Rain Gardens: Under-drained or self-contained?

Rain gardens are water management systems which are built to make the most of rainfall which would otherwise go straight down the drain. Water is collected from roofs, lawns and driveways before being channelled into a rain garden where it is filtered and drained away safely. They can be small or large, take up whole gardens or just the borders. To look at, a rain garden is not noticeably different from any other part of the garden apart from that the plants which grow there will be tolerant to moist conditions.

Rain gardens not only look stunning, but they require minimal maintenance and provide ideal homes for butterflies, insects and birds. They also save water and minimise any risks of flooding.

Rain water contains a lot of nutrients and pollutants, so although this water is not suitable for drinking (without being properly filtered first) it is ideal for watering the garden, promoting plant growth and saving you water. Rain water is free, and we get plenty of it here in the UK so we might as well make the most of it!

There are two types of rain gardens, under-drained and self-contained. They should be dug 4-8 inches deep and be filled with a porous planting material.

Under-drained rain gardens are the more complex of the two options because they have a water pipe installed at the bottom to help the water drain away quickly. These are more suitable to areas with a high water table, but are more work to create because they require a filtration zone and a retention zone, usually separated by a layer of pea-gravel or similar material. They also need a liner or filter fabric running underneath.

Self-contained rain gardens have no pipes or plumbing built in and are easier to install because there is no need for any lining or layers of materials. Self-contained rain gardens hold water for a bit longer, but by choosing a porous planting medium drainage is still far quicker than it would be on a driveway! Water run-off from non-porous sections of garden, down pipes and lawns can be directed to the self-contained rain garden, where the plants will take what they need, filter the water and then let it drain away.

The type of rain garden that you choose should depend on how much rain you usually receive, soil conditions, space and budget, but once they are set up they require very little maintenance. When it comes to choosing plants to go in your rain garden, make sure that they thrive in varying levels of wet and damp conditions; they should be hardy and perhaps unsurprisingly, native plants are always a safe option. For the best filtration benefits, plants with deep roots are advantageous, and all plants should be planted when they are young to give them the best chance to adapt to the conditions.

Fancy installing a rain garden but not sure what to choose or where to start? Get in touch with Water While Away!

Rain Gardens

A rain garden uses carefully selected plants and a well thought-out design to make the most of rainfall and runoff. Situated  close to a downpipe or source of a runoff, it slows down the water as it makes its way downhill, which in turn gives the plants more time to absorb the water and reduces concentrations of nutrients in the water.

Building a rain garden allows you to divert rainfall into a bed of plants, which acts as both a natural filter to remove any debris and a super-absorbent sponge to reduce the chances of any flooding. On the surface, a rain garden can look like an attractive bed of plants but in reality these are carefully chosen  plants that are ideal to survive wet, nutrient-rich soil, while acting as a healthy, natural environment. Building a rain garden is not difficult and does not take long,

Typically a rain garden comprises of three parts, or zones. These zones have varying levels of moisture, meaning that plants which thrive in wet conditions should be placed in the innermost circle (or zone 1) of the garden because this zone will be wetter than the two zones around it. The middle ring, or zone 2, should be filled with plants that do not mind standing water as long as it is not all of the time, while zone 3 should include plants that prefer drier conditions.

There are two types of rain garden; under-drained and self-contained, both of which we will be looking at in a blog post to follow.

Surface Irrigation

In this week’s blog post we will be looking at another form of irrigation; surface irrigation. Surface irrigation has been used for thousands of years, and even today is the most common form of irrigation used around the world. Water is distributed over the soil and slowly works its way across the length of a field.

There are four phases to surface irrigation; advance phase, wetting phase, depletion phase and recession phase.

Advance phase refers to the time that the water ‘advances’ over the field and the time it takes to reach the bottom-end. The wetting phase is the time between the advance phase and the water inlet being turned off as it begins to pond. The time that the water begins to drain, and until you can begin to see the soil again is the depletion phase, and the final drainage is the recession phase.

There are there major types of surface irrigation, which are basin irrigation, furrow irrigation and border strip irrigation.

With basin irrigation, the land is surrounded by earth banks in long lines down the length of the area, which forms a basin. The basin is then flooded with water, where it very slowly drains either into a large recess at the end of the land or into another basin that it is connected to. This type of irrigation is the most popular, and is the best way irrigate crops of paddy rice, cereals and wheat. Unfortunately it does lend itself to unwanted water logging, which will result in crops being over watered and eventually causing death. Because of this, it is important to ensure that the right amount of water is distributed over the crops, and that there is a gradual slope so that the water will slowly drain away rather than sit still and eventually become stagnant.

Furrow irrigation uses water channels (also known as furrows) that run parallel to the crops, and again, in the direction of a slope down the length of the land. Water is distributed into the water channels where it slowly flows down the length of the channel and eventually into a drain at the bottom. Crops are grown on banks or ridges between the water channels. This method is particularly suitable for row crops and plants that are fragile to being over-watered. In agriculture, this method is also most suitable for growth of sugar cane, maize and cotton.

The final method, border strip irrigation is a cross-between basin and furrow irrigation; the difference is that the earth banks/bunds (used in basin and border strip irrigation) that run down the length of the land are not designed to flood and create ponds, but instead to direct and encourage the water to flow down to the end of the field. With this type of irrigation, land is divided into bays and strips, which are separated by the earth borders, the channels are longer and narrower, and this type of irrigation is not suitable for small plots of land, but it is ideal for growing pasture and alfafa in large agricultural plots.

However there are problems with surface irrigation, but it is simpler, more affordable and easier to create than drip (which you can read more about in the blog), or other methods of irrigation. One major problem, as mentioned above, is water logging. This can result in completely stopping growth and killing plants. The other problem that many people experience with surface irrigation is salinisation of the soil. This is when the water that is distributed over the land leaves behind deposits of salt (sodium), magnesium and calcium, changing the pH of the soil and eventually reducing its fertility. This can be a huge problem in agriculture, but if you are using irrigation on a smallish scale either in a garden or an allotment the problem should be avoidable providing you don’t use salt-rich irrigation water. Have a look at our website for more information about irrigation and micro irrigation, and please contact us if you have any queries.

Drip Irrigation

Providing your garden with the right amount of water can be a challenge, especially if you have a range of plants that require different amounts. Drip irrigation is a very efficient way to water your garden, it uses up to 50% less water than other irrigation methods (such as sprinkling) and saves you the time and effort of having to do it yourself.

A drip irrigation system allows water to slowly drip onto the base of the plant; either onto the surface soil or directly onto the roots. This means that only the soil immediately around the plant is watered, rather than larger areas and thus saving water. This also means that weeds are discouraged from growing because the soil between plants is much drier and is an unsuitable environment for unwanted nasties. This method of irrigation is suitable for fruit, vegetables and most other crops in your garden.

There are other major advantages of drip irrigation, such as that minimal fertiliser and nutrients are wasted, irregular shaped gardens can be easily accommodated to and that lower-quality water can be used. Recycled water or collected rain water is suitable for drip irrigation, but it is important to ensure that there is no sediment within the water as the pipes have very small holes which can easily become blocked. Because of this, many drip irrigation systems have a filter built in to prevent blockages.

Drip irrigation systems can be large or small, and can be very complicated when used in agriculture. A network of pipes, tubes and valves transport the water from the source directly to the base of the plant. Plants that are watered in this way are known to be strong and healthy because they are subjected to the correct amount of water at the right times, and since the foliage does not get wet it also avoids many foliage diseases.

Preparing Your Garden For Spring

If you’re a keen gardener, this time of year is very important. It’s the time to start preparing your garden for spring and new growth; preparing the soil to provide optimum conditions and creating space for new flowers, bushes, fruit and vegetables to flourish.

If you haven’t already, the first thing you can do to prepare yourself and your garden for spring is basic maintenance such as removing any dead plants or flower heads, raking the lawn to collect leaves, dead material and debris, cleaning out greenhouses to make space for your seedlings that will be growing in a few weeks and cleaning any garden tools. Making sure that your tools are free of bacteria and fungus from last year which could be introduced to your new plants, and keeping tools sharp will improve the quality of pruning or any cuttings that you are taking. If your garden is particularly wildlife friendly, it is best to leave the clearing up of flower beds and borders until spring time to maintain habitats.

Over the rainy season things in your garden can become damaged and in be in need of repair. This is the perfect time to fix any fences, trellises and raised beds. Although it might still rain a fair amount, getting these little jobs done now will give you more time to spend tending to your garden throughout the spring and summer. On a dry day it is a good idea to treat any wooden structures with a wood preservative.

Once the frosty season is over and soil is workable again, you can begin to plant bulbs and early spring vegetables such as leeks and lettuce – this time of year is perfect for planting daffodils and other bulbs to have a colourful garden in a few months.

Installing a water butt or other method of collecting rainwater is another thing that can be done while you are clearing up your garden, make some space and position the water butt beneath the down pipe to collect run off from the roof. If you’re on a water meter this will quickly save you money, and many plants actually prefer rain water because tap water can often be slightly alkaline.

With spring not far away, with it comes brighter days, warmer temperatures and hopefully a lot less rain. Preparing your garden now will encourage better growth throughout the year and give you more time to enjoy being outside with nature. If you are re-organising your garden now could be the time to consider underground tanks, irrigation systems and water management systems; if so, don’t hesitate to get in touch with us to see what would be the best option to suit your requirements.