soils such as camellias or some types of berries.

Method #2. Add wood-based compost to your soil

If you are scratching your head over how to improve soil water retention because your native soil isn’t particularly good at it, then you can mix it with a wood-based compost. The recommended ratio of mixing is about 30-35% of compost to 70-65% of soil. Just make sure to mix them well because you don’t want any pockets of compost alone to form as that won’t benefit your plants at all. Remember, the aim is to increase the available surface area.

Method #3. Use polymer crystals for hanging baskets and pots

You can resort to an entirely artificial product in order to retain the moisture of your soil. Among what to add to soil to retain moisture are the so-called polymer crystals are made from a special material that is able to absorb water. Sometimes they come in the form of granules but essentially they are the same. With time, the material turns into jelly within the soil and it holds on to the available moisture, slowly releasing it to the plants. Once you incorporate the polymer into the soil, it is said that its water retaining abilities will last for about five years.

Simply purchase a bag of these and follow the specific instructions on the packaging. This product is actually a bit pricey so it doesn’t make sense to use it for your entire garden. However, if you are doing something small-scale like a few pots or hanging baskets, then this will do the trick. The best part is that polymer crystals don’t take too much space and are easy to store.

Method #4. Slow down the evaporation with a little mulch

It would be a shame to have the precious moisture evaporate after all the watering efforts you have put into your green space. That is where mulching comes in. This method has been known for centuries. Basically, the idea is to trap the moisture in the soil by covering the top layer with a few centimetres of organic matter. Another benefit you get is that this will prevent the growth of most weeds and over time the soil will obtain additional nutrients from the decomposing matter. Also, you can opt for artificial decorative mulches which can contribute to the beauty of your garden as they come in all sorts of shapes and colours.

Method #5. Get rid of the unnecessary plants

It should come as no surprise that by removing some of the plants, there will be more available water for the growth that actually interests you. This will improve the water-retaining properties of your soil. Naturally, you should get rid of all the weeds as they take away not just moisture but nutrients as well. Once these unwelcome guests are out of the way, consider if there are any other plants that you are not so fond of and could be removed eventually.

Method #6. Maintain the correct soil structure

As mentioned above, the structure of the soil is a critical factor when it comes to its water retaining properties. That is why you need to do a little “digging around” and figure out what type of soil best fits your local climate. But since the focus here is how to increase soil water retention, you probably want to go for a type of soil that has enough pores to hold on to that water. It is safe to say this is the most important factor that you need to ensure. In combination with the methods described above, you will be able to provide the best possible solution for your plants. Another good thing about implementing these strategies is that this will significantly reduce the time you dedicate to watering your growth.

In conclusion, this might seem like another chore added to the endless gardening to-do list. But keep in mind that you need to figure out this only once and then you will know exactly what type of soil is best for each plant you look after.


How is your soil in terms of retaining water? Do you use any special methods, or do you just let it be? Let us know in the comments below.

Posted in Garden Advice

Last update: August 24, 2018

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