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.

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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…

If you:

  • Are noticing your plants look malnourished;
  • Want to know what factors affect soil water retention;
  • Are trying to increase your soil’s water retention,

Then read on! This article will answer your questions.

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 agriculture as plants depend on the moisture in the soil to grow and thrive. When you water your plants (if you are not sure whether you are doing it correctly, read our blog post on the topic), some of the moisture will become a part of the underground streams or will get drained thanks to gravity. What’s left of the water will get soaked up by the earth, some of the organisms living there and by your flower friends.

If you want to understand how water retention works, we’ll have to go a little in depth about different sorts of soil. 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.

So, which soil has the highest water retention ability?

Like we mentioned earlier, water retention really depends on the soil permeability. For example, clay soil has very small particles that are placed really close to each other, thus making it the earth with the highest water retention ability. On the other hand, a good draining soil is one that mainly consists of sand, however, it won’t maintain the H2O long enough for the plants to soak up their required nutrients.

What do field capacity and wilting point mean?

Field capacity is the term used to specify the maximum amount of water that soils can keep, while a wilting point is the minimum amount of moisture that a plant requires not to wilt. The level of water, present in the soil between its field capacity stage and wilting point and the plants can actually absorb, is referred to as available water.

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

Use peat moss for plants that like acidic soil

Sphagnum 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. If you are dealing with a heavier soil type, you need to be extra careful when adding peat moss. Spreading a bigger amount of the organic product can result in your soil holding up too much water. And you know what too much H2O means, right? Exactly – drowned plants.

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.

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. This gardening product can absorb up 400 times its original weight in 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.

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.

Get rid of weeds and 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.

Plant your flowers in small bunches

Another good way to reduce evaporation is by growing your plant friends close to each other. So if you want to grow flowers, make sure to plant them in small bunches. No matter if you are growing decorative plants or vegetable crops, arranging them in groups will create more shade and protect them from the wind, which will help a lot with the evaporation and moisture retention problem.

Related: How to Get Rid of Coarse Grass in Lawn for Good

Think about your irrigation methods

One of the best ways to increase moisture retention in the soil is to be mindful with your irrigation methods. If you want to ensure that your plants get their required amount of water, it’s best to get an irrigation line. By using this technique you have full control over the whole watering process, while your plants get H2O directly distributed to their stem base. Many people tend to choose overhead irrigation or more popularly known – sprinklers. You see, this irrigation technique works wonders for newly broadcast cover crops, but won’t do you much good in warmer days, because the water will just evaporate. With that being said, no matter how you water your plants, make sure to do it either in the morning or evening. This way you eliminate the chances of evaporation and the soil can absorb the H2O.

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.

Leave your lawn trimmings behind

Instead of throwing away your lawn trimmings, you can leave them on the ground. The cut grass will return moisture to the soil and add some additional nitrogen to your garden. Plus, you get to spare yourself the chore of cleaning up after you’ve mowed your lawn.


  • To understand how water retention works, you need to know the soil type you are dealing with
  • Water retention highly depends on the earth permeability
  • Factors that affect the soils water holding capacity are: structure, texture, climate,
    density, depth, and saltiness

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.

Source: Deposit Photos / By kivitimof 

  • Last update: November 11, 2019

Posted in Garden Advice

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