Little Sweetheart Rhododendrons
Much as I love the big, bold, beautiful Rhododendrons, I have a small garden so I grow mostly small species and hybrids. Some of my all-time favourite species are R. pruniflorum, R. sargentianum and R. campylogynum. As container specimens, all have been reliably hardy for me in the Victoria area for many years and all are easy growers.
I started with small well-rooted cuttings, originally grown in 4 inch pots and over time, have moved the plants up to larger containers. The current pot size capacities are, more or less, 3 gallons. My potting mix is coarse peat, perlite, some coarse sand and if I've got it, a bit of garden compost. I do want a well-drained mix, so there's no more than about 40% peat in the mix. I know many people are cautious about fertilizing some Rhododendron species, but I give my container-grown plants a light application of slow release fertilizer in the early spring. Since they're in pots, there's considerable leaching so I think some fertilizer is appropriate. Some of our local growers just top dress their potted rhododendrons with Seasoil (a form of composted fish fertilizer) once each spring, and this works well for them.
I keep my plants in a location where they get full sun in the morning, but by about 1 pm, they are in the shade. Good light is needed to set flower buds, so if you have some of these smaller species and they're not blooming for you, perhaps a bit more light is in order. I water freely on an as needed basis, and I make sure the drainage holes remain open since there can be problems with containers if they're sitting directly on the soil surface where the holes may gradually get plugged. I like to have some sort of top-dressing on the soil surface to prevent too much surface compaction from all the watering I do. A good layer of orchid bark makes an attractive mulch, but sometimes I use turkey grit, or small-sized pea gravel. However, if you like to show your plants, most show judges prefer to see bark mulch used as a top-dressing as they often think write comments that they think gravel isn't aesthetically suitable for rhododendrons. Personally, I like the look of gravel or grit and it lasts longer than orchid bark.
Rhododendron pruniflorum has thimble-sized bell-shaped flowers of a dusty plum colour. It's absolutely adorable in bloom. The leaves are small, a nice dark green on top and white underneath. My 6-year old plant is about 18 inches tall and 18 inches wide. Many of us grow R. campylogynum and there are several forms available - all of them are very nice. But, my favourite (and I have a couple of forms) is R. campylogynum Leucanthum. Again, the thimble-sized flowers are bell-shaped, but in this case they are white in colour. Rhododendron sargentianum has small, ball-like trusses of white to ivory coloured tubular flowers. The tiny leaves are a nice shiny green and if crushed, give off a scent. The scent isn't unpleasant, but it makes me sneeze. I have a plant of the straight species, but recently acquired a plant of the selected variety 'Liz Ann' which is stunning in bloom as it just covers itself in pure white flowers. These plants are also about 18 x 18 inches and range in age from 3 to 7 years old.
A very similar looking plant to R. sargentianum is R. primuliflorum, but, with primuliflorum, the tubular flowers range in colour from white to soft pink and even yellow. It also has scented foliage. I've just recently been given a pink flowering form of R. primuliflorum and I'm looking forward to seeing it in bloom next spring.
One of the advantages of growing plants in pots is that I can move them onto the porch when the plants are in bloom, so while the plants and their flowers are small, I can get up close and personal with them easily. You know the adage, great things come in small packages, so if you only have a small garden, consider growing some of these lovely little sweethearts.