Warfare in the garden

It may look rough, it may look bare, but this is the time of the year to see what's happening at soil level. It's easy to see which plants are competing with their neighbors, which plants may be getting the upper hand, where the problems are. Here is a sweeping view of the garden from the hydrangea "bower" (well, bower-in-progress) on the far side of the garden.

The area I'm headed for is the inside of the curve in the path, on the right side of the next photo.

Here ... though this may look a mess, gets to the heart of the kind of gardening I'm doing at Federal Twist. There isn't much open ground in my garden; I've planted to try to prevent that, using plants as a living mulch to limit undesirable self-seeding, to suppress weeds, to control how the garden grows and how the planted areas interact, to the extent that's possible.

But here I created a small piece of open ground--originally to raise the soil level so I could grow Eryngium yuccafolium (Rattlesnake master). I also wanted to try using Bergenia and a European bunch grass, Sesleria autumnalis, as groundcover. I can't say that was successful, not yet anyway, so I decided to see what I could do with seeding. I like the early umbelliferous flowers of Poison hemlock (Conium maculatum) that grows along the roadsides nearby so I collected seed and scattered it here. It's the plant with lacy, carrot-like foliage, in its third year now. (Yes, this is the same plant used to put Socrates to death, so it's of alien origin.) Then Ironweed started to self-seed. And thistles, and other interlopers.

Not wanting to replace this natural mechanism entirely, wipe it out and put in some plant combination that I know will dominate and rule the area (though that option remains open), I'm letting the self-seeding continue, but managing the process by weeding out plants I find pernicious or otherwise undesirable.

Unstable and subject to continuing change as this area is, it requires management throughout the growing season. The Poison hemlock, for example, grows rapidly and blossoms in June, then promptly dies and becomes a rather unattractive, brown skeleton. I cut and remove it, and let the later blooming Eryngium and Vernonia take over the space. I'll eventually want to find a stable condition, but don't yet know what that will be. The goal will be to cover the ground with only desirable plants.

So it goes on the larger scale, though the garden as a whole is much more stable because it's full of large, dominant plants. The apparent empty spaces around the red logs isn't empty at all. I've planted several clumps of Miscanthus giganteus to screen the view of the deer fence behind and to provide a visual boundary to the garden, as well as other kinds of miscanthus, and on this side, Panicum 'Dallas Blues' and Petasites japonicus for variety of texture and color, and for the practical purpose of covering ground.

Above are the early flower spikes of a hybrid Petasites I use massed in two large areas. Not much can compete successfully with Petasites. Below are the flowers of Petasites japonicus, similar to the hybrid, but with round rather than angular leaves.

These willows, Salix sachalinensis 'Sekko', through shading and root competition, also dominate their ground.

Some other plants seem to dwell undisturbed above the competitive fray, peacefully apart from a kind of warfare that exists at ground level. Lindera benzoin (Spice bush) is one such plant. It fills the woods around here, and now as you drive along the roads or walk, you see clouds of Lindera blossoming, almost like yellow flurries of snow.

It's another kind of actor, seemingly able to adapt successfully to just about any kind of competition. If you follow the rule that there are three kinds of plants--ruderals (pioneer plants that quickly cover bare ground), competitors, and stress tolerators--this must be a stress tolerator.

Here, the field of battle.

Garden Diary: Competitors, Stress Tolerators & Ruderals

Having worked for several years to establish a matrix of plants that will be at least partly self-sustaining, I can see some progress this spring. At this stage, I'm still keeping pretty much anything that covers the ground and prevents random germination from the seed bank.

Thanks to Noel Kingsbury's books, I now know I'm trying to orchestrate a bunch of competitive perennials, stress tolerators, and those opportunistic ruderals, plants that take advantage of any open ground in the early stages of a planting, where they thrive until extinguished by larger or more competitive neighbors.

The picture below is of one of several Filipendula rubra 'Venusta' that have settled in well and are slowly spreading. I'd judge these to be moderate competitors; they are slowly covering more ground, but they don't self-seed at all.

Next is another sample of a matrix planting, primarily Petasites hybridus, native Equisetum arvense, native Lysimachia nummularia, and at the far edge, Carex muskingumensis, Darmera peltata, cimicifuga (actea), and thalictrum. The equisetum, though highly invasive and a competitor par excellence, will wither away in a month or so, leaving room for a really disgusting ruderal, Japanese stilt grass (Microstegium vimineum), to intrude.

The vertical wands rising from the petasites are flowers, which you can see more clearly in the next photo.


The next two photos show views turning clockwise about 150 degrees.


The more "finished" matrix above contrasts markedly with another garden view below. Here is where the filipendula I opened with grows, along with other large wet prairie perennials such as Eupatorium purpureum (Joe Pye Weed), Liatris pyncnostachya, Rudbeckia maxima, assorted wetland irises, sanguisorbas, miscanthus, panicums, and other plants too numerous to list. Obviously there are no early perennials to make an attractive matrix planting here. This area won't reach its potential until July.


Here is where I need to develop spring plantings that will give interest and good coverage early in the season, then disappear, or at least tolerate shade cast by the larger perennials later in the season (spreading stress tolerators is what I need). More bulbs (stress tolerators) can certainly help, especially daffodils. Native persicarias especially like this area as the season progresses, so some early persicarias, such as Persicaria bistorta 'Superba', may be helpful. And, of course, a blanket of astilbes would give both color and interesting, long-lasting structure.

I'm open to suggestions.

Garden Diary: Speaking of Groundcovers

The experiment continues in the main garden - the wet prairie behind the house. Now that our cedar forest has become an open clearing, the light and air is changing the habitat that existed before. Though it makes for a rather messy look in spring and early summer, I'm leaving the established plant colonies such as bracken, sensitive fern, cinquefoil, violets, and equisetum to do their thing. In the newly opened spaces, ruderals (pioneer plants) have seeded in, and I'm leaving them too. I expect many of them to be here for several years until the more competitive species take over. With the passing years, and some judicious weeding to control such undesirable behavior as seeding into the crowns of established plants, I hope the natural process of plant succession and competition will result in the groundcover layer simplifying itself over time.

Here are some pictures of what's happening right now. First, a blanket of equisetum punctuated by a native Scirpus.


Though the equisetum is highly invasive, I like its soft, fuzzy effect seen from a distance, and its primitive character close up. I may as well; I couldn't get rid of it without some highly destructive intervention. And the Scirpus grows so large, and so profusely, it also behaves as a groundcover though on a much larger scale.

In wetter areas, sensitive fern, another "legacy" plant, slowly spreads. I guess it would be classified as a stress tolerator. It lives in very wet places where most other plants would languish. You can even see some pooled water here from a recent rain. Not an example of well drained soil!


Bracken and cinquefoil have covered this corner with two levels.


I know bracken has a reputation for being a real thug, but in my garden environment it is rather well behaved. And it's such an attractive structural plant I'd be happy to have more. In front of it is a carpet of cinquefoil in bloom. Not a beautiful plant, unless closely examined, but useful for covering large areas quickly.

Plants I want to suppress are multiflora rose and poison ivy (Toxicodendron radicans). They have no desirable qualities, in my view, and seem able to compete with just about anything in the plant kingdom, so I'm driven to digging and using Roundup in my struggle with these invaders.

Most of the large prairie-type plants I've inserted into the groundcover matrix - Eupatorium purpureum, Filipendula rubra 'Venusta', Liatris pycnostachya, Rudbeckia maxima, various Silphiums, and large grasses - have no trouble penetrating this dense cover. By midsummer, they'll begin to dominate the landscape and the less attractive lower level will disappear into the background.