The clay dichotomy - when soils with high clay content become wet the become almost moldable, where as on the other end of the spectrum they form large, rock hard macro clods.
Over my few limited years of gardening there is a certain common phrase I've grown to hate.... "average, well drained soil." This seems to be what 90% of the popular garden plants available seem to require, yet it is the furthest thing away from the soils I've had the "pleasure" of gardening in. When I first started buying plants I was painfully oblivious that in most cases clay is a very, VERY dirty word when it comes to soil (get it, dirty... soil?, sooo clever) and means certain doom for many of the the beauties that I drooled over in plant cataolgues (Stewartia, Rhododendron, Kalmia, Cladrastis, Caryopteris, Agastache, Nepeta, Penstemon, Bearded Iris, Salvia, Heuchera, and the list goes on and on and on...). I've gradually come to accept my fate... after years of ripping out sad suffocating vestiges of what I thought would become vigorous, beautiful specimens.
Despite the impression I might be giving the problem with clay soils (or in my case pretty much just clay) is not fertility, but rather a size problem. Yes, a SIZE problem (insert joke here). The particles are so small and so tightly packed that there is virtually no room for air pockets, which means no oxygen for roots. To make matters worse any amount of disturbance (for example foot traffic from well meaning weeders) usually only compounds the problem and if you add in some occasional vehicular activity when the soil is wet and compaction may get to the point where the soil simply becomes too dense for roots too penetrate (another reason why I hate big clunky mowers). Clay soils also have an interesting dichotomy (particularly here in the east) where they go from being nearly completely saturated with water for 3/4 of the year (again depleting whatever small amounts of available oxygen there might be) to almost hydrophobic during the hotter drier months of the summer. The Missouri Botanic Garden has on excellent primer on clay soils as well as a few short lists of plants that can grow in them, but the long and short of it is clay soils make most garden plants sad. Very sad.
While I'd like to say that I've gotten to the point where I'm totally accepting of my native clayey soils, I'm not there quite yet. The plants that tend to gravitate towards clay tend to be, to put it mildly, a rather coarse, overbearing, and exuberant bunch, and by the time mid-summer rolls around, when left to their own devices, can form a riotous mess of plants both lanky and disheveled (I might be over-generalizing just a bit.... and as a general disclaimer my view point may be slightly tainted by years of being bombarded with images of scrumptious plants that I will never be able to grow). I was reminded all to well of this clay induced rambunctiousness after considering it in contrast to a winter trip to the back dunes of Cape Cod (this was before much of eastern mass was under several feet of snow). There is something about the sterile sandy soils of the cape that demands a decidedly austere simplicity of the plants that prefer it.
Pitch Pine (Pinus rigida) along with Scrub Oak (Quercus ilicifolia), not pictured, form the dominant woody vegetation in the back dunes of Cape Cod. Here, C. pennsylvanica blends with the fallen pine needles to form a spongy carpet
Pinus rigida - Pitch Pine
Zone: 4-7
Purchase from: New England Wetland Plants, Edge of the Woods Native Plant Nursery, American Native Nursery, ArcheWild Native Nurseries
Carex pennsylvanica - Pennsylvania Sedge, Oak Sedge
Zone: 4-7, although I've seen plenty of 3-8
Purchase from: Classy Groundcovers, Everwilde Farms, Greenwood Nursery, Morning Sky Greenery, Prairie Nursery, Prairie Moon Nursery, Santa Rosa Gardens, Shooting Star Nursery, Yellow Springs Farm
The sterile soils of the back dunes cause F. grandifolia to grow to probably only 2/3 the height of what you would normally find in more nutrient rich habitats further inland. SIDE NOTE - If I ever happen to catch one of you idiots who feels the urge to carve into the trunks of these beautiful trees, RUN, because I will come after you!!!
Fagus grandifolia - American Beech
Zone: 3-9
Purchase from: Nearly Native Nursery, Cold Stream Farm, Forest Farm, Heritage Seedlings, Mail Order Natives
Dicranum ?scoparium? - Rock Cap Moss
Zone: no bleepin idea...
Purchase from: Moss Acres
Probably not the best photo of I. glabra (it's the only green plant material in this picture), but up to this point I had never seen this ubiquitous evergreen landscape shrub in its natural habitat.
Ilex glabra - Inkberry
Zone: 4-9
Purchase from: (Lots of different cultivars available from lots of different places, but if you look you can find straight species from a few places) Nearly Native Nursery, Yellow Springs Farm, New England Wetland Plants
When I've come across G. procumbens growing in more woodland-ish (humus rich) soils under the the shade of much larger trees further inland its always been fairly sporadic and patchy. Here in the sandy soils of the Cape with a bit more sun it grows as a luxuriant and continuous groundcover that could even give Pachysandra a run for its money. Many native ericaceous plants, like legumes, have very strong mycorrhizal relationships that allow them to grow vigorously in soils of very limited fertility. Sometimes fertility can actually impede the growth of such plants.
Gaultheria procumbens - Wintergreen, Eastern Teaberry
Zone: 3-8
Purchase from: Accents for Home and Garden, American Meadows, Forest Farm, Garden in the Wood of Grassy Creek, Lazy S'S Farm, Romence Gardens, Sooner Plant Farm, Heritage Seedlings
When the soil profile of this area was exposed it was easy to see that organic matter made only a small thin veneer over a monolithic layer of almost pure sand below.
You may be asking yourself why I'm showing images of sand loving plants when I'm talking about clay soils. If nothing else, seeing this compelling landscape in person (granted for the most part undisturbed by people) brought home the fact that soils come first, then the plants, not the other way around. It may be hard to resist the seductive hybrids and cultivars that the horticultural industry peddles incessantly, but if you ever hope to have a landscape that is at at the very least some what self-sustaining, do your due diligence. Get outside in your yard and dig around a bit, hell, go and get your soil tested. I mean you could always try it my way or you could avoid the years of soil amending, wasted money, plant heartbreak, and residual horticultural bitterness and simply accept the hand you were dealt. I suggest the latter.
