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plants for boggy/swale area in NH

Posted by klew Z7b/8, NE PDX, OR (My Page) on
Wed, Jul 25, 12 at 18:37

Greetings, all. I'm writing from Portland, OR, regarding my sister's yard. She lives in the Nashua area of NH. Much of the three acres is forested, but the house has beds and "lawn" (assorted grasses, yarrow, clover, etc.). There is a boggy area, what we in PNW call a swale, on one side of the house that is permanently damp/wet, shaded for part of the day but a bright, high shade.

If she lived here, I'd help her plant camus and other PNW natives.

What northeastern plants would you recommend? Must be able to naturalize, survive the weather, etc.

Thanks in advance for info and input.


Follow-Up Postings:

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RE: plants for boggy/swale area in NH

What sort of thing are you looking for? Shrubs, trees, perennials are all possibilities. What is there now? Is it something that is going to be difficult to persuade to make room for something else?

A simple search on northeastern wetland plants will give several lists.


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RE: plants for boggy/swale area in NH

I posted about this a few years back and got some good recommendations, but for the life of me I can never ever find that thread when I need it. I even had a follow-up thread but can't find that either!

Anyway, depending on what you are looking for, this is what I planted in a similar situation.

cornus alba
viburnum
itea
clethra
ligularia
astilbe
lobelia (cardinalis and siphilitica)
japanese iris
siberian iris
louisiana iris
salix
ilex
hibiscus
swamp azalea
cephalanthus occidentalis
caltha palustris
bog rosemary
filipendula (can't think of which one off the top of my head)

there was a hydrangea, peony, dicentra and hostas already there, as well as ferns.

Most things are doing well. Some are doing great, others are so-so. The hibiscus and swamp azalea are second year (planted last year as very small plants) and are struggling a bit, and the clethra keeps flopping over, but almost everything else is doing well.

Dee


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RE: plants for boggy/swale area in NH

If I recall, you asked about plants for other areas of you sister's yard a year or two ago. If you have started her plantings, would you be willing to post some photos?

Adding organic matter to the bed will help even out moisture as will mulch to make this a more successful garden. Here are some plants (some of which are natives so should be relatively easy) that are happy in a damp area. Many of these Dee mentioned, but here are comments based on my experience growing them.

Shrubs:
- Rhododendron viscosum (swamp azalea) has white to pink early summer flowers (just fading now) which are vanilla scented. This will only flower if it gets at least some sun. It gets some fall color also. Native
- Clethra alnifolia (Sweet pepperbush or summersweet) has spikes of white to pink late summer flowers and clear yellow fall color. Some of the selections of the species are better than others for impact: Ruby Spice has pink flowers or Anne Bidwell sports clusters of white spikes or Sixteen Candles is compact with large white spikes. Flowers better in more sun, but tolerant of sun, shade, wet or dry. Some varieties will sucker. Native
- Ilex verticillata (winterberry deciduous holly) has showstopping fall to early winter scarlet berries on bare branches, but needs at least half day sun to flower and berry well. Winter Red holds the berries the longest, according to research I've read and is the variety I grow, though only now getting large enough to berry. They may sucker some. Be sure to plant the appropriate male in an unobtrusive place in order to get berries. Native
- High bush blueberries like some extra moisture, but not standing water, so could be planted in the less wet areas. Spring flowers, berries, fall color. Native
- I think any of the shrubby dogwoods are pretty tolerant of wet feet and you can find them with various shades of red or gold twigs for winter interest as well as with variegated foliage. some native, some not, but all easy. Some will sucker.
- There are various dwarf (4-12 feet rather than 30 feet) forms of Thuja occidentalis, eastern white cedar AKA arborvitae which grows in swamps if you want some evergreen interest. Deer like this if you have many of them . I haven't had any issues with them being eaten by deer. Native
- Andromeda polifolia (bog rosemary) is a lovely low-growing evergreen, but can be fussy if it doesn't get even moisture and organic, acid soil. It is fine with part sun and has pink bells in spring and narrow, bluish foliage. Native
- Ledum groenlandicum AKA Rhododendron groenlandicum (Laborador tea) is a low-growing plant with leathery leaves and clusters of small white flowers in spring. Native
- Rosa palustris is a native wetland rose with single pink flowers in early summer and nice scent. The hips are decorative also. Native

Perennials:
- Caltha palustris (marsh marigold) has bright yellow spring flowers in wet areas, and the foliage will die back in summer if it's dry. It seems to do well in some shade since it grows and blooms largely before the trees leaf out. Native
- Osmunda cinnamonea & O. clatoniana (cinnamon & interrupted ferns) both provide statuesque foliage for shade to part sun. They tolerate wet soil, but are happy if the soil is normal moisture also as long as it doesn't get both sunny and very dry. Native
- Osmunda regalis (royal fern) is a tall lacy wetland fern with beautiful clear yellow fall foliage and requires wet soil all the time. Native
- Veratrum viride (false hellebore) has large, pleated foliage that would make a good hosta substitute and needs to be in a wet area. Everywhere I know that this grows is in the shade. I've never seen it at a regular nursery, but you might find it at a wetland mitigation nursery or specialist nursery for wetland plants. Native
- Camassia is a PNW native that likes moisture and has blue spring flowers. It can be purchased through good bulb suppliers like Brent and Becky's Bulbs www.brentandbeckysbulbs.com/
For late summer bloom, there are several large statuesque plants, including Eupatoriums and Veronias, but all need at least half day sun and are happiest in full sun. all native
Eupatorium purpureum (now renamed by botanists as Eupatoriadelphus maculatus, common name joe pye weed) has clusters of mauvy purple fringy flowers in late summer.
Eupatorium perfoliatum (boneset) has similar clusters of white flowers in August.
Veronia has deeper purple flowers. Vernonia fasciculata (prairie ironweed) is tolerant of moist and dry conditions as is V. noveboracensis (New York ironweed.)
- Iris versicolor (blueflag iris) is a native iris that I've seen blooming in full shade. It will bloom better in some sun. (As a side note, don't plant Iris pseudacorus, yellow flag, as it is an non-native that is invasive in wetlands.) Japanese and Siberian irises are happy with wet soil and will be fully hardy for you since I can grow them about an hour north of you. I'm not sure if Louisiana iris is hardy enough since I've seen various assessments of hardiness, but not grown them.
- Lobelia cardinalis (cardinal flower) is a native that grows along streams and river banks, but will also grow in ordinary garden soil. I'd avoid Lobelia syphilitica (great blue lobelia) because IME it is a rampant self-seeder unless one always deadheads; ten or so years ago I removed them from by garden, but I am still finding volunteers in the garden, the lawn, the gravel drive, etc.
- Clematis viriginiana grows along the steam on the floodplain in wet soil here, so should be fine for you. It will bloom less in less than full sun, but as long as it has more than 5 hours of sun should be fine. It has lots of tiny white flowers in late summer, sort of like sweet autumn clematis.
- Clematis crispa is also native to swampy areas and has smaller bell-shaped flowers in shades of white and light lavender and mauve.
- Clematis glaucophylla has pink and cream bells and also is native to lowlands along streams.
Here is a site that will give you information about some of these native (though not all to NH) clematis: http://www.clematisviorna.info/
and here is a place that often carries some of these clematis http://www.gardenvines.com/. (You can request to be informed via email when they are back in stock since they are all currently out.)
I tend to grow these small-flowered clematis near large shrubs so they can climb and ramble around whatever is nearby. They seem to play well with others as long as I let the shrubs get well-established first, so I tend to plant my clematis after the shrubs are 2 or 3 years old. They will also grow on a traditional obelisk or trellis. All want to get cut to about a foot sometime during the non-growing season, though they will do fine if not cut back, just will bloom higher on the plant.

My favorite ground cover for average to wet garden soil and full shade to full sun is common cranberry, Vaccinium macrocarpon. It is another native, with tiny evergreen leaves, equally tiny pink flowers, and startlingly large red berries which persist until spring. It weaves well among other plants and never get taller than about 4 inches, though it may spread 2 or 3 feet in all directions, rooting as it spreads. It doesn't smother other plants, so it's a great groundcover to plant, though it will need mulch to prevent weeds coming up through it. It is denser in more sun.


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RE: plants for boggy/swale area in NH

Ah, nhbabs, you've put me to shame, lol - while we had the same ideas, I always rush too much to get the info out, and because you took your time and put some effort into it, your post is much more informative.

I should say I second the warning on the lobelia siphilitca. I am not *unhappy* that I planted it (yet!) as it is a beautiful flower, does well here, and we have a lot of space to fill, but I do keep an eye on it and pull it from where I don't want it. Truth be told, I might not have planted it if I had known its tendencies, but as of yet I don't regret it - especially when it's in bloom!

And thanks for the recommendation of the cranberry groundcover. Do you think an expanse of this would inhibit an expanse of jewel weed from growing? I see you say it needs mulch in addition, but does it help with weeds at all?

I put down a heavy mulch of (barely) shredded leaves every fall and even in spring, if I have any left, to help control the unwanted stuff (and always wonder if I am upsetting the balance of this swamp area as I do it. I don't think I'm doing much, if any, damage, as it is surrounded by woods anyway, but I try to be so careful around wet areas). Jewelweed is easy enough to pull, and I defeat the purpose by letting it grow (and therefore reseed) in the wooded area behind the garden (but I just can't weed the entire world, lol!), but there are a surprising amount and variety of weeds in this bed - grasses, some kind of large-leafed, tap-rooted plant (whose name escapes me at the moment), some skunk cabbage, that horrid wild raspberry (ouch!), pokeweed, other unknowns and this year in particular, lots of poison ivy.

Forgot to add that of course native asters do well in these areas (I just wish they would stay where I want them!) and also native goldenrod. And across the creek from this bed looks to be some kind of eupatorium that is growing wild. I'm not sure if its my friend's property or not, and even if it were she didn't plant it, but it's a nice backdrop to her garden. It looks like eupatorium to me, but it's early, spring-blooming, and the white flowers are held on kind of a flat head, so I'm not quite sure.

Dee


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