21st Nov 2019
In this, the 2nd of our series of Bradshaw's Guides we tell you how to add plants to your pond and why it's such a good idea to do so.
How to Build a Pond Part 2 - Adding Plants
So you’ve put in your pond liner, filled it up and done your edging. Now you might want to add some plants. These make the pond look more natural and are a great habitat for all kinds of beneficial bugs - not to mention frogs and newts. The more plants you have the less problems you’ll have with green water and blanket weed (the long strands that look like green hair).
All plants should be in a basket, most come in one from the garden centre or friendly online retailer. Check that the roots are not poking out of the pot, if they are you might need to repot it into something bigger, if they're not you can put it straight into the pond.
If the plant is dry you should soak it in a bucket first, otherwise soil will muddy the water as you put it into the pond.
If you need to repot use an aquatic basket, you can use a hessian liner inside the pot to stop the compost from coming out. You must use aquatic compost, it is heavier than the normal stuff so it doesn’t float and it doesn’t have nitrate based fertilisers in it. Nitrates can make your pond go green overnight!
It’s worth adding a fertiliser tablet to the pot, especially with lilies. Some gravel on the top makes it look good and keeps the soil in place.
This is down to what kind of pond you want. If it’s all about the fish then you might not want too many plants but if your pond is for wildlife, bugs and frogs then you’ll need a lot.
Pond plants grow quick! Start with a few that you like and see what happens, you can always add more later. Think about where you’ll stand or sit to look at the pond. Near your feet you only want low or submerged plants, while at the back of the pond you might want something taller to frame the view and disguise the fence that’s behind it.
If you have shelves in your pond you’ll have more choices but if not you can always add floating islands or planters that hang over the edge, or even a submerged brick stack with a small flagstone on it. It can be useful to buy an extra planting basket, turn it upside down and wire it to the basket of your new plant to raise it up a bit. Aiming to cover about ½ the pond surface will help with the water balance and reduce green water problems.
It's deep man!
Pond plants can be split up into different groups based on how deep they like their water. Check the pot labels in the garden centre, they’ll have a depth guide on the back so you know where to put them.
Moisture Loving plants, sometimes called Bog Plants are those that like the soil to be damp around their roots. The stem and leaves of the plant should be out of the water for them to flourish. There are lots of great varieties like Lobelia cardinalis (tall and with deep red flowers), Gunnera manicata (giant rhubarb like plant), Arum Lily (Zantedeschia aethiopica, green stems and shiny leaves with a white tube like flower).
Marginals are those plants that can be a little underwater and the stems and leaves grow up and out. We like the Iris family, Yellow Flag Iris (Iris pseuadacorus) is the most common but there are lots more. Some other plants can spread to cover the water surface like water cress, which is tasty in a salad - or water mint (Mentha aquatica) which smells good.
Submerged plants or oxygenators are plants that grow entirely under the water. Elodea crispa or goldfish weed is the most common and is usually bought in weighted bunches that are just thrown into the pond. Some other varieties look prettier and grow a bit more slowly like Parrot’s Feather (Myriophillum brasiliensis) - they are usually potted. These plants do add oxygen to the pond in the day but take it back at night so don’t rely on them for your fishes health, you can always add an air pump instead.
Floating Plants simply float on the surface and look great while adding a bit of shade and cover for your fish, from predators like birds and cats. Usually sold in a pot of water you just throw them on the pond surface and leave them to it. Water Hyacinth (Eichornia crassipes) is the most common and can flower if the summer is hot, they are not frost hardy though so will die off in the winter.
Lilies are the classic pond plant and nearly everyone wants at least one. There are varieties suitable for depths of between 6” and 4’ (15 to 120cm) but most live in the deepest bit of your pond with water between 2’ and 4’ deep (60 to 120cm).
When you first add a lily it will usually have short leaf stems so if you put it straight to the bottom of the pond the leaves won’t reach the surface. You need to lower it gradually. Start with it on a shelf so that the leaves are close to the surface and they’ll stretch up to the top in a few days. Once they are spread out on the surface lower the basket a little further, say 6” (15cm) and wait for the leaves to spread out on the surface again. Keep doing this until it is on the bottom of the pond.
You could use a stack of bricks to help with this process, just take off one layer at a time.
Some people want to only add native British plants to their pond, if that’s you then look for the Union Jack on the label when you buy. There are some foreign species of plants that are considered a pest and shouldn’t be sold in the UK, including Azolla filiculoides (Fairy Moss), Crassula helmsii (Stonecrop), Hydrocotyle ranunculoides, Ludwigia grandiflora (Water Primrose), Myriophyllum aquaticum (Parrots Feather). Reputable dealers won’t stock these plants.
It is good practice to make sure you compost waste that you cut from your plants - or put it in your wheelie bin to be composted by the council. That way it won’t unintentionally get into rivers and natural ponds.
Get planting and enjoy your pond.