Plants for Wet Ground: What to Grow Where the Soil Never Dries

Wet ground grows plenty, as long as you stop trying to grow the wrong things in it. Black poplar, willow, elder, guelder rose and aronia thrive where water sits; blackcurrants, rhubarb and comfrey are happy in heavy, moist soil; water mint, lovage, sweet cicely, hosta and ragged robin fill the ground layer. What wet soil will not grow is apples, plums, figs, lavender or any of the Mediterranean herbs, and the sooner you accept that the sooner the garden starts producing. This guide covers why soil stays wet in a climate like Ireland's, how to tell moist from waterlogged, what to plant in each, and when it is worth raising the ground instead. It applies anywhere with high rainfall and heavy soil, from Kerry to the west of Scotland to Brittany.

Short on time? Aronia is the one fruit bush that crops heavily in wet ground, and it can go in bare-root any time this winter that the bed is not actually under water.

Why Soil Stays Wet in a Climate Like Ireland's

Three things combine. The first is rain: the west of Ireland gets 1,000 to 1,400 mm a year, more in the mountains, and even the drier east gets 750 to 1,000 mm, spread over 150 to 225 wet days, so the soil rarely gets a chance to dry out between October and April. The second is what the ice left behind: most lowland Irish and British soils sit on glacial clay, which holds water the way a saucer does. The third is us. Lawns rolled by machinery, gardens on new housing estates where the topsoil was scraped off and the subsoil compacted by diggers, and beds walked on in winter all lose the pore space that lets water drain.

The result is a high water table for half the year and standing water after any heavy rain. Our guide to improving heavy soil covers the slow work of building structure. This post is about what to plant while that work goes on, and in the places where it never will.

Moist or Waterlogged? The Test That Decides

The distinction matters more than anything else in this guide. Moist soil is damp to the touch all year, drains after rain within a day, and grows an enormous range of plants, including most fruit. Waterlogged soil stays saturated for days or weeks, and only specialists cope with it. Dig a hole 30 cm deep in winter, fill it with water, and time it. If it empties within a few hours, the soil is moist and well drained. If it is still half full after 24 hours, it is poorly drained, and if it fills by itself from below, you have a high water table and the plants in the first two sections below are your list.

Look at the soil you dug out as well. Grey or blue-grey clay with rusty orange mottles, sometimes with a sour smell, is soil that spends part of the year without oxygen. Soil scientists call it gley, and it means the ground has been waterlogged for a long time, whatever it looks like in August.

What Waterlogging Does to Roots

Roots breathe. They take oxygen from the air spaces between soil particles, and when those spaces fill with water for more than a day or two the root tips suffocate, then rot, then the fungal diseases move in. That is why a fruit tree in waterlogged ground dies from the bottom up over a couple of wet winters, with the leaves yellowing and dropping early in summer long before anyone thinks of looking at the roots.

The plants that cope with it have ways round the problem. Willows, poplars and alders grow air channels in their roots that carry oxygen down from the stem, and they can grow new surface roots fast when the old ones drown. Marsh plants like water mint and ragged robin keep their roots shallow, in the few centimetres that drain first. And some shrubs, aronia and guelder rose among them, come from swamp edges and simply tolerate a lower oxygen level than an apple ever could.

Trees and Shrubs for Wet Ground

Black poplar (Populus nigra subsp. betulifolia) is the tree for the wettest corner. It is possibly native to Ireland, rare, fast to 30 m, and at home on riverbanks and floodplains where the soil is saturated for months. A black poplar does more to dry a boggy patch than most people expect, because a mature tree moves hundreds of litres of water a day in summer. Plant it well away from buildings and drains.

Willow does the same job on a smaller scale and gives you poles, basket material and the earliest catkins of the year for bees. Our biomass willow is cut to the ground every two or three years and regrows 2 m or more a season in wet soil.

Elder (Sambucus nigra) grows in ditches and wet hedges across Ireland and crops flowers and berries within two years of planting. An elder tree in wet ground is the fastest route to a productive plant on a difficult site.

Guelder rose (Viburnum opulus) is the native shrub of fens and riversides: white lacecap flowers in June, red berries for bullfinches in autumn, and leaves that turn claret. Guelder rose grows 3 to 4 m and tolerates ground that is wet for most of the winter.

Aronia (Aronia melanocarpa) is the fruit bush for wet soil. It comes from the swamp edges of eastern North America, crops heavily in ground that would kill a gooseberry, and needs no pruning. The berries are too astringent raw and good in juice, jam and mixed with sweeter fruit.

Alder and hawthorn also belong on this list, and we grow both in small numbers; ask if you need them.

Fruit and Vegetables for Heavy, Moist Soil

These want moisture and tolerate heavy clay, but not standing water. Plant them where the test hole drained within a day, or on a mound in wetter ground.

Blackcurrant tolerates wetter, heavier soil than any other soft fruit and crops better for the moisture. A blackcurrant on a 20 cm mound in a heavy bed is a reliable 3 to 5 kg a year.

Rhubarb wants the richest, dampest soil in the garden and sulks in dry ground. A rhubarb crown at the wet end of a bed, raised just enough that the crown itself sits above winter water, will crop for fifteen years.

Lovage and sweet cicely are the herbs for damp ground. Lovage grows to 2 m and gives celery flavour from a single plant; sweet cicely takes damp shade and sweetens stewed fruit.

Hosta is a damp-shade plant from Japan whose spring shoots are eaten as a vegetable there. A variegated hosta in heavy, moist soil under a tree gives a picking of shoots in April and a handsome plant all summer.

Ground Cover and Wildlife Plants for Wet Soil

Water mint (Mentha aquatica) is the native mint of Irish ditches and pond margins. It will grow in a few centimetres of standing water, flowers lilac in August for bees and butterflies, and makes a sharper tea than peppermint. Water mint is the plant for the corner that is never dry.

Comfrey (Symphytum x uplandicum, Bocking 14) thrives in moist, heavy soil and turns it into free fertiliser: four cuts a year of leaves for mulch, compost and liquid feed. Comfrey also pulls nutrients from deep in wet clay with a root that goes down 2 m. Our comfrey guide covers the cutting routine.

Ragged robin (Silene flos-cuculi) is the pink wildflower of wet meadows, flowering in May and June for bees and hoverflies, and ragged robin seeds itself through damp grass once established. Coltsfoot flowers yellow in February on bare wet clay before its leaves appear, and coltsfoot is one of the first nectar sources of the year. Meadowsweet, marsh marigold and purple loosestrife complete a wet wildlife corner, and our pollinator plants guide has more.

What to Avoid in Wet Ground

Apples, pears, plums, damsons, cherries, figs and most nut trees will fail in waterlogged ground, however well they do in heavy moist soil on a mound. Raspberries rot. Strawberries rot. Lavender, rosemary, thyme and sage die in their first wet winter. Asparagus and globe artichokes need drainage. Blueberries are the odd case: they like moist, acid soil and come from the edges of bogs, but they still need the water to move, so a wet bed with a slope suits them and a stagnant one does not. If a plant comes from a Mediterranean hillside or a dry prairie, keep it off the list.

When to Change the Ground Instead

Sometimes the better answer is to lift the plant above the water. A mound of soil and compost 30 cm high and 1 m across puts a fruit tree's root collar and most of its feeding roots above the winter water table, and apples, plums and damsons will grow on a mound in ground that drowned them at ground level. A raised bed 30 to 40 cm deep does the same for vegetables and strawberries. For the wettest patches, a hugelkultur bed built on logs raises the growing surface half a metre while the logs below soak up and release the water.

Drainage is the last resort, because it moves the problem rather than solving it. If you do drain, send the water somewhere useful: a pond at the lowest point of the garden takes the winter overflow, grows watercress and water mint, and does more for wildlife than anything else you can add.

FAQ: Plants for Wet Soil

What fruit grows in wet soil? Aronia and elder crop in genuinely wet ground. Blackcurrants, rhubarb, guelder rose and, with a slope, blueberries do well in heavy moist soil that drains within a day. Apples, plums, raspberries and strawberries need their roots out of winter water, so plant them on a 30 cm mound or in a raised bed.

Can I plant a fruit tree in waterlogged ground? Not at ground level. Build a mound 30 cm high and 1 m across from topsoil and compost, plant the tree on top with the graft union above the mound, and mulch it. Damsons and plums tolerate the heaviest soil of the fruit trees; figs, apricots and cherries are the fussiest about drainage.

What tree soaks up the most water? Black poplar, willow and alder. A mature black poplar or willow moves hundreds of litres of water a day in summer and can noticeably dry a boggy area. Plant them at least 10 to 15 m from buildings and drains, because the same roots that drink the water will find a pipe.

Will comfrey grow in wet ground? Yes. Comfrey prefers moist, heavy soil and tolerates ground that is wet for much of the winter, though not permanent standing water. The Bocking 14 variety is sterile, so it will not seed around, and it gives four cuts of leaves a year for mulch and compost.

How do I know if my soil is waterlogged? Dig a 30 cm hole in winter, fill it with water and time the drainage. Empty within a few hours means well drained; still half full after 24 hours means poorly drained; filling from below means a high water table. Grey or blue clay with orange mottling in the hole confirms the ground has been without oxygen for long periods.

Planting for the Water You Have

Earthling Plants grows every plant in this guide at our nursery in Co. Wicklow, on a wet hillside of our own, and ships across Ireland, the UK and the EU. If you are designing a whole site around difficult ground, the method for reading a plot and placing each plant where it will thrive is in The Complete Food Forest Blueprint.

Related reading: Hugelkultur: how to grow a garden on rotten wood · How to grow comfrey · The best plants for an edible hedge