In 1931, when Marjorie Hancock’s father, Leslie Hancock, established Woodland Nurseries (now called Hancock Woodlands) on Camilla Road in Mississauga, Ontario, times were tough and landscaping jobs were few and far between. A few years later, to make ends meet, the young Englishman took a winter job lecturing at the Ontario Agricultural College. To pass the long weekday evenings away from his family, he read everything he could find in the college library on growing rhododendrons. When he finally started propagating his own plants in the 1950s, he’d become something of an expert.

And, as Marjorie Hancock guides me under the hulking rhododendrons, magnolias and viburnums in the enchanting 4-acre woodland that makes up a large part of the nursery she runs along with other family members, it’s clear she inherited her father’s enthusiasm and expertise.

The rhodos her father planted more than a half-century ago in the sandy topsoil under the oaks, pines, beeches and maples might now be well-established, but public acceptance of them as good garden shrubs for cold climates is much more recent. In fact, it wasn’t until establishment of The Rhododendron Society of Canada in 1971 that local folks knew much about them at all. And it was Marjorie herself, in lectures and slide shows throughout Southern Ontario, who convinced scores of sceptical gardeners that there’s a place in every garden for a rhododendron or azalea.

“But,” she cautions, “you can’t always have what you want, where you want it. They vary so much. For sun, ‘PJM’ and other small-leaf forms are wonderful, especially for smaller lots. They can take much more exposure.”

Planting Your Rhododendron

Large-flowered rhododendrons, however, like to face northeast, sheltered from the wind, yet with plenty of morning sunshine or at least a good, bright, open sky. “People think they need a lot of shade,” says Marjorie, “but if they’re not making buds, they’re probably not getting enough sun.”

The killer is that midday sun in late winter and very early spring when exposed foliage becomes moist in the warmth, but the ground is still frozen and water cannot be drawn up by the roots. In such an unfavorable exposure, rhodos need a burlap or evergreen screen. “Wrapping them is not good,” says Marjorie, ”because the burlap gets wet and freezes against the leaves.”

“But what’s the point,” she continues, “of having an evergreen plant if you wrap it up with brown burlap in the winter? Sited properly, and out of the wind, that shouldn’t be necessary.”

Okay, Marjorie. We’ve brought home our rhodo and picked out a nice slope facing northeast without any root competition from greedy maples or ashes. Now what do we do?

“Take your plant out of the pot and gently loosen the roots, making sure they don’t circle the stem. Use a small knife to scarify (make small slashes) on the root surface. In the wild, rhododendrons grow in mountains in fairly shallow soils with the root system shaped like a hamburger bun, close to the surface for oxygen and drainage. So you should plant your rhodo on the garden, rather than in the garden.”

“Keep at least one-third of the root matter right out of the soil and mulch heavily around it with something loose and non-matting like oak leaves. Better to plant them high than bury them in a hole.”

What kind of soil do rhodos need? “Forest junk, that’s what my dad called it. Rotten leaves, rotten wood, rotten anything. So many people put garden waste in bags and out for garbage. It should be piled in the back corner and allowed to rot down. Use that, together with lumpy peat or decayed pine bark. Just be sure it’s coarse enough to provide air and give drainage.”

When should we fertilize our rhododendrons? According to Marjorie: “These plants grow in cycles. In early spring, the roots grow and the top doesn’t do much of anything. Once the plant has stored nutrients to its threshold levels, the top grows and the roots rest. The optimum time to feed them is when roots are in active growth in April and May, using a balanced product containing nitrogen, then in July and August with a super-phosphate to promote budding for next year’s bloom while discouraging late vegetative growth that might be killed in winter.”

For more information on rhododendrons and directions to Hancock Woodlands, visit their website.

Adapted from a column that appeared originally in the Toronto Sun

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