Plants for Damp Sites
When it comes to damp areas in your garden you need to be very careful about what plants you choose. Damp areas do not suit many plants and if you choose the wrong plants here they are likely struggle if not die. Your plant selection is limited in these conditions.
What defines a damp area?
The rate at which water drains from your soil will determine this. You can test your soil's drainage by doing one simple test:
- Dig a small hole 50cm deep
- Fill the hole with water
- Wait one hour
- Come back & determine the amount of water remaining
If the find the hole is...
- Still mostly full of water - Your soil has poor drainage & site will be considered a damp area
- Half full or empty – Your soil has moderate drainage
- Mostly empty - You have a free draining soil
Before listing plants that are suited to damp soils, we would first like to recommend some soil improvements that can be made to damp sites to make them more suited to all garden plants.
Drainage work can be carried out to increase the water flow rate off your site. Ideal soil conditions would have 33% moisture, 33% air & 33% matter. 33% matter would include sand, silt, clay, minerals & organic matter. Air is essential in soils as it allows roots to respire and soil insects & micro-organisms to breath. In damp soils, air content is reduced as water levels increase. This means damp soils have less insects & micro-organisms.
Some basic drainage tips
- Only work your soil when it is as dry as possible
- Avoid walking on your soil in damp conditions
- Install a French-drain to take water
- Ensure the drain is at least 30cm deep & slopes away from your site
- The presence of lak / marl / clay soils will further impede water flow & drainage
- To improve water flow in these conditions, you can cultivate your soil & add drainage material such as grit or organic matter
Plants for damp site
There are about 20 excellent plants for damp areas and we have listed them for you here. The groups are divided into plant category groups
- Betula Pubescence’s - Downey Birch – Native to Ireland
- Liquidamber Styraciflua
- Amelanchier Canadensis - 'Snowy mespilus'
- Hydrangea Paniculata
- Phormium Tenax - 'New Zealand flax'
- Salix ('Willow) – Native to Ireland
- Gunnera Mannicata
- Rheum (Ornamental rhubarb)
- Phyllostachys (Bamboo)
- Cornus (Dogwood)
- Viburnum Opulus (The Guelder Rose) – Native to Ireland
- Sambucus (Elder) – Native to Ireland
- Acorus Calamus (Sweet Flag)
- Hosta (Plantain lily)
- Carex (Sedge)
- Japanese Water Iris
- Hemorocallis - 'Day lily'
- Lysimachia – (Creeping Jenny)