A ground cover that keeps giving

I planted a Black Lace in a barrel earlier this year and the soil around the stem was sitting bare, which bothers me. Exposed compost in a container does two things and neither is good: it dries out fast and it grows weeds.

The original plants came from the parents of an old classmate of mine, back in my hometown, years ago now. A handful of plants, handed over the way people hand over plants. Planted in my cabin garden, they did what smultron does, and now there's more of it than anyone planned for. Taking a crateful out barely registered.

That's the thing about giving away a plant that multiplies. You're not giving someone one plant, you're giving them every plant they'll ever get from it and everything they'll pass on afterwards. It costs nothing. It spreads sideways through people the same way it spreads through soil. And what it spreads is fairly specific: something sweet in July, a bit of whimsy in a corner that would otherwise be bare, and a reason to crouch down and pick, which is really a reason to stop moving for a little while.

I've handed plants from this same stock on to two other people. The parents of a boy I went to school with are still, in a sense, planting things in my garden.

The plant

Parksmultron is Fragaria moschata, ‘Askungen’, Musk strawberry in English, hautbois in French. It was the standard garden strawberry across much of Germany until the modern jordgubbe pushed it out in the 1800s, and it's been grown in Sweden since the 1600s. Bigger berry than skogssmultron, smaller than a jordgubbe. The taste is the reason anyone still bothers — strawberry with something like raspberry and pineapple sitting behind it.

It spreads by runners, which is the whole point for this job. I don't want to plant this gap again next spring. I want it to close on its own.

They went in already in flower, which is not how you're meant to do it. You're supposed to let them settle first. But the crate had been sitting on the brick for over a week getting drier by the day, so in they went. Small white flowers, five petals, yellow middle, held low enough that you'd walk straight past them.

The elder is Sambucus nigra 'Eva' — Black Lace. That pairing is the reason I chose smultron and not something evergreen and dutiful.

Black Lace is close to black and so finely dissected that from any distance it stops reading as leaves and turns into texture. Eventually it's a heavy plant, visually. For a couple of weeks in early summer it puts out flat umbels of creamy pink flowers that sit right against the dark foliage, and that pink is the only warm thing anywhere on the shrub. Then it's gone and you get black berries instead.

Except mine is still small. It went in this year and it's nowhere near what it will be — a couple of metres and more, given time. Which is partly why the smultron is useful right now. A barrel with one young shrub in it is easy to forget about, and a young shrub is exactly the thing that shouldn't be forgotten about. Now there's fruit at the edge, so I'll be over there anyway, and while I'm crouched down picking I can see whether it's dry, whether anything's chewing it, whether it's actually growing. The berries are a reason to check on the tree.

The smultron underneath does the opposite job visually. Low, matt, unremarkable green. White flowers scattered rather than massed. White is the right call against something that dark — a coloured flower would just look like it was trying. And the berries, when they come, should be small red points under all that black. They're meant to go red to nearly white to a faint pink depending on how much sun they've had, which will either be lovely or look like the fruit hasn't ripened.

There's a practical side too. Once the elder fills out, the ground in its shade goes dry and dim. Parksmultron grows at woodland edges in the wild, which is more or less the same conditions.

When planting i just pulled the plants apart — decent root on all of them, pushed them into the rim where the compost had slumped away from the wood. Firmed them with a thumb. Added grassclippings on top to add more slow-release nitrogen to the soil. Watered.

Let’s see how much berries they will produce and how many runners will overflow the barrel throughout the season.