No damp squibs – twelve plants for boggy places

No damp squibs – twelve plants for boggy places

We usually think of boggy soil as a problem, with plants failing to thrive and succumbing to disease. Yet some of the best gardeners have built horticultural heaven on such difficult foundations. Beth Chatto’s Garden in Essex and the RHS garden at Harlow Carr in Yorkshire have fine examples. Find inspiration here: https://www.rhs.org.uk/gardens/harlow-carr/garden-highlights/streamside

It’s really quite difficult to change the character of soil in an area that’s permanently wet. You can dig in organic matter and grit but you need an awful lot. Alternatively, artificial drainage can be put in but this is often a major operation. Much the better option is to embrace the conditions you have and work with, rather than against, them. While there are many plants which won’t be suitable, there are also a surprising number that are.

We’ve selected just a few that should thrive in areas of soil that are poorly drained and never dry out.  We’re not talking pools of water that never disappear (although there are ways of adapting to that too), just soil that is always slightly soggy. They’re listed in order of flowering time, to give you some idea of how your boggy garden can look good throughout the year.

Bog plants like nutrient-rich soil so it’s a good idea to add plenty of leafmould or compost when planting. If your soil contains a lot of clay, add a handful of grit to each planting hole too, this will help drainage.

Darmera peltata

You’ve probably come across spectacular Gunnera manicata or giant rhubarb – it’s not a plant you forget if you’ve seen it. With rough, spiny leaves up to 2m in diameter and potentially growing to 2.5 tall and 3m wide it’s a plant that’s only at home in sizeable gardens.

Darmera peltata, however, offers a similar but down-scaled effect. Rather less thuggish, the leaves are glossy, softer and rounder and on mature plants only grow to about 50cm across. It also has striking umbrella-like heads of pale pink flowers which shoot up in spring before the foliage. Much smaller, it reaches only about 1.2m in height. Grow in full sun or part shade.

Primulas

No boggy planting would be complete without glorious Primula Candelabra hybrids and the similar pale purple Primula denticulata. Lollipop-like in both shape and colour, they’ll add zing and zest to your beds and borders in shades of pink, red, purple, yellow and orange as well as white. With late spring and early summer flowers and at 45cm – 1m tall, they generally prefer dappled shade but will tolerate full sun. Primula japonica ‘Miller’s Crimson’ has deep magenta flowers, P. beesiana is lilac/pink) and P. bulleyana  is apricot. They thrive in wet conditions but make sure the crown and leaves don’t become submerged in winter. At their best when planted in groups.

Marwood Hill Garden in North Devon has a marvellous display of them and is well worth a visit: https://marwoodhillgarden.co.uk/

Myosotis scorpiodes (water forget-me-not)

A more watery relative of the delightful common or garden forget-me-not and similar in appearance, this low-growing plant provides seasonal ground cover between taller plants as well as early summer sky blue flowers. Thriving in sun or part-shade, it grows to 20 x 40cm.

Lysimachia nummularia ‘Aurea’ (creeping Jenny)

Another valuable ground cover plant which has the advantage of being evergreen. Small yellow flowers appear among the golden yellow foliage from early to late summer. An excellent winter gap-filler.

Elegant iris

You may have seen our native yellow flag iris (Iris pseudacorus) growing in and near ponds. More unusual is Iris ensata, the Japanese water iris, which has rich deep purple flowers in midsummer. Growing to approximately 80cm tall, it’s happy in full sun or part-shade.

(Did you know? Parts of the yellow flag iris were traditionally used to dye both tartan and tweed, the roots creating dark blue and black colours and the leaves bright green.)

Astilbes

The feathery plumes of astilbes add drama to partly shaded areas in mid-late summer. In shades of deep pinkish red through to white, there are many species and cultivars varying from small plants for the front of the border to more impactful plants up to 2m tall. Their common name – false goatsbeard – merely adds to their charm!

Lythrum salicaria (purple loosestrife)

For adding height to beds and borders this majestic 2m tall wildflower is a winner. Found on the banks of streams and rivers in the wild, the tall spires of lilac pink flowers bloom from mid- to late summer in full sun or part-shade. It’s also a pollinator magnet – bees, moths and butterflies love it – so you’ll be doing nature a favour as well as yourself by adding it to your boggy space. As you might expect from a wildflower it’s tough and is said to tolerate drying out, so is useful if you have heavy clay soil. Self-seeding at will, it can become invasive, so keep an eye on it and remove flowers as they fade if it starts to take up too much space.

Ligularia dentata

This slightly unusual-looking plant has large deep yellow to orange daisy-like flowers during summer and early autumn. The new growth of its substantial, slightly jagged leaves is purple becoming deep green as they mature. Their undersides, however, remain purple. Height and spread 1 x 1m. Ligularia ‘The Rocket’ has spires of smaller, more delicate-looking flowers which can reach 1.8m tall. Full sun or part–shade.

Lobelia cardinalis

Very different from the half-hardy annual bedding lobelia that you’re probably familiar with, this is a taller, stately perennial with eye-catching scarlet flowers from late summer to autumn. Native to the American continent where it can be found from south-eastern Canada all the way down to Colombia, it grows well in sun or part-shade. Height and spread 90 x 30cm.

For the spaces in between your flowering herbaceous perennials, interplanting with non-flowering plants, especially evergreens, will add some structure and complement and highlight all those dashing colours.

Ferns

Evergreen Woodwardia orientalis does best in part-shade and has a height and spread of 1.5 x 2m. The more delicate-looking Athyrium filix-feminina is smaller but will die back in winter.

Grasses

Carex elata ‘Aurea’ is a very tolerant evergreen with bright gold and green striped leaves. Growing up to 75cm high, it’s happy in sun or part shade. If you’d like something larger, plant Juncus effusus (common rush). Another evergreen, it grows up to 1.5m and is happy in full sun or part-shade.

Trees

Large water-loving willows make stunning features for correspondingly large gardens and will certainly suck up lots of moisture but the smaller pussy willows don’t like overly wet conditions. Our smaller native hawthorn, Crataegus monogyna, however, is exceptionally tolerant of many conditions, including boggy soil. Left to its own devices it reaches about 8m tall but responds well to regular pruning if you prefer to keep it in check. Smaller forms such as C. monogyna ‘Compacta’ will only get to about 2.5m in height.  Its delightful spring flowers will feed the pollinators and its berries will feed the birds too. What more could you ask for?

You’ll find some more ideas for plants that will do well in soggy areas here:

https://www.gardenersworld.com/plants/10-plants-to-grow-in-bog-gardens/

https://www.rhs.org.uk/plants/for-places/bog-gardens

And a word about moss

If there are wet areas in your garden you’ll probably have moss, perhaps on tree trunks and branches, perhaps in the lawn, or perhaps on benches and stone features. It’s often seen as the enemy by gardeners but I would encourage you to encourage it. It soaks up moisture, locks up carbon and is a thing of extraordinarily intricate beauty.

Not only does it make sense to work with the natural conditions in your garden, the plants in this instance will reward you, helping to ease your problem by drinking some of the excess water. You’ll probably find that there are pockets within your garden with different levels of moisture and that its sogginess varies from season to season and even from year to year. Gardeners have different experiences so you may find yourself experimenting to find out what works well in your particular space. However you decide to do it though, keep in mind the core principle of gardening: right plant right place.