Garden Notes

Thank you, Polly Hill

Narcissus 'Actaea'
Narcissus 'Actaea.' Photo by Susan Safford

By Abigail Higgins - May 10, 2007

Although two weeks later than usual, the narcissus show has been worth the wait this year. These are Narcissus 'Actaea,' a mid-season cultivar that resembles the later-blooming pheasant's eye, N. poeticus. Strongly scented with a blizzard-white perianth, N. 'Actaea' is a classic.

Thinking of Polly Hill and the many exceptional and now-mature trees she patiently grew raises our consciousness about trees. It is urgent, now that it is the spring landscaping season, to remind homeowners and landscapers to avoid tree abuse on the property.

Most trees do not naturally grow in grassland, but create their own micro-environment through the litter of their leaves and twigs, which are broken down by soil micro-fauna adapted to the job by their own dietary needs. Grasses and trees have different requirements in terms of their ideal soil micro fauna. Grasses want a higher balance of bacteria to fungi and trees want more fungi than bacteria.

The look of trees growing in greensward is a pretty picture. Smooth lawn right up to the trunk is not ideal for the tree, however. It is good and beneficial to mulch trees and shrubs: the mulch layer replicates the environment of their own litter. What is counter-productive is piling the mulch around the trunk in cone-shaped mounds - called "mulch volcanoes" by some tree experts.

construction site
Construction abuse: the shattered limb lies under the victim on a job site.

In fact, this practice is an invitation to tree failure through suffocation and rot. The trunk and its bark need to breathe. The piled-up mulch is a medium for insects, rot organisms, and provides cover for gnawing rodents. It may promote girdling roots and strangling. Instead, please try mulching to an even depth of two to three inches, kept well away from the root flare, extending out to the drip line.

When it comes time for house renovation or repair, a few steps taken on behalf of trees growing on-site can prevent damage and ensure their continuing health. If you are on an in-town lot every established tree is irreplaceable. The soil level around the tree - the line of soil on the trunk flare at which the tree has been growing - should not change.

Avoid re-grading around existing trees. If a change is unavoidable, build a well around the trunk. Protective fencing helps to keep trees out of the danger zone. Tell the contractor that the condition of the trees when the job is finished will determine whether he receives payment in full. Arranging hay bales around the root zones helps control erosion and shifting of soil.

Soil compaction and root breakage are two kinds of tree damage that are invisible or overlooked but are harmful just the same. The shallow roots of trees like maples and pines are more sensitive to soil compaction from machinery and construction than are the deeper, straight-down root systems of trees like oaks.

Tie off the limbs and branches near to structures or where machinery needs to operate. (Tying it off might have prevented breaking this tree's large limb, see photo.) Put down plywood, terra mats, or landscape cloth covered by a cushion of wood chips to protect root zones. Sometimes tree damage is unavoidable, but a little forethought can spare you the unsightly decline of trees or the expense of their removal after suffering from construction abuse.

Fir tree
The trunk of this fir is buried in mulch and needs to breathe.

Remembering Polly Hill

Many of us practice a kind of simple gardening, even those among us with spectacular gardens laid out in the best of taste. What one learns to see from a Polly Hill, or what sets a gardener of her sensibility and skill apart from the rest of us, is breadth and discernment. Between them these qualities create complexity. The rest of us are doing nothing wrong: it is only that conventional notions and masses of colorful flowers are not the only forms a garden may take.

Of the many pithy quips, plant introductions, garden lore and pleasurable moments connected with Polly and her husband, Julian Hill, two are significant for me. Gardeners will be reassured to know that, while starting as a chemically assisted gardener (she was the spouse of an illustrious chemist, it must be remembered) Polly eventually abandoned her DuPont arsenal in favor of organic principles. Composting, mulching, and wire cages became her modus operandi; even watering is done only to get plants established. "If they're going to be suitable for the Vineyard, they have to be able to make it on their own" was the crisp judgment she passed upon her plants, some of them having spent years in germination and infancy.

The second significant quality is of course Polly's quixotic starting to plant and grow the collection at age 50, the midpoint then of what would become a lifespan of 100 years. When we lived at the Homestead and I would make the rounds with Polly in the golf cart, she'd gesture left and right: "I don't know why I'm growing this stuff, I'll never live to see any of it mature...." The inspirational message is clear: do it.

Many neophytes and rank beginners, as well as horticultural notables, have found their way to Barnard's Inn Farm and, later, to the Polly Hill Arboretum. I believe each who arrived prepared to learn or to talk "serious plant talk" received a gracious and attentive welcome from the slight woman with snapping blue eyes and snow white hair whose acres and plants comprised her great domain.

No less conventional or limited than the rest of the ordinary gardening world, I do avoid making mulch volcanoes. What was my good fortune was to be thrown in contact with Polly Hill, who was most kind and forbearing with my uninformed, juvenile enthusiasms. Conventions and hoped-for masses of color continue to be the aim of most of my labors, but, thanks to her, I really do see more and more, and most importantly, realize I know less and less.