Planting in water uses 3 types of pond plants:
These each live in a different area of the pond and have a different function to each other.
1. Submerged plants:
If a plant is totally submerged below the water it has most adaptations to water existence.
They have little or no support cells in their stems or leaves as they are supported by the water around them. If removed from the water they will hang limply and will wilt very quickly so all stem and leaf surfaces need to be kept damp or wet.
All the plant surfaces are able to absorb water, nutrients and dissolved gases directly from the water. Submerged leaves are often highly divided creating a very large surface area for absorption and photosynthesis.
Oxygenating plants are dropped into the pond either with or without a lead strip to bunch them dependent on the species of the plant. They do not need to be planted up as they float freely in the water, moving up and down according to the water temperature.
2. Floating plants:
These can be rooted deep in the pond but with floating leaves (waterlilies, Water Hawthorn) or some are free floating (Frogbit).
In both waterlilies and Frogbit the breathing pores that allow gas exchange are only on the upper surface.
The waterlily plant ‘breathes’ through these pores and this is the reason waterlilies do not like to be placed under constantly splashing water (it blocks their noses!). Waterlilies grow from the deep water and hold the leaf on the surface via stems with hollow tubes enabling air transfer necessary for the roots of the plant.
Covering the surface water is an important task of surface cover plants so that the water temperature remains cool for fish and wildlife. Shade from the leaves also helps reduce algae growth. Flowers are an added bonus.
3. Shelf plants:
These grow from below water level with stem, leaves and flowers showing above the water. These plants are rooted either in a basket and placed on a shelf or ledge of a pond with man-made liner or planted in the edge of a clay pond. These plants use nutrients to put on growth and flower at different times of the season that create the visual interest and wildlife habitat of the pond you enjoy.
2 types of shelf plants:
- emergents or uprights – their stems and flowers are held well above water level
- rafting plants – they have horizontal growth that rafts across the water surface.
You need a combination of all 3 of these plant types to make a successful and balanced pond area.
Always remember that plants placed in water each like certain depths of water above their basket and getting this right for them will be crucial for their survival and success.
Potting plants for a pond:
Both aquatic compost and mesh baskets are a must for any plants that will be submerged into water in a basket so ours are correctly planted up ready for you to lower into the water when they arrive.
Our pond plants and waterlilies are potted into a clay/loam mix aquatic compost.
You cannot use ordinary, multipurpose potting compost for pond plants as this is too light and will contain peat (which will continue to decompose when submerged in water and rot the plant roots) or coir (which will float away when submerged).
Aquatic soil is available in bags in most garden centres and should be brown in colour and not black.
When you divide or repot pond plants into new, larger mesh baskets and aquatic soil you should add a fertiliser tab too.
Pond plants grow in mesh aquatic baskets. These mesh baskets are available in various sizes and allow water to circulate through the compost allowing the transfer of oxygen and nutrients between the water and the plant. The compost should not wash away through these fine holes as the plants are rooted and the root growth will hold the soil together.
The mesh holes allow the plant roots to escape from the cramped conditions inside the basket and stretch out into the water to gain more contact between the root surfaces and the water to soak up even more nutrients from the water. Some water plants, like waterlilies, can have as large a root spread as their leaf spread is on the surface of the water.
As a plant grows it should be moved into a larger mesh basket and the space filled with aquatic compost or washed gravel.