Interior West: Full Pockets

BY LAUREN SPRINGER / Masonville, Colorado, Zone 5

PLANTS between dry-laid paving stones are nothing new in European gardens. Nature takes her cue, and presto—the romantic, tufty, fuzzy walkways of “neglected” gardens. In England, a few bricks are pulled from a courtyard or path and a plant popped in; they call this crazy paving. Here in the United States, flagstone interplanting beyond thyme and chamomile is still the domain of only the most fanatical gardeners. In most American gardens, the harsh plane of patio and path remains unbroken.

That ought to change, and not just for the sake of aesthetics. Where wildfires are a concern, stone is a common-sense firebreak. For water conservation, planting between stones is a form of mulching. And in areas with short growing seasons and large temperature fluctuations, stone protects roots, cooling them in the shade, warming them in the sun, creating microclimates for less hardy plants, as well as extending the season.

Ruddy local sandstone encircles my house—more tons than I care to remember. Varying pockets of two to five inches between stones makes for easier masonry as well as new gardening space. On the sunny, calm, south side, plants between the stones stay green long into winter and bulbs begin blooming in January, while elsewhere in the garden the same species are worn and withered by New Year's and the bulbs nowhere to be seen until March. Here the ground rarely becomes saturated or deeply frozen, so the stones are laid directly on the native clay. Thriving in the cooler, moister shade of the northeast patio are saxifrages, dwarf coralbells, petite sedges, and others that would not survive elsewhere in the garden. There is frost heaving on this side, so we mixed sand and manure with the soil before setting the stones.

For those who love rock garden plants but not the look of most rock gardens, flagstone gardening is a great way to grow these small, often evergreen plants that like the well-drained, cool root run afforded by a nearby stone. I tuck many a so-called fancy rock garden plant between flagstones—Eriogonum porteri, E. cespitosum, E. ovalifolium, Artemisia caucasica, Globularia species, dwarf hypericums and dianthus, drabas, miniature sempervivums, and rosularias.

In all but the most traveled areas, tufts of plants punctuate the low-growing crack-fillers. Festuca glauca 'Sea Urchin’, Aristida purpurea, erodiums, and small penstemons break up the flatness of delospermas, veronicas, and pussytoes. This is a fine balancing act—too many larger plants and the stones become a jungle, difficult to walk on, with lots of trampled foliage and overgrown, choked-looking plants. My rule of thumb is to put one tussock plant every four to nine square feet. Nature also plants her own seedlings between the stones, and they are far healthier than any plants I've shoehorned in over the past five years. They allow me to follow their lead as to what grows best, and give me the pleasure of editing, in the gently controlled chaos that is gardening.

Pineleaf penstemon

Penstemon pinifolius

This southwestern native is more adaptable and long lived than most penstemons. Grown in any well-drained soil, it forms a heathlike mound. The profuse, tubular, yellow (‘Mersea Yellow’ and ‘Magdalena Sunshine’) to orange ('Shades of Mango’) or red flowers attract hummingbirds; deadhead once finished. Give the plant full sun or very light shade, and little if any extra water. Hardy in USDA Zones 4-9.