Native plants for finicky soil conditions - Ask Extension
Hello.
I am interested in helping wildlife by growing native plants, but my back yard has very finicky conditions, and everything I plant dies. (I ha...
Knowledgebase
Native plants for finicky soil conditions #890432
Asked December 02, 2024, 1:07 PM EST
Hello.
I am interested in helping wildlife by growing native plants, but my back yard has very finicky conditions, and everything I plant dies. (I have no problem in the front hard). Could you advise me on what native plants might grow in shady, heavy clay soil that is on a slope? Currently the invasives are the only things thriving. I’ve attached a few pics (apologies that the dog insisted on photo-bombing them all) Thank you!
Prince George's County Maryland
Expert Response
We're happy to share some ideas, but having a bit more information would help us to narrow-down some options.
Does the soil skew dry due to root competition from the trees, or does it skew damp from being downslope of the rest of the yard? (Does a roof downspout outlet empty in that direction?) Granted, this summer and fall we've experienced a notable drought (which hasn't abated yet), but if you have experience from prior years with the site, maybe that's a better indication of average wetness or dryness.
Do deer browse in the yard? (They can jump over many garden fence heights, but the presence of the dog might be discouragement enough.)
Is there a maximum size (height/width) for any shrubs you may want to use? Or would you prefer to stick to herbaceous perennials (those dying back to the ground in winter)?
Which plant species have failed in that area thus far? Knowing which plants died out from prior planting attempts might help us to determine what the biggest challenge of the growing conditions might be. Conversely, some plants are much more sensitive to growing conditions (or more vulnerable to commonplace infections or pests), so their loss might not point to an issue with the site so much as them not being the most resilient option in any setting.
Miri
Does the soil skew dry due to root competition from the trees, or does it skew damp from being downslope of the rest of the yard? (Does a roof downspout outlet empty in that direction?) Granted, this summer and fall we've experienced a notable drought (which hasn't abated yet), but if you have experience from prior years with the site, maybe that's a better indication of average wetness or dryness.
Do deer browse in the yard? (They can jump over many garden fence heights, but the presence of the dog might be discouragement enough.)
Is there a maximum size (height/width) for any shrubs you may want to use? Or would you prefer to stick to herbaceous perennials (those dying back to the ground in winter)?
Which plant species have failed in that area thus far? Knowing which plants died out from prior planting attempts might help us to determine what the biggest challenge of the growing conditions might be. Conversely, some plants are much more sensitive to growing conditions (or more vulnerable to commonplace infections or pests), so their loss might not point to an issue with the site so much as them not being the most resilient option in any setting.
Miri
Thanks so much!
The soil generally skews dry (I think due to the slope and tree roots). But when I've tried to dig a hole to plant something, the roots rot due to the poor drainage.
We have no problems with deer, though plenty of ground hogs, squirrels, and racoons.
I have no minimum or maximum size limits.
I have tried a variety of plants--both non-natives and natives--in both seed and seedling form. Here is a list of some that have failed:
Seed (I think they just washed away due to the slope and rain):
-Garlic chives
-Milkweed
-Black eyed susans
-Crimson clover (attempted cover crop to improve soil)
-White clover
-Buckwheat (attempted cover crop)
-Daikon radish (attempted cover crop)
-Every variety of grass seed imaginable, including "patch" mixes that have fertilizer
-Alpine strawberry
-Goldenrod
Saplings/live plants (I think some of them had root rot due to the clay soil, but I'm not sure):
-Andromeda
-Inkberry
-Virginia pine
-Juniper
-Red and pin oak trees (these were 20–30-year-old trees that died last year. We don't know why, but we lost 4)
-Ferns
-Japanese maple
-Mountain laurel
Bulbs (maybe squirrels dug up?):
-Allium mix
-Gladiolas
-"Blazing stars"
Here are things that are doing OK:
-Wild persimmon
-Every invasive imaginable (English ivy, honeysuckle, porcelain berry, periwinkle).
-Poison ivy is also doing great
-Virginia creeper
-Holly (which I love, but I have kids and don't want a ton more poky leaves)
-Azalea
-Remaining oak trees
-Wild black cherry trees
Thank you so much for your help!
Meadow
Thank you for the additional information, that is helpful. We'll include some links to helpful pages, though we don't have a profile page for each of the species mentioned below.
As for the seed list, the species listed prefer full sun (or at least more direct sun than shade in summer), and poor germination could definitely have resulted from soil moisture fluctuations (germinating seed, both flowers and turf, cannot dry out for long) and possibly being eroded downhill, as you noted. Many of the other species listed are also sun-loving, so might struggle if growing in too much shade.
The declining/dying oaks were probably not a casualty of soil type, at least not anything acute. Chronic stress or cumulative stress/damage can result in tree decline, and a wide variety of factors can contribute to the loss of a tree, which sometimes begins years or even decades before it snowballs into rapid or dramatic dieback. Our What Causes Trees and Shrubs to Die? page provides more information if you're curious. Although the lost oaks aren't necessarily a threat to the health of the remaining oaks, if there is a common stressor affecting all of them, you can always have the trees evaluated by a certified arborist or licensed tree expert. They can't always treat or cure every condition, but can assess any existing damage and look for sources of tree stress that might be able to be alleviated.
Some plant species are more vulnerable to root rot than others. Clay soil alone isn't necessarily a problem, though it can impede drainage when compacted (walked on often) and species requiring excellent drainage might not fare well in a clay-heavy soil. Andromeda (Pieris species) and Mountain-Laurel (Kalmia latifolia) are two examples. Interestingly, their cousin, Azaleas, are also sensitive to staying too wet and growing in compacted soil, so unless the plants are older and more established, perhaps where they are located, drainage is a bit better.
Ferns are a very diverse group. While most thrive in a mix of sun and shade, or handle a mostly-shady exposure well, some prefer more evenly moist soil while others prefer to stay drier. If some ferns failed for you, there's no reason not to try again, as they are a great candidate for this setting. Christmas Fern (Polystichum acrostichoides) is a native species that stays somewhat evergreen and handles "dry shade" among tree roots well, and both Sensitive Fern (Onoclea sensibilis) and Hayscented Fern (Sitobolium punctilobulum, formerly named Dennstaedtia punctilobula) are both aggressive native spreaders that can help to colonize an area needing erosion control.
Below are some ideas for native perennials and shrubs that either prefer or tolerate a mostly-shaded exposure with soil that might skew dry or damp (if clay is compacted, it will drain more slowly after rain or irrigation). It's not an exhaustive list, but may provide some inspiration. When planting amid tree roots, try to install the youngest (smallest pot size) plant size possible, as that will require the smallest planting hole, so you don't have to wrestle with tree roots in the way as much. This is especially helpful for shrubs, since the hole dug for root balls should ideally be at least 2-3 times as wide as the root ball's size in the pot. A shrub pot size considered small would be around a 1 gallon pot; often, they're sold in 2, 3, or 5 gallon pots, as a point of comparison. Most perennials are sold in 1 or 2 gallon pot sizes, but quarts are younger plants that might be easier to establish and will cost less.
Avoid installing seedlings or seed unless you can germinate them somewhere else more protected first (and in a potting mix that drains better), where they can be transplanted into the garden after a few months or a year of growth. Plus, germinating seed in pots versus directly in the ground makes weeding the plants and determining which seedlings are the desirable plants and which are not much simpler. Often, seedling plants (both of desirable species and of weeds) look quite different than the mature plant, making ID harder. A middle-ground may be the use of "plugs," which are plants older than seedlings but younger than most nursery potted plants. Usually, plug options will be perennials, but occasionally might include shrubs. Native plant specialty nurseries are more likely to stock plugs than a more mainstream garden center, but overall, plugs are increasing in popularity for their inexpensive and easy-to-plant size. They will be further from flowering age than older nursery plants, but catch up in growth faster than we'd expect.
Between blooms or berry-ripening season, visual interest can be created in the shade garden by use of differing growth habits and foliage colors/textures. Upright grassy leaves, for instance, like those of sedge or River Oats (Chasmanthium latifolium) can contrast nicely with fern fronds or the flatter, wider leaves of Ragwort or Wild Ginger (Asarum canadense). Cultivars with more blue-toned, golden, or white-marked leaves can also add color when blooms are lacking. Wildlife value comes from not only flowers but berries or seed heads, foliage (like for caterpillars), and shelter from the weather or predators. Growing a diversity of plants also helps to attract a diversity of insects, which in turn supports birds and other animals.
Miri
As for the seed list, the species listed prefer full sun (or at least more direct sun than shade in summer), and poor germination could definitely have resulted from soil moisture fluctuations (germinating seed, both flowers and turf, cannot dry out for long) and possibly being eroded downhill, as you noted. Many of the other species listed are also sun-loving, so might struggle if growing in too much shade.
The declining/dying oaks were probably not a casualty of soil type, at least not anything acute. Chronic stress or cumulative stress/damage can result in tree decline, and a wide variety of factors can contribute to the loss of a tree, which sometimes begins years or even decades before it snowballs into rapid or dramatic dieback. Our What Causes Trees and Shrubs to Die? page provides more information if you're curious. Although the lost oaks aren't necessarily a threat to the health of the remaining oaks, if there is a common stressor affecting all of them, you can always have the trees evaluated by a certified arborist or licensed tree expert. They can't always treat or cure every condition, but can assess any existing damage and look for sources of tree stress that might be able to be alleviated.
Some plant species are more vulnerable to root rot than others. Clay soil alone isn't necessarily a problem, though it can impede drainage when compacted (walked on often) and species requiring excellent drainage might not fare well in a clay-heavy soil. Andromeda (Pieris species) and Mountain-Laurel (Kalmia latifolia) are two examples. Interestingly, their cousin, Azaleas, are also sensitive to staying too wet and growing in compacted soil, so unless the plants are older and more established, perhaps where they are located, drainage is a bit better.
Ferns are a very diverse group. While most thrive in a mix of sun and shade, or handle a mostly-shady exposure well, some prefer more evenly moist soil while others prefer to stay drier. If some ferns failed for you, there's no reason not to try again, as they are a great candidate for this setting. Christmas Fern (Polystichum acrostichoides) is a native species that stays somewhat evergreen and handles "dry shade" among tree roots well, and both Sensitive Fern (Onoclea sensibilis) and Hayscented Fern (Sitobolium punctilobulum, formerly named Dennstaedtia punctilobula) are both aggressive native spreaders that can help to colonize an area needing erosion control.
Below are some ideas for native perennials and shrubs that either prefer or tolerate a mostly-shaded exposure with soil that might skew dry or damp (if clay is compacted, it will drain more slowly after rain or irrigation). It's not an exhaustive list, but may provide some inspiration. When planting amid tree roots, try to install the youngest (smallest pot size) plant size possible, as that will require the smallest planting hole, so you don't have to wrestle with tree roots in the way as much. This is especially helpful for shrubs, since the hole dug for root balls should ideally be at least 2-3 times as wide as the root ball's size in the pot. A shrub pot size considered small would be around a 1 gallon pot; often, they're sold in 2, 3, or 5 gallon pots, as a point of comparison. Most perennials are sold in 1 or 2 gallon pot sizes, but quarts are younger plants that might be easier to establish and will cost less.
Avoid installing seedlings or seed unless you can germinate them somewhere else more protected first (and in a potting mix that drains better), where they can be transplanted into the garden after a few months or a year of growth. Plus, germinating seed in pots versus directly in the ground makes weeding the plants and determining which seedlings are the desirable plants and which are not much simpler. Often, seedling plants (both of desirable species and of weeds) look quite different than the mature plant, making ID harder. A middle-ground may be the use of "plugs," which are plants older than seedlings but younger than most nursery potted plants. Usually, plug options will be perennials, but occasionally might include shrubs. Native plant specialty nurseries are more likely to stock plugs than a more mainstream garden center, but overall, plugs are increasing in popularity for their inexpensive and easy-to-plant size. They will be further from flowering age than older nursery plants, but catch up in growth faster than we'd expect.
- Witherod Viburnum (Viburnum nudum), Arrowwood Viburnum (Viburnum dentatum), and Blackhaw Viburnum (Viburnum prunifolium)
- all handle a range of full sun to mostly shade (more flowers and berries if they get at least a little direct sun, though), and most will need cross-pollination in order to fruit (berry clusters), so for compatibility, choose a pollination partner that is the same species but a different cultivar (if you use cultivars); flowers attract pollinators and berries attract birds, and they have nice fall foliage color
- Winterberry Holly (Ilex verticillata)
- this is a deciduous (not evergreen) holly whose leaves are spineless; in order to get berries, plant at least one male winterberry for every 4-6 female winterberries; cultivars will be sexed, but if you use the straight species, it may be pot-luck which sex you get since they have to have the flowers examined when in bloom for nurseries to know which is which; bees pollinate the flowers and birds enjoy the berries, though not until late winter, so they can remain showy for some time after ripening
- Spicebush (Lindera benzoin)
- fragrant foliage (when crushed) and small yellow blooms in early spring; male and female flowers are on separate plants so pollination is needed, and often nursery plants are unsexed (it's hard to tell them apart), so planting several is probably the way to ensure fruiting; birds enjoy the berries on female plants, and Spicebush Swallowtail butterflies use the foliage as caterpillar food; this is a very common woodland understory shrub
- Common Witchhazel (Hamamelis virginiana)
- common, large-statured understory shrub; blooms around Oct-Nov, as its leaves turn yellow, so while the blooms are lightly fragrant, they are not as prominently showy as the non-native spring-blooming witchhazel species; handles drier soils well; good for end-of-season pollinators
- Black Huckleberry (Gaylussacia baccata)
- blueberry cousin that can form a spreading, low clump of growth; birds enjoy the berries, which are also edible
- Smooth Hydrangea (Hydrangea arborescens)
- look for either the plain species or a cultivar with wild-type flowers (that is, not the "mophead" ball of petals) for best pollinator value
- Golden Ragwort (Packera aurea)
- can spread aggressively, a good trait where a groundcover is needed to reduce erosion; supports pollinators
- Blue Wood Aster (Symphyotrichum cordifolium) and White Wood Aster (Eurybia divaricata)
- supports pollinators
- several species of Sedges (Carex)
- while some on the market are non-native (especially those with striped variegation), there are many locally native species, including some with fine, flowing green leaves or thicker blue-green leaves (example: Carex laxiculmis 'Bunny Blue') that clump but which can self-sow into colonies
- Great Blue Lobelia (Lobelia siphilitica) for areas that skew damp -- supports pollinators, including hummingbirds
Between blooms or berry-ripening season, visual interest can be created in the shade garden by use of differing growth habits and foliage colors/textures. Upright grassy leaves, for instance, like those of sedge or River Oats (Chasmanthium latifolium) can contrast nicely with fern fronds or the flatter, wider leaves of Ragwort or Wild Ginger (Asarum canadense). Cultivars with more blue-toned, golden, or white-marked leaves can also add color when blooms are lacking. Wildlife value comes from not only flowers but berries or seed heads, foliage (like for caterpillars), and shelter from the weather or predators. Growing a diversity of plants also helps to attract a diversity of insects, which in turn supports birds and other animals.
Miri
Thank you so much!
Wow! This is so incredibly helpful. I am going to do a deep dive on your email and links, but I wanted to thank you right away!
I am so glad I emailed! I really, really appreciate your thoughtful and detailed response. I’m excited to keep trying with the plants and techniques you mentioned.
Thanks again!
Meadow
You're welcome!
Sometimes it's just a matter of retrying plants, either in new locations, or even the same location, since occasionally it's the plant's health at the start of the project that predisposes it to decline (say, if roots were poor to begin with), or quirky weather stresses, rather than the location being unfit for a certain plant. And if a plant fails repeatedly in one spot, try another...sometimes soil drainage and other traits vary by just enough that one spot in a garden can be successful while another won't, even if it looks about even to our eyes. Buried debris we can't see, root competition, soil type changes (such as from fill when a house was built), and other unseen complications can all make it a puzzle sometimes to find the right spot for certain plants.
Good luck!
Miri
Sometimes it's just a matter of retrying plants, either in new locations, or even the same location, since occasionally it's the plant's health at the start of the project that predisposes it to decline (say, if roots were poor to begin with), or quirky weather stresses, rather than the location being unfit for a certain plant. And if a plant fails repeatedly in one spot, try another...sometimes soil drainage and other traits vary by just enough that one spot in a garden can be successful while another won't, even if it looks about even to our eyes. Buried debris we can't see, root competition, soil type changes (such as from fill when a house was built), and other unseen complications can all make it a puzzle sometimes to find the right spot for certain plants.
Good luck!
Miri