Every garden has its challenges. By learning to observe the environments that already exist and by planting plants that are adapted to growing in these locations we can work with nature rather than against it.
Damp soil can create a unique set of challenges for plants. Saturated soils suffer from a lack of oxygen and plants from these areas need special adaptations to their roots to be able to thrive in this environment.
The plants specified below are either marginals, (those that suit growing in shallow water), bog plants (that would grow in the waterlogged soils) or moisture loving plants that could grow slightly higher up a bank from the very edge of a pond or stream.
1. Rodgersia aesculifolia
This tough, moisture-loving perrenial plant is mainly grown for its deeply-veined, bronze tinted leaves (which look a lot like horse chestnut.) In mid-summer they produce tall flower spikes decorated with small creamy white or pink flowers. They look great teamed with the ‘metallic’ grey-green, upright and spiky leaves of Irises.
2. Astilbe chinensis
The deeply-cut foliage and tall, feathery, pink flower spikes of astilbe make it a strikingly attractive plant. They appreciate a moisture-retentive soil in a sunny spot to truly thrive, but are well worth finding the right spot for, as their attractive display will last from midsummer through until the autumn.
3. Iris pseudocorus
The yellow flag iris is a common plant in the UK and is found in many ponds, streams and areas with damp soil. The yellow, three-petalled flowers appear in late May and early June and are followed by seedpods that split open to reveal bright orange seeds in the Autumn. It can be a bit of a spreader, so you’ll need to give it plenty space, or alternatively lift and divide it every few years
4. Iris sibirica
A little further up the bank you could plant the Siberian Iris. They don’t grow in deep water like the yellow flag iris, but they do appreciate damp soil. They have narrower and more slender foliage than their native cousins, but are more prolific in bloom, producing a profusion of flowers in late May. One of my favourite varieties is ‘Tropic night’ which has deep blue-purple flowers with striking white throats and distinct markings
5. Persicaria polymorpha
This handsome, 2m tall perennial is much better behaved than some of its relatives, such as the the aggressively invasive Japanese knotweed. It appreciates growing in a fertile and moisture-retentive soil and will form large clumps of tall, hollow stems, with heart-shaped and pointed leaves. From early summer it is topped with spikes of frothy white flowers. As summer continues they will dry and fade to a bronze colour. Their silhouette provides height and structure to the borders through the autumn and winter.
6. Polygonatum x hybridum
Polygonatum are commonly called Solomon’s seal, as it is said their fleshy roots bear the mark of Solomon’s seal. Their arching stems have grey green, oval leaves arranged in opposing pairs, and pendulous, tubular or bell-shaped, creamy- white flowers, which are sometimes followed by black or red berries. Watch out for saw flies in late spring. Their caterpillars will happily shred the leaves in a few days quickly turning them to lacework.
7. Pontederia cordata
Pontederia is an aquatic plant, so prefers to be grown at the margins of a pond with its roots fully submerged in water. They form large clumps of glossy, grey-green, arrowhead shaped leaves. Their real attraction is during midsummer when they start to produce their striking blue flower spikes, which are loved by bees, butterflies and hover flies.
8. Matteucia struthiopteris
Ferns are commonly found in damp, shady areas and Mattecia struthopteris (The Ostrich feather fern) is one of the most dramatic ferns you can grow. In the spring, their bright, acid green fronds unfurl to form 1.5m tall ‘shuttlecocks’ of foliage. These will contrast well with large lush leaves of plants like hostas or darmera.
9. Darmera peltata
This moisture loving perennial has two distinctly different seasons of interest; unusual flowers in the spring, and lush foliage for the summer. In early spring the naked flower stems appear before any signs of foliage. The 60cm tall bright-red, hairy stems carry dome-shaped clusters of pink flowers. A few weeks later, the large, round leaves with heavily scalloped edges start to emerge and cover the area completely.
10. Primula viallii
The natural home for most primulas is on a damp meadow or riverbank where they have access to a plentiful supply of water. This extravagant variety has an unusual inflorescence with knee-high flower spikes that start to open from the bottom up. The lilac buds open to reveal a their deep-red centre, making it look almost like a small, purple red-hot poker.
11. Ligularia dentata ‘Desdemona’
Ligularia are striking plants with large, rounded bronze leaves that are deep purple on their undersides. They appreciate a deep, fertile and damp soil, with some sun. They will flower in late summer with large, orange daisy-like flowers. The soft foliage can be a delicacy for slugs, so can need a bit of care to make sure they don’t get eaten even before they get established.
12. Lythrum virgatum ‘Dropmore Purple’
If you are looking for some late summer colour for your damp soil border, you can’t go far wrong with Lythrum. This herbaceous perennial has a slender upright profile with long stems, covered with opposite pairs of narrow, pointed, mid-green leaves. From late summer into autumn they are topped with long bright purple flower spikes which seem to go on and on .
13. Salix alba
Willows are almost always found growing in damp spots. There is a huge range to choose from from the noble trees, to gnarled and prostrate shrubs. Some of the best to use in the garden are those with coloured stems such as the coral-orange of Salix alba ‘Britensis’, the golden yellow of Salix alba var. vitelina or the purple of Salix irronata. The display is best if the plants are cut back hard every other year to promote lots of vigorous young shoots with the strongest colouring.
14. Caltha Palustris
The Marsh Marigold is a delightful native plant to use in marginal or boggy areas. They start to produce large, buttercup like flowers from spring until early summer. These tough little plants will positively thrive on neglect, happily colonising an edge of a pond.
15. Hosta seiboldiana
Hostas are a favourite with many people for their lush foliage. They will flower, producing a spike of white or lilac blooms in mid summer. However, they are mainly grown for their thick fleshy leaves and the lush effect they produce. You do need to watch out for slugs though as they are one of the their favourite meals and their leaves can be quickly decimated. I tend to grow the grey-green leaved varieties which have thicker, tougher leaves and they seem to get less damaged.
16. Filipendula ulmaria
Sometimes known by its common name of meadowsweet, this tall perennial loves growing in damp areas. The serrated, pinnate leaves and red stems are beautiful but are even better when they’re topped with their foamy white flower heads in mid-summer. They produce salicylic acid – the same chemical as found in aspirin and Willowbark. They can also be used to make a cordial that tastes very similar to elderflower.
17. Trollius europaeus
This attractive herbaceous perrenial plant prefers deep, rich soils in sun or partial shade that don’t dry out. It forms a low mound of deeply cut, glossy, leaves and its rounded, buttercup like flowers are held knee high on thin stems, almost like tennis balls on skewers. It is native to marshy meadows, so would thrive in a border alongside moisture loving grasses, like Bowles golden sedge.
18. Zantedeschia aetheopica
You may know zantadeschia better as the calla lily. This herbaceous plant will produce a large clump of lush, arrow-shaped leaves and a profusion of flowers consisting of a single white petal wrapped around a yellow, finger-like spadix at the centre. They’re great for flower arranging but are also just as good in the garden and will grow in most moisture retentive soils.
19. Sagitarria sagatifolia
This delightful native plant would happily thrive when planted in the margins of most ponds. It has glossy, arrowhead shaped foliage and during summer will produce small sprays of white flowers with purple-centres that are a real favourite with bees, hoverflies and butterflies.
20. Petasites japonica
This giant version of the more common butterburr is originally from the far-east where it is known as Fuki and is fried in batter as a delicacy. The peculiar flowers appear before the leaves star to sprout in the spring. If they aren’t damaged by the frost, on a warm day they will fill the air with a delicate perfume. The enormous leaves appear later in the year, casting everything underneath into deep shade. This dramatic plant is best for larger gardens as it does have a tendency to spread if left unchecked.
21. Cornus alba
Most of us will be familiar with Cornus alba as it is extensively planted in landscape schemes for its brilliantly coloured, red stems throughout the winter. Many of us will have seen the bright orange-yellow stems of Cornus sanguinea ‘Winter beauty’ gracing the winter displays of garden centres across the land. To add to your palette of coloured stems for the winter, may I suggest the olive green Cornus stolonifera ‘Flavirmea’ as a good contrast that will thrive in damp soils.
22. Rheum Palmatum
Rhubarb is not just for jam and crumble, but can also make a great ornamental plant. Rheum palmatum has giant green leaves with deeply cut edges, pronounced veins and a shockingly deep red underside. The lush foliage gives a tropical, jungle appearance, but they are even more dramatic when the 2-3m tall flower stems open with plumes of tiny white or pink flowers.
23. Gunnera manicata
Gunnera is sometimes called ‘giant rhubarb’, which seems an apt description for this prehistoric looking plant. The pink tinged stems support enormous 1m across leaves with deep veins, like the scaly skin of a lizard. Don’t get too close though as every part of this plant is covered in spines. So if you have a garden large enough to let them do their thing, their incredibly dramatic appearance is best appreciated from a safe distance.
24. Butomus umbellatus
Also sometimes know as the flowering rush, this perennial grows best around the margins of ponds in water up to around a depth of 25cm. It forms clumps with twisted, narrow, grass-like leaves. In mid to late summer will produce a 1.5m tall, stiff flower stem topped by a striking umbel of fragrant, rosy-pink flowers which are loved by hoverflies and butterflies.
25. Hydrangea paniculata ‘Limelight’
As the name suggests, hydrangeas appreciate hydration, and will thrive on damp soils. This variety will eventually form a 2m bush. But instead of producing the rounded ‘mop-heads’ of the hortensia hybrids, hydrangea paniculata produces a broad, cone-shaped inflorescence of many tiny flowers. This initially appears bright, lime-green, then fades to creamy-white and eventually take on hints of pink as it ages. They can be left on the plant over winter. The bush just needs a light trim when the new growth starts in spring.
See all the sections in my Plant Guide here.