Growing a Garden In a Groundcover
Mike here: I've had the honor of speaking at the Phabulous Philadelphia Flower Show pretty much every year since sometime back in the early nineties; and thanks to our magnificent friends at the Show, we were able to record this year's talk—a lively Q & A with a great crowd of almost 400 people—to create a special 'live' edition of our Public Radio show, You Bet Your Garden…
The big question, however, was what to do for a Question of the Week at the end of the show. But when we reviewed the audio bits to decide which questions and answers to include in the show, one jumped out as the perfect choice for an expanded answer: A young woman who wondered if there was any way she could facilitate some landscape plantings into an existing bed of ivy…
Which seems like a relatively impossible situation, as 'ivy' is clinging, self-supporting, invasive and darn near invulnerable. But then this image popped into my head—BIG planters, buried like a foot deep into the soil right in the middle of the ivy. (I'm hoping this is an original thought; and if it is, it's one of my best.) Big, durable containers made of something that won't crack apart in areas with winter freezes, like heavy plastic or other freeze-proof material; certainly not terra cotta or ceramic. If the area is large enough, those big wooden half-whiskey barrels you see at garden centers would be perfect!
And the bigger the container, the better the chance that perennials or cold-hardy plants like pansies would survive in them over the winter. Or salad greens, at least deep into the Fall. Or—here's another nice image: Spring bulbs!
Let's talk this through. Say you install the containers 'now' (in the Spring) and grow annuals in them over the summer. If the area is sunny, you could get the look of ornamentals combined with some nice edibles by growing colorful hot pepper plants. Or those 'mini-bell' sweet peppers. Or long, thin gourmet neon-colored eggplant varieties.
And this idea cries out for some herbs as well—many of which would do well in a shadier situation. And if the sunlight is really scarce, shade-loving bedding flowers like begonias and impatiens.
Then when fall arrives, replace the plants of summer with cold-weather-loving pansies as soon as they're available. Then right around Halloween gently pull up the pansies, plant Spring bulbs around six inches deep and replace the pansies overtop. Those pansies are going to keep blooming through most of the winter—maybe all winter if you don't get ice storms; and then the bulb leaves and stalks would just emerge around and through the pansies in the Spring.
And if you plant early-blooming bulbs, you'll have lots of time to let their greenery turn naturally brown before the pansies start to fade (because if you let those leaves absorb enough solar energy, the bulbs should bloom again the following year).
Or if you don't want to keep up with succession plantings, you could choose cold-hardy perennials that have some kind of four-season interest. Just remember than in cold climes, plants in containers should be rated to survive the next USDA Zone 'down' from you. (For example, if you're in Zone 6, choose plants rated for Zone 5.)
Now—I hear you asking: "But how are we controlling the ivy?"
And the honest answer is that ivy cannot be 'controlled'; but it can be managed.
Here's my plan. Use a sharp shovel or something like an ice-chopper to sever the ivy and then remove a circle of ivy and soil that's slightly larger than the base of your container. Dig down around a foot and use a garden fork to break up the soil in the bottom of the hole for good drainage. And make sure your containers have super-good drainage as well. At the Flower Show I think I suggested maybe even removing the entire bottom of the container if it's appropriate to the material to insure perfect drainage.
Then fill the container with a mix of about two-thirds of a light, loose soil-free mix and one-third compost; with maybe some added perlite (I'm a fool for perlite!)
But what about the ivy?
If the containers are large enough and you sink them deep enough and do the right prep work up front, the containers sides should double as edging and keep the ivy on the outside. Then it's the gardener's choice: Weed-whack the sides on a monthly basis, prune or 'edge' the ivy at the very bottom on a regular basis, or let the ivy crawl up the sides until it reaches the top and then prune it before it goes over the lip.
I really like the idea of ivy covered containers; and now I'm going to suggest something even wilder. Maybe don't 'plant' anything in the containers. Instead, have some sort of trellis in there; maybe even something like a big steel model of a structure like the Eiffel Tower. Then let the ivy come up, over, in, and up to make a living sculpture. It's all one plant, but now its three-dimensional, not just a flat surface. Just prune the ivy every once in a while to keep the shape you want.
If there's enough room, maybe have some containers with 'outside' plants and a big 3-D 'ivy trellis' in the middle. And if you're working with a non-climbing, better-behaved ground cover like pachysandra, just sink the containers and plant in them. Either way, it's really going to transform the space.