It’s been exactly one year since I seeded the trampoline garden at my house. The 225 square-foot space used to have a trampoline on it. Now it is chock full of immature native woodland plants.

By Scott Woodbury

[This article is a follow-up to an article Scott wrote for the Gateway Gardener Winter issue 2024-25.]

 

It’s been exactly one year since I seeded the trampoline garden at my house. The 225 square-foot space used to have a trampoline on it. Now it is chock full of immature native woodland plants. If my math is correct, there are around 3,000 seedlings spaced 3.5 inches apart. That’s about 13 seedlings per square foot. There were quite a few more, because I spent the first growing season thinning the overly-successful ones, like Drummond aster and blue-stem goldenrod. When one shows up too close to a not-so-well represented species (like spreading aster, hairy mountain mint and common milkweed) out comes the commoner. This is how to ensure the greatest species diversity. There were likely too many seeds of those species in the original seed mix. You may recall, I collected most of the species here and there and received many in packets from the Wild Ones annual seed exchange. My measure was the volume of my pinch for large seed, or a half-pinch for tiny seeds. Not perfect, but it worked well-enough for such a small spec of woodland.

 

More time was spent pulling actual weeds like burnweed, dandelion, three-seeded mercury, yellow nutsedge, creeping spurge, and the fescue grass that was creeping in from the edges. These were easy compared to the thousands of red maple and birch seedlings that blew in from over the house and neighbor’s fence. 

 

One of the down sides of growing a woodland from seed, is that you can’t use mulch to suppress weeds. If you did, you would suppress germination of the good stuff along with the weeds. So whatever weeds you get (you will get weeds when you have bare soil) you have to deal with. In large-seeded projects, weeds may get string-trimmed or mowed down to 6 or 8 inches, so they don’t shade out the good seedlings. But in my teeny-tiny pocket woodland, I have the luxury of hand-pulling in my tool kit.

 

My early morning ritual involves circling the garden in search of weeds. I never tackle all of them at once, my back is only good for 10 or 15 minutes at a time. Instead, I put steady pressure on them all season long. Now with the season nearly ended, the number of weeds are negligible.

 

The species that remain (the good stuff) includes a few species of sedge, beak grass, bottlebrush grass, creek oats, pale Indian plantain, purple Joe pye, purple coneflower, Drummond aster, hairy mountain mint, spreading aster, bluestem goldenrod, columbine, giant hyssop, Ohio spiderwort, golden Alexanders, Bradbury beebalm, black-eyed Susan, Ohio horsemint, woodland knotweed, sweet coneflower, common milkweed and smooth beard tongue. The eastern blazing star never came up. I’ll make a note to add a few plugs in spring. I added small containers of three butterfly milkweeds, one garden phlox, and one sensitive fern, in addition to the black gum and short leaf pine trees that will eventually grow tall and shade the garden. One of the milkweeds supported a monarch caterpillar which then hatched out from beneath the birdfeeder hanging nearby.

 

After one growing season, there is very little bare soil showing. Next spring, when the new leaves emerge, there will be less soil showing and a near complete cover of the good stuff. At this point the garden will have stabilized considerably, though I will still be pulling tree saplings, and other weeds that blow in. I’ll always be thinning out aster, goldenrod, and anything else that tries to dominate. It is a garden after all, so it will need me to ward off evil honeysuckle, and tree saplings. 

 

Lastly, I should mention that, because the seedlings are so close together (some would say too close together), they are getting established much more quickly than normal. The seedlings are aggressively competing with each other for light and soil nutrients, not unlike they do in nature. Because they bump into each other so early in the establishment phase, their mature size will be stunted, not by nature’s standard, but by a gardeners standard. That’s the only way that 3,000 seedlings can survive in an area so small. Well that, and me keeping an eye on things. Each plant has only so much available sunlight and nutrient, and so has to struggle more than they would in a roomy lush garden. Each plant will produce a single flower stem, instead of a dozen or more that would develop in a conventional garden, where nutrients, sunlight and space are aplenty. This season produced multiple single stems of Joe pye, woodland knotweed, and a pair of black-eyed Susans. I don’t think it will ever be a gaudy display of color. That is definitely to my liking, as I am more interested in the ethereal qualities that come with over-stuffed diverse grassy seeded landscapes. Many seedlings will surely thin out naturally, or by my hand in the coming years. Change is inevitable. But the trampoline garden will also spread outward and begin to consume the lawn around it. And I think I will let it.

 

Though it has been a lot of work in the first year, and will still take time in the years to come, this little woodland garden is well on its way to holding its own. It is quickly reaching the point of stability, where the good stuff covers every square inch of soil, and where I begin to enjoy its diversity and ethereal qualities. It already mesmerizes me, the varied textures and the tiny visitors that show up like a gift on a cloudy day. I am pleased with this garden, this mini-woodland, and I plan to do more with seeds. Why don’t you join in on the fun!

Scott Woodbury was the horticulturist at Shaw Nature Reserve for 30 years and stepped down from that position in June 2022. He continues to work on contract for Shaw Nature Reserve to carry out native landscaping education and has launched his own business called Cacalia: Native Garden Design and Wilding.