Raining Gardens: A Decoratively Powerful Approach to Conservation

For both wildlife and vegetation the privilege of being able to access water is one of the foremost struggles that follows them their entire lives. In Conservation practices, it is seen that a healthy ecosystem/habitat will generally support wildlife, but the type of habitat depends on the availability of water. For example;

1. An abundance of water = Ponds, Rivers, Oceans.
2. A large amount of water = Swamp, Marshlands, Bogs & Fens.
3. The presence of water monthly = Forests, Grasslands, Heathlands etc
4. Little-to-no water: Deserts, Savannah, and perhaps counter-intuitively, annually frozen regions.

So, you can have a vague understanding of how water has a role in shaping the local environment. Yet this is a simplified view, not taking into account soil water-retention, sunlight intensity, local & global climate patterns, local vegetation type, and so on and so forth. It’s tricky, but manageable for small sites!

Here’s a thought provoker: if you’re trying to promote wildlife & plantlife, how do you control the available water supplies in a habitats that span acres, miles, or even countries?

Well, as we in the UK have lost 90% of our wetland habitats in the last 100 years, our conservationists have gotten creative! Methods such as Natural Flood Management, Vegetation-Inducing Water Quality Improvement, Natural Rainwater Catchment, as well as Re-Introducing species to revert habitats are the heavyweights of this topic.

It’s great to know this, but how does this help you? Well your garden, for one, is a habitat that needs water right? But where does it get it from, do you water it occasionally or do you prefer to water for the rain to come? Either of these are valid options but both have the same flaw. How does wildlife gain access to water, as these water sources don’t stay around for long. Sure, maybe theres a nearby pond a half-mile away, but how will wildlife that cannot cross fencing, roads, or human territory reach them? Well, if you’re keen to do something about that to help support local wildlife that provides a drinkable water source yet doesn’t need you to skim off algae, feed fish, or refill, then Rain Gardens are an amazing garden-level equivalent to the conservation management techniques I just mentioned.

Rain Gardens are a style of gardening introduced to combat low water resources, heatwaves, reduced water tables, and negative impacts rainwater run-off. If you have any water-proof surfaces near your garden, as well as the right soil, you’re ready to go!

What is a Rain Garden?

The end goal of all Rain Gardens is to create a system of whereby rainwater runs off man-made structures, such as rooftops, using self-made water-highways to deliver it to a certain portion of the garden. This part of the garden will be re-designed to allow it to become temporary bodies of water as it is not a water garden. Nor is it a pond or wetland. In fact, a rain garden is dry most of the time, only retaining water during and following a rainfall. Because of this feature, rain gardens will drain within 12-48 hours

The overall aesthetic of your garden does not actually differ drastically, as you’ll see in the upcoming ‘How-to’. Depending on your choices, a ‘dimple’ of your own choosing will be created in your grassy patch, and it simply fills up with all the rainwater that is redirected it’s way. You will have the choice to introduce new plants that enjoy being semi-submerged sometimes, whilst your local groundwater will be refilled, your nearby vegetation healthier, the local wildlife will be visiting more often, and the many other benefits mentioned later on in this post.

That’s it, your own ephemeral wet grassland, a valuable hotspot of quality habitat!

This is a project suitable for anyone with a well-draining soils and a relatively flat piece of land. A moderately challenging project for the autumn or spring, depending on how you want to spin it. This is a water feature that projects a soul-filled atmosphere, as well as a feeling of depth to an otherwise static green-scape.

Garden Requirements:

• A patch in full sun or partial sun
• In a well-drained area, on a very gentle incline (10% or less)
• Ideally siting the ‘rain garden’ portion further than 5m from any building foundations. If closer, seek advise to avoid any damage to foundations via infiltrating waters.
• Where it is practical to install a route leading to the main drainage system below the rain garden in case of excessively heavy storms.

How-To:

I will describe how to create a standard rain garden, the choices of what to use as water-highways, accompanying plants, and other personal decorative decisions will be all yours!

1. Pick a suitably flat (or up to a 10% incline), and if applicable, a low-lying area on your lawn.
2. Ideally, choose a spot of full-or-partial sun! As well as 5m+ from any house foundations.
3. Check Here to see if your garden soil is the right type. Ideally as you check, the water drains away at half an inch per hour, however the rain garden will still work if the draining rate is up to 2 inches per hour. If it is any quicker or slower, the sight is unsuitable.
4. You will be digging down slightly, so depending on how far you want to go, measure an outline of the size & shape you’ll be going for.
5. Width: create an area that constitutes at least 20% of the area of the roof that you will be redirecting the rainwater runoff from. You can judge by eye, but if you’re math’s inclined you can figure out the area [length x width = area], and then find 20% of that number [area x 0.2 = 20% of area][(area / 100) x 20 = 20%].
6. Depth: depends on how fast your soil drains. At minimum, dig 15cm deep, this is for soils that drain at 5cm per hour. Dig deeper by 3cm for every 1cm slower the water drains per hour. Don’t forget to slope off the edges of your hole! this allows for some edging around the pool, and to make sure no wildlife cannot get out.
7. The final product should have created a basin shape: compensate any sloping by digging deeper in the higher end to create a level basin floor. This is now an area that will accommodate UK summer rainfalls.
8. Use the removed soil to create a Berm (raised ‘lip’ around the edge), compact it, and raise it up to 30cm high & 10cm wide. If you have the preference to do so, leave a notch in the berm and layer it with gravel. This can be used to direct excess overflow in the direction of drains or another portion of the garden, such as a pond.
9. Water Highway: where practical for you, run your water transport system from the nearby roofing you have chosen so that it carries the run-off water into the basin as & when it rains.
10. At the point of entry, feel free to add gravel or cobble to prevent soil from washing away.

Extras:

With a few adjustments to the depth & width of your dug up rain garden, you can affect how long the rainwater stays before draining. It’s about your preference!

The best time to be doing this is in early Spring or early Autumn, as the soil will be dry enough but not compacted. Similarly, depending on your choice of plants, these are the best time to establish them in the soils.

You can tie in other features into your garden, such as rain-fed ponds, rainwater-planters, or water butts!

Types of Plants

Planting plants that thrive in these new conditions is governed by your choice, as well as how well your rain garden receives/drains rainfall. Here are some options:

For the base of the basin:

1. Yellow Iris: Iris pseudocorus
2. Soft Rush: Juncus effusus
3. Sedge: Carex pendula
4. Cardinal Flower: Lobelia cardinalis
5. Arum Lily: Zantedeschia aethiopica

For the edges:

[Grasses]

1. Feather Reed Grass: Calamagrostis brachytricha
2. Tufted Hair Grass: Deschampsia cespitosa
3. Silver Grass: Miscanthus sinensis 

[Shrub Species]

1. Elder: Sambucus nigra
2. Dogwood: Cornus sanguinea
3. Smooth Hydrangea: Hydrangea ‘Annabelle’
4. Beach Rose: Rosa rugosa

[Herbaceous Perennials]

1. Bugleherb: Ajuga reptans
2. Bellflower: Campanula glomerata
3. Montbretia: Crocosmia ‘Lucifer’
4. Cranesbill: Geranium ‘Rozanne’
5. Daylillies: Hemerocallis
6. Siberian Iris: Iris sibirica

How a Rain Garden Benefits Wildlife:

From downpour to drizzle, you’ll find rain water runs of waterproof surfaces (rooftops, driveways, patios etc) and drains away wherever it naturally can, like to our man-made drains, and similarly also to any patch of soil, grass or natural landscape. Whilst this shouldn’t be any issue, this run-off rainwater is unlike the rain that falls straight from the sky to the soils/plants, water running off these waterproof sections collect pollution along the way in the form of chemicals, bacteria, fertilisers, or even ‘settled’ car emissions & oils. This pollutant laden water will enter our streams & ponds untreated and impact the wildlife there, and this is estimated to account for 70% of all water pollution.

Fortunately one way to combat this is through Rain Gardens, as they collect, filter and treat this rainwater runoff. Afterwards, as the clean water drains into the soil it seeps down to recharge groundwater aquifers. This is style of gardening filters out pollutants!

But that’s not why the Rain Garden is advocated as a sanctuary to wildlife, it’s because it also has other features:

The improved water quality provides local stormwater, attracting beneficial birds, butterflies, and insects to stop by temporarily to drink & rest as they provide their ecosystem services to the local habitats. Due to the presence of temporary water sources, and more resilient wildlife services, a preservation affect is encouraged for the scarcer native vegetation you will have introduced, as well as those that get introduced by wildlife. This will happen as high-quality temporary water sources are nationally rare due to human activity, and the naturally harsh conditions on dependant vegetation for this type of habitat increase, making the native vegetation rarer. Wildlife will be able to access their native vegetation through your garden now, and bring alongside them seeds, nutrients, and behaviours that encourage your Rain Garden to thrive.

On another note, it’s ability to soak up, store, and drain surplus water helps it prevent local water-logging & flooding from rain to deter damages in your garden, allowing other vegetation to survive healthily. As rain gardens strip up to 90% of chemicals & harsh nutrient levels, and 80% of sediments from run-off rainwater, it’s vegetation is incredibly sturdy, healthy and resilient to damage meaning it can service a massive amount of wildlife. It’s also this ability of water & nutrient storage that allows it’s vegetation to survive long droughts, whilst feeding & satiating thirst of any local habitats and inhabitants. Food? We have it. Water? Got it. Housing market? Plenty. Oh, and the aesthetics are appreciated from bugs to humans, what do you think catches their eye to draw them in?

On a final note, this is a bit of a curve-ball but you’ll be appreciative to have heard it. Reduced erosion is also a benefit. A strange term to hear in this concept, but it’s true. A very brief summary would go; (1) rainfall & runoff removes topsoil layer, (2) rain-garden attracts rainwater runoff, (3) rain-garden redistributes soils back into local garden through ‘nutrient cycle’, (4) stored water & nutrients strengthens vegetation root systems, binding soils to protect against erosion. Ta~da, everyone wins.

Sorry, last final note… promise! You’ll really like this one! Because Rain-Gardens are technically ‘dry’ a proportionate amount of the time (drain after 12-48hrs), they aren’t ponds, wetlands, nor water gardens… they prevent the breeding of mosquitos! Told you you’d like it. This isn’t technically a ‘wildlife benefit’ however as mosquitos do not breed nor inhabit these types of environments, it is not a loss either. I wanted to ensure there was one less reservation against building a rain garden. Now, I hope you enjoy moving on to the rest of the read!

How a rain Garden Benefits You:

Well for one, this is one of the few ways you can design your own water features! This is about redirecting water towards a particular feature of your garden, but there’s no concrete method on how that water gets there. Perhaps a particularly complex yet aesthetically pleasing system of water-highways, rills or channels! Consider linking elements like connecting waterfalls, or maybe a rain-chain, water-butt, stormwater-planter, or pond? Heck, you could even just drill holes in random objects and let water pour out of them! It’s a good time to get creative on your drainage system and add your own flair.

One great positive regardless of your drainage design is the fact that Rain-Gardens are an ‘Add-on’ to your garden, but after that they are low-maintenance, they won’t be needing regular care unless you notice a blockage or leak. Heck, even the plants you plant for your rain garden won’t need much watering or fertilising, that comes with the rain!

If you’re clever about things, you can consider the entirety of your garden as an extension of your rain garden. If your garden struggles with flooding or slow-draining soils, clever placement of the rain-garden portion can help your garden absorb up to 30% more than it’s usual capability. If you’re interested in doing so, you’ll be able to plant a greater range of perennials & other native vegetation, as you’ve now created new niches in your garden (occasionally water-inundated, varying humidity levels, water accessible soils, nutrient gradients etc). Find out what array of plants work well for you and your personal design!

Well whatever you do, if done right, will have a net-positive affect on wildlife. Your garden will become a bustling central of insects & birds, you’ll be able to connect with nature in your back garden and show it off to any interested persons. The improvement of biological factors, water-quality especially, is a bound to benefit the resilience of local plant-life! If you have fruiting trees & shrubs, you’ll find the following years you see greater yields of fruit, another great time to try your hand at crafting wines, jams or other such things!

But to summarise, rain-gardens are beneficial in many senses of human-benefit. The improved water-quality has knock-on results on your plants, the provided localised flood control ensures you soils aren’t easily damaged & plants aren’t waterlogged, whilst replenishing local groundwater supplies for future droughts. Diverse planting opportunities for wildflowers, shrubs, sedges, ferns, rushes and small trees become more readily available as well! The unique aesthetic landscape can be personalised, and tie buildings closer to the surrounding environment to enrich it rather than degrade, providing you with bountiful wildlife alongside greater flowering displays, increased edible products and a cleaner environment for health.

Truly, this is a method of gardening that affects many aspects of life, and not just our own.