5

Problem

Anyone on the East Coast of the US is probably aware of what a rainy year it has been. As of my writing this, the last six months in Northern Virginia have had more rain (1149mm at Dulles Airport) than the yearly average (1021 mm).

This year's rain has exacerbated the swampy conditions of my backyard. After heavy rainfall, my yard gets so swampy that I can barely walk back there. Work boots tend to punch holes in the turf, and if I slip in the slick conditions, I'll tear up the grass. This year, the whole backyard has been so wet that I have not actually mowed a single time. The yard has been so soggy, that no one has been in it since April. I am barely exaggerating when I say that the soil has the consistency of mayonnaise.

The conditions

My backyard is more or less designed to be swampy. First, it is entirely in the shade of the house or backyard trees; it gets at most a few hours of partial sun a day. Second, most of it is at a 10% of higher grade, facing north-west, which is mostly away from the sun.

I thought the grade would help water to run off, but that hasn't been the case. Having dug some fenceposts, I can tell you the soil has about 4-6 inches of topsoil, followed by 1-2 feet of red dirt, then a pretty solid clay layer that is hard to dig through. I believe the problem is that drainage through the red dirt is slow, so the upper topsoil layer ends up super saturated.

What I need

I'm looking for some lawn-like vegetation to help control the swampiness problem. I am wondering if there are plants that can either

a. help to promote drainage, perhaps with deeper roots that let water get through that red dirt b. help solidify the soil someone, so that it can be walked on even if it has rained for a few days.

The grass that came with the house when I bought it (mostly fescue, I think) has survived for at least 4 years. I have no trouble with trying a more mixed lawn, even a 'lawn' of grass mixed with some other non-grass forbs, so long as they can help with drainage and be cut with a lawnmower.

For an alternate solution, the part of my backyard that is entirely underneath the trees has been overgrown with English Ivy. This looks fine, and is actually easier to walk on than the slippery lawn, but doesn't meet my requirements of looking somewhat lawn-like.


Edit for more info:

enter image description here

This shows the general slope and transition from grass to ivy. The stuff under the leaves is mostly grass, though mostly dead.

Beyond the end of the slope there is about 50 yards of woods until the next house. There is a stream back here that is perhaps another 10 feet in elevation below my back fence; this picks up whatever runoff there is.

If you look at the neighbor's house/deck, the deck is attached to the main level and the basement opens into the backyard. My house is the same way, so all this yard is below my basement level, so there are no flooding issues. We are on city water and sewer which comes in through the front. My front driveway is probably ~20 feet elevation-wise above the fence at the back end of the property.

enter image description here

For reference, this is what a footprint looks like. It hasn't rained in about 72 hours, and there was a heavy rain about 90 hours ago. Note any footstep totally smashes the plants underneath, that's why no one in the family has been back here all summer, it just destroys what grass there is. Also note, there actually isn't much grass left. That footprint looks mostly like clover and wild strawberry.

  • 1
    Please send pictures that show the slope of the soil, location of your buildings, any drainage that you or the builder has installed. Forget plants that 'suck' up water to drain water. Let's look at your drainage problems first, what is causing this swamp. How are your basements? How are the properties of your neighbor's? Where are the city storm water systems? Do you have your own septic field or using city sewers? Let's figure out the problem without trying to use band aids, first. Plants will not cure your swamp. Drainage is kind of my specialty.... – stormy Nov 19 '18 at 4:30
  • 1
    @stormy More info added! – kingledion Nov 19 '18 at 18:47
  • 1
    Curious to read what @Stormy writes here - odd that the swampy area is uphill from a stream and woods. The only time I've seen standing water uphill is in a fen, which this is certainly not. At the risk of sounding stupid - Could there be a buried rock outcropping/spring under that yard? – Jurp Nov 20 '18 at 0:06
  • 1
    That slope 3' divided by 80' is less than 4 percent. Rise/Run=slope. I am almost thinking someone dumped fill on your backyard in an effort to flatten the slope. What Black Thumb said could be very pertinent here. If they did not compact that fill, THAT would be the reason for this wetness. When you said you dug the posts down 3 feet and never hit bedrock or some very tight clay layer tells me that they beefed up your back yard and few contractors know to compact the soil in layers. French drains are the answer for you. Those high tech drain pipe with their own fabric don't need gravel. – stormy Nov 23 '18 at 22:08
  • 1
    @stormy The previous back fence was pressure treated wood in concrete, and lasted about 15 years. It was pretty bad by the time I bought the house, so I re-did everything. I added extra gravel to the fencepost footings to try to extend the life of the posts, but if I can get 15 more years in that swamp, I'll count it a victory. There is air clearance on the bottom of the fence; but the bottoms tend to get moss covered even if they aren't touching the ground. I have pressure washed them once since installation to try to keep them clean. – kingledion Nov 23 '18 at 22:26
4

Most yards with this slope would drain better. It must rain an awful lot and your soil must be very high in clay. Nothing wrong with clay but this shows just how powerful water surface tension can be. Flat, electromagnetic tiny pieces of rock with little pore space and lots of rain will do this. I see lots of ranunculus in your lawn as well. I would assume a very low pH.

Installing a 'french drain' with herringbone tributaries, possibly 2 herringbone feeder lines into the central french drain might be enough to pull the surface water into the drain and away into a dry well?

You need to get that surface water being pulled out of the top 6 inches of soil. French drains will do that well. A central main vein and two, one on either side of this main line going from higher to lower and connecting to this central line/vein should cause that clay to give up its water, more quickly.

You have to have a dry well for all this water to be drained into; a hole 4'X4' and 3' deep, lined with l.s. fabric, filled with drain rock, covered with l.s. fabric and then covered with more rock or even duff from the forest.

The main french drain will day light into this hole. The angled collector lines will feed into the main line or 'vein'...think of a feather of a bird. The tip is uphill the quill is downhill. These french drains are easily dug using a 'trencher'. Easy to rent! If you had a viable lawn I would advise cutting the lawn and folding it back, trenching (16 to 18" deep), then laying drain pipe integrated with its own landscape fabric. Looks like 4 or more 3" PVC pipes, one on top of each other, covered with its own mesh and fits perfectly into this trench, no rock or anything else installed. Collects water and just the collecting of water PULLS more water from the soil and towards the main pipe which allows free fall of the water towards the dry well. The main vein/pipe can either be this high tech drain pipe or a solid pipe that takes the water to that dry well where is can slowly be absorbed into the ground.

Otherwise, you need to use 4" perforated drain pipe wrapped in landscape fabric that sits on a thin layer of pea gravel or just the soil itself. Usually the angled lateral pipes are perforated. The water then feeds into the main pipe which is usually not perforated and this causes positive drainage, just getting the water moving faster which pulls even more water out of the soil.

You also have a bit of work to do getting all that debris off the lawn. It stops the photosynthesis during the fall and it will also cause fungal diseases during the winter. Make sure you do not fertilize too close to winter time.

There are solutions for afterwards, but growing plants to suck up the water won't be one of them. Some ideas are to define a beautifully shaped small lawn...or two, where there is more light and make the rest of this area into beefed up plant beds.

Think of 'terracing'. You could also consider gravel. 3/4 minus crushed gravel. I love this stuff and when done correctly will be there forever. No soggy feet for sure. Terracing allows you to make interesting platforms, rooms, patios...out into your landscape. Low voltage lighting (not talking about those flying saucer path lights at all)...powerful.

First, like Kevinsky says! Drainage system in place first! Then let's landscape using your chunk of land's personality and make problems into some great design?

  • When I first moved into the house, I drew up some plans to cut that backyard into a three-tier terrace, and to install drainage. The highest tier would be grass, the middle tear have a patio-firepit area, and the bottom tier forest and ivy. I never got around to it, mostly because I've had three kids in the last 5 years. I guess you are telling me I should find those old drawings and get to work. – kingledion Nov 23 '18 at 22:32
  • Yay! Please send your ideas to us as a separate question! This is after all Gardening and LANDSCAPING! Perfect, a fire pit is contagious. Your neighbors will all want one! Look for a source (ha ha ha) for 3/4 minus crushed gravel. Look up Concrete Modular Units for walls. Dove gray with 30% darker grays, ASHLAR patterns, possibly double sided CMU wall units as well as 'Roman Cobble' 2"X7"X9" concrete pavers, tumbled. All walls will have a foundation and drain pipe. 4" of gravel over landscape fabric. 2X4 pt lumber as edging where necessary. Sq. Ft. / 81 = cubic yards for 4" depth. – stormy Nov 23 '18 at 22:45
  • Make dang sure you do not install a play area anywhere near that back fence, the closer the better. Keep your kids/pets close to the home and in sight at all times. You most certainly have cougar, bobcat and bear behind your fence...absolutely serious. Stalking, watching your patterns, hoping for puppies and cats. Keep them inside with cat boxes and the puppies/dogs always supervised. Cougars have nabbed kids walking right beside their parents in their own backyards. Just FYI. I dealt with this an awful lot, took people out to show them print, scat and hair proving their constant presence. – stormy Nov 23 '18 at 22:50
  • Well, I live about 20 miles from the White House, well within the confines of suburban Northern Virginia, so I strongly doubt I am going to see any cougars or black bear :) – kingledion Nov 24 '18 at 1:04
  • Dang! I wish I could take you out back to show you yes indeedy you live with these wild animals even within D.C. I worked in the Seattle area, quite the Urban and suburban confines and you bet there are these animals! I was on TV news with this subject! Lost 3 goats, Had to carry a news reporter on my BACK (5'2" and 120#)...those are MY stats! up to the back forty...oh yes, these animals are there and you will NEVER see them...honest. – stormy Nov 24 '18 at 3:52
2

For a lawn-like look (but one that may not require mowing), you should look into sedges (genus Carex). Here are some recommendations for your conditions:

Carex socialis

Carex rosea

Carex muskingumensis - Note that there are hybrids of this species that may be shorter than the species.

Most sedges (especially the more lawn-like ones) require dry or well-drained conditions, unfortunately. Note that sedges bloom like flowers, but their flowers are insignificant. You may find the seedheads objectionable, however, so it's a good idea to find photos of them if you're interested in planting a sedge.

The sedges I've listed may be best suited to your area covered with ivy rather than as a true lawn substitute.

  • 1
    yes, these plants will grow but to source them in quantities to cover a lawn area could cost a lot. Surely a drainage solution would be cheaper? – kevinsky Nov 19 '18 at 1:02
  • Depends on the area, of course, the amount of time that the landowner can wait, and nearby or mail-order nurseries. I've seen C. muskingumensis for sale at $6.00 (US) a 6" pot. Cheaper than sod, typically, for the same square footage. I could source other carex (C. appalachica, for example) at $4.00 a 4" pot. There are other inexpensive (and self-seeding) plant options (e.g. Caltha, Lobelia cardinalis, etc), but they're not grass-like. Now that I've seen photos, drainage offsite may be feasible. Also - the grass may be dead because it's bluegrass, not fescue/ryegrass (i.e. too much shade). – Jurp Nov 19 '18 at 23:59
  • Why not plant a few water loving trees? Willow/River Birch etc. – Dano0430 Jan 9 at 19:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.