Create a container pond
by Rhiannon James
A pond is a great addition to the garden, but building one can involve some serious hard labour. So, if you’re short on time or space, ditch the digging and create a quick and easy container pond.
The finished result will add a different dimension to any small space, bringing the cool, calming presence of still water to the garden, attracting lots of wildlife and giving you the chance to grow a whole new range of interesting aquatic plants.
This garden feature is great fun to plan, quick and easy to make and, if you add the right plants, will stay clear and fresh with minimal amounts of care.
Stuff to get
1. A Container
2. Individual aquatic baskets/containers and aquatic compost (if needed)
6. Extract of barley straw solution (optional)
1. A container
You can use any container that will hold water to create a pond, or you can buy a commercial one from a garden centre or specialist nursery. We chose an 80cm diameter container with a glossy copper finish from Waterside Nursery (www.watersidenursery.co.uk).
If the container is being recycled or reused, you will need to clean it thoroughly. It’s also essential that the container is watertight as drying out is fatal to water plants. Cover any drainage holes or gaps in the container with a piece of pond liner sealed at the edges with waterproof glue or silicone-based sealer. Terracotta is not the best choice for a pond because it’s porous. To use this type of container you will need to paint the inside with several coats of a sealant such as yacht varnish.
2. Aquatic baskets / containers and compost
Plastic mesh baskets hold soil around plants’ roots, whilst also allowing a free flow of water and oxygen. They can also help to stop faster-growing plants taking over the container. Plants are often ready-supplied in these baskets, but if not, or if some of your plants need repotting, you’ll need to buy some. Bear in mind that not all oxygenators and floating plants need to be planted in soil – check with the nursery or garden centre when you buy your plants.
A medium to heavy loam garden soil can be used as the growing medium for aquatic plants as long as it’s free from fertilisers and herbicides. Otherwise, it’s best to use aquatic compost.
You’ll probably need to create some form of shelving in your container, to raise some of your plants to the right level in the water. Clean bricks (which are free of lime) will do the job or for a few pounds you can purchase a plant support ring which fits a circular container.
Rainwater is the best option for your container, but if you don’t have enough to hand, tap water will also work.
Planting a container follows very similar principles to planting a full-sized pond, just on a smaller scale. There are four main groups of plants to pick from:
Waterlilies and other deeper water aquatics: There are beautiful dwarf and miniature waterlilies available, which are suitable for a container pond. We’ve used Nymphaea ‘Aurora’, which has flowers which open yellow and deepen to an orangey red, but you could also try ‘Pygmaea Rubra’ (red/pink flowers) or ‘Pygmaea Helvola’ (white and yellow flowers). The crowns of these plants need to be around 15 to 25cm deep in water while their leaves will float on the surface. As well as being a gorgeous feature in their own right, waterlilies will help to shade the water in your container, which will deter algae.
Floating plants: These plants, which float on the surface of the water, also help to create shade and to stabilise the water temperature, whilst adding another layer of interest to the planting. Try the white-flowered Hydrocharis morsus-ranae (Frogbit).
Marginal plants: These plants, which grow in shallower water, are great for adding a range of interesting architectural shapes, textures and flowers to your container pond. Just make sure you choose plants which are in proportion to the size of your container.
We’ve used: Caltha palustris ‘Flore Pleno’ (Double marsh marigold) which has bright yellow flowers in spring and sometimes again in late summer; Iris fulva which has blooms in a lovely shade of terracotta; Primula florindae which has fragrant yellow flowers from July to September; Sagittaria graminea ‘Crushed Ice’ which has small white flowers and variegated foliage; Carex acuta ‘Variegata’ – a grass with white and green striped foliage; Schoenoplectus lacustris subsp. tabernaemontani ‘Zebrinus’ which has stems barred white and green and a miniature bulrush, Typha minima. All these plants need between 5 and 10cm of water over their soil, apart from the Primula which needs shallower water.
Oxygenating plants: These plants sit below the water surface, adding essential oxygen to the pond and helping to keep it clear of algae by competing for nutrients and light. We’ve used Ceratophyllum demersum (Hornwort) which has dark green, feather-like foliage.
Look for a selection of plants that will provide interest throughout the spring, summer and autumn and go for a mix of upright plants, which will give height to the container, plants that will grow across the water’s surface and at least one oxygenator. Try to pick varieties that are small and slow growing so no one plant takes over. If you’re feeling stumped by all the choice, some nurseries offer their own selections, tailored to the size of your container, which will give you a good balance of shapes, sizes, textures and flowering times.
When to do it
Mid-spring to early summer is the best time to plant up your container, as the water will be fairly warm and plants should establish well.
Step by step
The first thing to do is to work out the best location for your container.
A bright position, with sun for about half the day, is ideal, as this will provide the best conditions for your plants without encouraging too much algae. If your garden is shady though, don’t despair, there are still interesting and attractive aquatic plants that will thrive in these conditions.
It’s best to pick a spot away from trees, so you can keep your container clear of dead leaves and other litter.
It’s also worth thinking about the backdrop you’d like for your container. You could make use of existing plantings or pots, or you could plant up some specimen aquatic plants in separate containers to set off and harmonise with your container pond.
Finally, if you have small children, you’ll need to make absolutely sure they can’t fall into the container, however small or shallow it may be.
Put in the shelving frame or blocks/bricks, making sure that you will have the appropriate level of water coverage above the plants you have chosen. Our waterlily, for example, will be sitting on a small block on the base of the container, while our marginal plants will be placed in the frame.
Place your container in its final position. Once it’s full of water, it’ll probably be too heavy to move.
If you need to plant up or repot any plants, you’ll need to do this now. If your aquatic baskets have very fine mesh, you can plant straight into them. If not, it’s best to line your baskets with a thin porous material such as horticultural fleece or hessian to prevent soil washing out into the water. Part-fill the basket with aquatic compost so the plant will be sitting at the same depth as it was in its original container. Then take the plant, spread out its roots and put it into the basket, back-filling carefully with more compost. Firm plants in securely, water well and put a thin layer of gravel over the surface to stop compost washing away when the water is added.
Place your plants on the base of the container, in the frame or on bricks, at their preferred depths in the water. To get our waterlily at the right depth, for example, we’ve cut a hole in our frame and placed the pot on a small shelf placed on the base of the container. Meanwhile, we’ve raised the primula slightly higher than the level of the frame, using a clean pot saucer. You can then play around with the arrangement of the plants until you find the one that works best. Just remember not to add the oxygenating plants until the container has been filled with water.
Once your plants are in place, you can add the water. The easiest option is to use a hosepipe but try to add the water gently, with minimal disturbance to the plants and the compost. When your container is full, check each plant is still in the right position and none have toppled over. You can then add in the oxygenating plants.
Add the recommended amount of extract of barley straw solution to help to keep the water clear of algae.
Caring for your container
Maintenance is simple and not at all demanding:
It’s important to keep water levels topped up, especially in the summer (try to use rainwater if you can). It also helps to check the condition of your water regularly. If it turns green due to algae growth then add some extract of barley straw and this will clear it. Try to keep the container clear of dead leaves and other decaying foliage.
Refresh the container once a year with new water in spring or autumn.
In early spring and autumn, check the condition of your plants, cutting back anything that is getting a little bigger than you want.
After the first year, your plants will also benefit from an annual feed in spring. It’s best to use specialist aquatic fertiliser tabs which are pushed into the compost so the food does not escape into the water.
Protect your container from severe frost. You can let the surface of the water freeze over, as long as you keep an air hole open, but don’t allow the whole container to freeze solid. If you can, move your container to a sheltered spot, but if it’s too large to pick up, you can wrap it in fleece or bubble wrap. Also, before the severe cold affects the container, it’s best to reduce the water level slightly, which will help to ensure the container is not damaged when ice forms.
Although it may be tempting to add fish, it is best not to, as they can damage plants.
Growing individual plants in small containers
Some plants, such as irises and miniature waterlilies, can look spectacular when they are grown in their own individual containers. Using separate containers also allows you to grow some striking, architectural plants that are too invasive for a mixed container pond, such as horsetails. Grouping different sizes, shapes and colours of pots can make a beautiful garden feature.