A COUPLE OF YOU COMMENTED when I posted a spring “walk in the garden” photo gallery, asking for help with the subject of underplanting trees and shrubs (including my oldest magnolia, above). True confession: I have come very slowly and painfully to this lesson, dragged by some much more talented friends, Glenn Withey and Charles Price of Seattle. The lessons have involved some yelling, and even some tears (mine, not theirs). Still interested in learning how to “think mosaic,” as I now call underplanting?
My real education in underplanting began eight years ago, when (20-plus years into my gardening life) I learned the most important lesson of all: Ask for help, preferably early and often. So rather than remaining embarrassed that I wasn’t as confident in making complex and large mixtures of plants, despite all I knew about them individually, I asked Glenn and Charles to come and teach me.
Things got started really badly, and I feared for the friendship. The lowpoint was Day 1: I came around the corner of the house to find Charles (below, in full Pacific Northwest-style rain gear) holding my most treasured plant—in pieces. Without asking, he’d uprooted it and sliced it into tiny chunks. I shouted. He shouted right back. And so I cried, feeling out of control on so many levels.
Of course Charles had done exactly the right thing when the goal is underplanting large areas, such as beneath trees: You need more, more, more of a few key plants to make it all come together. He was making more of my Hylomecon japonicum. At that moment, I didn’t feel quite so philosophical about it, however.
Just this spring, Glenn and Charles, who curate the wonderful Dunn Gardens in Seattle and have a design business as well, visited again for two days. Being much bolder now and with years’ more practice, I uprooted precious things myself with abandon—trilliums and yes, the Hylomecon and goldenseal and other shade-loving treasures. Under two more big, old apples we replicated the successful pictures they’d taught me to create under my oldest magnolia (top) and oldest apple, (carpeted with hellebores and more, just above) that inspired some of you to ask “How’d you do that?”
10 TIPS FOR UNDERPLANTERS
1. No ring-around-the-rosey, thanks anyway. Rather than circling the dripline of trees or shrubs (or a group of trees and shrubs) with groundcovers and bulbs and such, you have to get all the way in there, even right up against the trunk (like this old apple’s above), to make it look UN-manmade…as if it just happened.
2. No polka-dots (except at first): Like I said, It’s all about learning to “think mosaic,” which doesn’t mean polkadots of onesies, but sweeps and drifts and deliberate repetition of said sweeps and drifts. At first, though (as above in a newly laid-out bed under an unseen smokebush in front of the house) no matter how many plants you buy or what you feed them, the new underplanting will look like hell (well, like polka-dots). Which leads to the next lesson:
3. Patience is required. (If you did not know that already, I suspect you have not started a single seed let alone planted a young tree.) This gardening nonsense is all about patience—frankly I think it’s a patience-building practice more than anything else. Your bed will look better next year, and almost great two years after planting. After the third or fourth year you can start harvesting divisions of some plants to repeat your success elsewhere.
4. Select a palette that relies on several key plants, with a few others as punctuation (the little gems to pop up from the carpet beneath them). Buy (or divide) so you have lots of each mainstay to get you started. The late-spring-to-fall palette under my oldest magnolia, top photo and above, is glossy European ginger, yellow Hakonechola macra ‘All Gold,’ Japanese painted ferns and Hosta ‘June,’ with a couple of young ‘Lime Rickey’ heucheras picking up the gold grass.
5. Include ephemerals, early spring bulbs or perennials that come and take advantage of the sunshine before the canopy leafs out, then vanish underground or at least don’t take up much space. Winter aconites, or trilliums, or hylomecon, or Dutchman’s breeches, or bloodroot, or Virginia bluebells…the list goes on. I get about six extra-early weeks of color from my underplantings, before my mainstay plants fill in, by using ephemerals lavishly. That’s the same bed (just above), in April-into-May.
6. Include some “groundcover” types, meaning plants that form thick mats (but not English ivy or pachysandra or vinca!). I am partial to epimediums, European ginger, Hackonechola macra ‘All Gold,’ hellebores, perennial geraniums of a semi-evergreen nature (like ‘Biokovo’ or macrorrhizum), among many.
7. Make space for some real gems. Gems might include species peonies, choice hostas like ‘June’ (a favorite of mine), or even bulbs, like an outburst of martagon lilies or primulas, like the orchid-pink P. kisoana (below, in that same magnolia bed but another two weeks into spring) for an unexpected moment.
8. When choosing plants, remember that leaves are your best friend. Plan on a mix of textures and colors, coming mostly from foliage (as the leaves will be there all season or even all year, and the flowers just come briefly). Think of the color range of heucheras alone you could employ, or hostas—foliage is hardly boring. Which relates to this lesson:
9. Texture is also a great ally. Work it. I cannot imagine “mosaics” working without some linear things (grasses like Hackonechloa, or sedges), contrasted against some ferny things (like, well, ferns) and against some large-textured things (like bigger hostas, or perhaps mayapple, or Diphylleia cymosa).
10. Once you’ve selected a palette, repeat, repeat, repeat. Not just in the first area you underplant, but (if it works) in another area in need of some extra interest, where it may be all mulch right now or a sea of a single groundcover. Soon your first mosaic will fill in and afford you some divisions, and on to making the next beautiful carpet you will go (maybe with help from a great teacher like Charles or Glenn, below, having at it under another apple). 
an update on underplanting trees and shrubs 
the toughest groundcovers i rely on 
touchy-feely plants 
Great article. I live in New England with lots of shade. You inspired me and educated me as to how to fill in those dark areas better!