How to correct soggy soil conditions, build a berm and plant in boggy areas
Plus 29 plants that thrive in wet soil
Hello, friends!
I delayed this week’s email by a day because I wanted to ascertain what your garden needs would be after the weekend’s storm.
We weathered Henri without any damage here on the north shore of western Nassau County, NY. I hope you and yours are well, too.
But even without sustaining any damage, most of us on the mid-Atlantic and Northeast coast — and elsewhere — are dealing with wetter-than-usual soil this summer, which was further compounded by the deluge.
Those of you who live in areas with heavy, clay soil are likely too familiar with the condition, wet summer or not. Ditto for those gardening at the bottom of a hill, near storm drains and downspouts, in boggy areas or dealing with compacted soil, poor drainage or a high water table.
If not corrected, these conditions often lead to root rot and other diseases because too much moisture robs roots of oxygen, which is essential for plant life.
The first remedy to implement would be the incorporation of compost. Compost is the single best thing you can do for any garden. It’s a virtual cure-all, improving the drainage of clay, increasing the water-holding capacity of sand and adding a gazillion nutrients to all soil types — it even reduces (and often eliminates) the need for fertilizer. You simply can’t have too much compost.
Ideally, you’ll add 4 inches of compost to the entire garden area and work it into the top 6 inches of soil before planting. But if the garden is already established, that likely won’t be possible without disturbing existing plantings, so I’d recommend using compost as mulch and adding it to the backfill for each planting hole as you add new plants. Backfill with a 50/50 mix of garden soil and compost; you can use the other half of the soil removed from planting holes elsewhere in the garden. We all have holes and depressions that need filling.
If your garden is situated in a cavity, you can redirect water that collects there by digging a trench alongside the bed. Slope the trench, which should be 4-6 inches deep, away from the garden and fill it with pea gravel or stones. Excess water will flow down the trench and drain through the rocks.
Alternately, you can plant on a berm, or elevated gardening hill (see the photo at the top of this page). To build one, you'll need to create a base with soil (here's a use for your extra backfill), stones, sand and/or other fill, then cover it with soil, taking care to firm it periodically to ensure its stability.
It helps to sketch out the shape and size you’d like before starting. Be creative — berms can be crescent-shaped, asymmetrical or taller on one side. Then delineate the area with a garden hose until you’re happy with its size and shape.
Berms are typically four to five times as tall as they are wide, topping out at 18-24 inches then gradually sloping down to ground level on all sides. Half the height of your berm should be fill, topped with an equal amount of soil for planting in.
Water the berm after it’s completed and you’ll likely notice more depressions. Best to find, fill and firm them now before planting.
If your condition is uncorrectable — or if you simply aren’t able to implement either of the above remedies, stick with plants that prefer soggy soil. There are plenty to choose from:
Water-loving perennials include calla lily, swamp mallow, swamp milkweed (pictured above), butterfly weed, camassia, bee balm, sweetspire, fern, Joe Pye weed, lobelia, Weigela, iris, Euphorbia, hosta and astilbe.
Shrubs that tolerate muck include smooth hydrangea (pictured above), buttonbush, blackthorn, elderberry, spirea, viburnum, berberry, andromeda and clethra.
There are some trees, too, that do well in standing water. Consider pin oak, pear, red maple, river birch (pictured above) and willows.
👉👉If you’re enjoying this newsletter, why not share it with a gardening friend?
💡 If you do one thing this week…
Start hitting up nurseries and garden centers for sales on perennials. Before buying, gently slip plants out of pots to ensure roots are healthy and not pot-bound; they might have been sitting there since Spring.
👏 Sunday shoutout
Shouting out to everyone who submitted photos for the 2022 Garden Calendar Photo Contest! I received hundreds of beautiful images, and it’s going to be extremely difficult to pick just 12. Winners will be announced in September, so stay tuned!
📧 Send me your feedback!
I welcome your comments and suggestions, so please send them along — as well as any topics you’d like to see covered and questions you’d like answered in the Ask Jessica section.