I’m a pretty intense gardener. So when I love a certain specimen, I tend to use it with great abandon. Such was the case with Robinia pseudoacacia ‘Frisia’ and ‘Purple Robe’.
I first came across this specimen on a trip to London in late spring, close to two decades ago. I was taken aback by its delicate, lime colored leaves in contrast with all of the green leaved perennials that I planted around the base of its trunk. I made note of it and knew that I had to get at least one for my garden.
It happened in 1991 when my garden went through a major renovation: I transformed a steep sloping hillside into a garden with three levels by building extensive retaining stone walls. With two wide island beds on the left side of the steps at the top level, I felt that a strong statement was needed as a focal point as one walked upwards.
In researching robinias, I discovered that they’re extremely fast growers that can thrive in poor, dry soil. At maturity, they’re 30-50 feet tall and are hardy in USDA Zones 4-9. I was ecstatic to find out that they would fit perfectly in my garden; or so I thought.
I decided to plant 3 Robinia pseudoacacia ‘Frisia’ on either side of the steps in a triangular shape. I ordered them from Gossler Farms in Oregon, a terrific source for unusual shrubs and trees.
Over the next 2 years, these 6 trees bloomed into a canopy of magnificent yellowish/chartreuse blooms in the spring, followed by racemes of large, fragrant white flowers. Because they were only 5-6 feet tall at this time, one really felt covered by their beauty when perched at the top of the staircase. After the flowers bloomed, the trees became inundated with seed pods that rustled in the breeze.
I was so enamored with their fast growing, willowy, chartreuse colored leaves and fragrant white dripping summer blooms that I also began to use them with gusto in my clients’ gardens. Design wise, these tough trees never disappointed: they were always a standout as a backdrop to sweeps of perennials.
After a few years, quite self confident and patting myself on the back for making such an inspired choice, I thought “If I have a good thing going, why not add some more? ” In a long extended sweeping bed abutting my neighbors property line with evergreens acting as the buffer point, I did just that: planting 3 more Robinia pseuocacia ‘Frisia’, siting them in scale to the 6 already planted.
For the first 5-10 years of their life, I absolutely loved my robinias. Outside of my Davidia involucrata, the robinias were the most ‘oohed and aahed’ at trees when garden tours or groups came for a visit. Yes, they’re a bit of a nuisance when a storm hit: their thin, brittle branches would break off and strewn themselves all over the garden. And when their fragrant flowers turn into seed pods, although the leaves retain their lime color, by the time the end of the summer rolls in, their startling beauty fades: they become ‘just another tree with delicate leaves’.
At the same time that I planted one set of robinias, I bought one as a gift for Chanticleer, a public pleasure garden in my neighborhood. Over the years, the gardeners have kept it pruned as a medium sized, free form shrub in a herbaceous border. It looks stunning, much like a Catalpa bignoides ‘Aurea’ (Indian Bean Tree) doeswhen maintained as a shrub.
Although I added a few rows of yews and tried to emulate Piet Oudlf’s style of undulating them (well, at least I tried), my cold looking, steep front yard was still in need of some delicate curb trees to soften it up. I began to research out other robinias. In spring in one of the gardens at Hidcote, I was taken by the robinias maintained as large shrubs interspersed with a plethora of roses and perennials. Their delicate, rose-pink blooms were delightful. Consequently, when I found Robinia pseudoacacia ‘Purple Robe’ in Greer Garden’s catalogue, I thought I had found another winner and immediately ordered 4 of them.
Within a season, their spring bloom of purple/pink pendant shaped racemes of blooms with dark green leaves was a knock out. People walking or driving by would literally stop and stare.
OK, so now I’ve given you the history of my relationship and love affair with these seductive trees. Let me tell you the down side of their personalities. Because they’re so spiny and brittle, as they mature, more than a few branches, some of them major, break off of the tree.
Secondly, their fast growth is problematic. Since I don’t buy into the theory of topping off trees, I was unable to keep their canopy in the back area, low and welcoming. Thirdly, the shape of the trees had to be altered over several years of pruning. That ‘s because so many of the lower branches broke off, many remaining ones had to be pruned to keep the trees looking symmetrical. Within 7 years, there was no sense of a canopy and the branches became so high that the only place one could view their beauty was on the lower levels of the garden.
And finally, their worst characteristic is their rampant self-seeding anywhere and everywhere. The first few times this happened, I thought,” How charming, I can give them to my friends.” But each season, I had to pull out at least 2 dozen not so small seedlings(in borders and grass), along with cutting back dozens on the edge of my woodland that had become humongous. Whether or not they’re labeled invasive, I don’t know. But in my humble opinion, they most certainly are!
Would I use these trees in my garden again? No way! My one exception might be only like Chanticleer did: as a standout shrub in a herbaceous border. Perhaps then
one could keep this wild specimen under control while still enjoying its gorgeous color and fragrant blooms!