perennials – The Garden Professors™

Update on our bare-rooted perennial garden

Two years ago I installed a pollinator garden in early July. This goes against my recommendation to install plants in the fall, when roots have longer to get established and less stress is felt on the rest of the plant. But I wanted to see what would happen if I was careful to mulch well and keep it irrigated. Oh, and did I mention I was going to root wash every one of them? (Be sure to look at that process in the link from 2018.)

I reported on progress last year, and this year shows even more vigorous growth by nearly all the plants. Two of the three ‘Bandera Purple’ lavender died over the first winter, as they were marginally hardy (USDA 7-10) for our area. One straggler remains in the lower right hand corner of the photo below. The Agastache ‘Acapulco Red’ and the Verbena ‘Homestead Purple’ were planted near the front of the beds on both sides and while they survived the first year, they are now gone. My guess is that our cold snap in February 2019 wiped out those plants that were in less protected locations. Perhaps we’ll fill those spots in later with something more cold hardy, or just let the escaped Viola tricolor continue to colonize bare spots.

Overall, the garden is wildly successful in attracting hummingbirds and a variety of native bees and other insects.

The southwest garden is being colonized by violets that have hopped out of a nearby container. Wood chip mulch keeps the soil cool and moist.

The southeast garden with its invading strawberries (soon to be relocated). The tiny lavender in the back right corner is a rescue plant.

I still have a little work to do – I’m relocating the strawberry adjacent to the southeast garden so it stops invading the perennial bed. But after that I’m calling this garden finished.

Allium Fever

Ornamental onions are hot patooties. From big, bold, purple globes to small pink half-moons, there is no end to ornamental onion-y goodness out there with 30+ species and cultivars in the trade. There’s no substitute for ornamental onions in regards to architectural drama – the perfect geometric foil to wispy grasses, floral spikes, and umpteen daisy-thingies. The seed heads from the sturdier species will persist and add interest to autumn and winter perennialscapes (not sure if that’s a word).

Art-of-Gardening-COVER-3D-1 — Not one but TWO cultivars of Allium on the cover of the fabulous new Chanticleer book…

All are members of the Allium genus, just like those onions sprouting in your kitchen counter veg basket – hence the deer- and small mammal- resistance factor. However…there are some issues.

Can be short-lived. I have first-hand experience with this – plant, enjoy for a year or two, then…where did they go?
Bloom time is rather vaguely defined. Most catalogs list “early summer” or “late spring” for most cultivars. But if you want continuous purple orbs, what’s the order of bloom?
Can be expensive. Bulbs for some of the mammoth “softball” sizes will set you back $5-$7 each (the bulbs themselves are huge). This is of particular concern due to the first item.
Foliage failure. For some of the largest species and cultivars, the foliage starts to die back around (or even before) bloom time. Not a lot of time to put the necessary energy back into that big honkin’ bulb.

We already have a multi-year lily perennialization trial going in conjunction with Cornell and some other institutions. I thought I might try the same thing with Allium.

Student worker Lauren, after a long day of taking data on a gazillion lilies.

Unfortunately, I had this bright idea in November – well into the bulb-ordering season. I tried to compile as complete an inventory as I could, ordering from several vendors. Ended up with 28 species and cultivars – as much as the space prepared (check out that nice soil!) could hold, at our urban horticulture center near campus (Virginia Tech is in Blacksburg, USDA Zone 6, about 2000′). We put five or seven bulbs (depending on size) in each plot, and replicated the whole thing three times.

We’ll take data over the next three years on time of emergence, bloom time and duration, foliage duration (have a nifty chlorophyll meter that can help quantify that), some growth measurements, and perennial tendencies (or not). My hope is to end up with a really specific chronology of bloom times plus life expectancy. Yes, this was just a patented Holly wild hair; luckily I had some general funds to cover it. But I do think our little onion project will be of interest to more than a few folks, whether professional landscape designers or home gardeners. I know I’m excited to see the results ($30 for five bulbs – yeek)!

Perennial Monday: Monarda ‘Raspberry Wine’

It’s been a great summer for perennials here in the mountains of SW Virginia – plenty of rain, warm days, cooler nights. We’ve been enjoying this wonderful bee balm in our home garden for the last few weeks. ‘Raspberry Wine’ is tall (up to 5′), vigorous, and a bit ramble-y; not for the carefully-curated border, but great where it can take up some space. For those who fear Monarda’s tendency to spread, know that is shallow-rooted and very, very easy to pull up. I don’t know much about the origins of ‘Raspberry Wine’ other than it’s a Monarda didyma selection or hybrid and a “White Flower Farm introduction” – Joseph may be able to shed some light.

Monarda didyma is plenty hardy (at least USDA Zone 4) and is included on just about everyone’s plant list for either pollinator gardens or “gardening for wildlife.” The species is bright scarlet, but ‘Raspberry Wine’ has rich magenta bloom with dusky purple bracts subtending the flowers. Speaking of wildlife, it doesn’t seem to be the first choice of deer, so I’d rate it as reasonably deer-resistant. There are a couple of very-territorial hummingbirds making their home next to it – can walk by any time of the day and they’re slurping away. Interestingly, they seem to be ignoring the red ‘Jacob Cline’ down the way. My photography skills aren’t such that I can snag a feeding hummer, but did catch a less-frantic bumble bee making the rounds (above).

The clump pictured is part shade (afternoon) and the foliage is still fairly clean. I have another batch in full sun that has a bit of powdery mildew. The red ‘Jacob Cline’ is frequently touted as powdery mildew resistant but I’ve yet to see ANY Monarda didyma species or hybrid that doesn’t end up with it eventually. Just chop it back to the ground ASAP; you’ll get fresh new foliage and sometimes another round of blooms.

Uncommon Clematis

– Holly Scoggins

Here’s a couple of clematis (clemati?) you may not be familiar with. Both are easy to grow but differ from the more common large-flowered form. There is a great deal of hybridization within the genus, so many cultivars are placed within “groups” rather than described as a cultivar of the species.

Clematis ‘Princess Diane’
Texensis Group

Clematis ‘Princess Diana’ in the author’s garden.

Crossing a large-flower clematis cultivar with Clematis texensis (scarlet leather flower) resulted in this lily-shaped beauty. Pointy little buds open as four hot pink tepals; bright yellow stamens grace the center. The buds on this rebloomer just keep coming; mine has been blooming for 40 days at this point and doesn’t seem to be slowing down. The princess seems pretty happy in her part-shade (sun in the afternoon) situation in my garden.

I swear there’s a lovely wire tuteur under there…

Some catalogs/sites describe ‘Princess Diana” as reaching only 8’ in length; mine’s wrapped up and down a 6’ tall tuteur/trellis thingy at least 4 times. Guess I need a bigger tuteur (doesn’t everybody?). Cold hardiness seems to be up for discussion – some sources state USDA Zones 6 to 9, others 4 to 8 (I’m a solid 6a here in the mountains of SW Virginia, recently warmed-up from 5b).

Various pruning strategies are associated with different groups of clematis. This one dies back to the ground and blooms on new wood, so I just cut it back in early spring to clean last year’s vines out of the wire supports.

Clematis xdiversifolia ‘Blue Boy’
Herbaceous/Integrifolia Group

Clematis ‘Blue Boy’ scrambles through a deciduous azalea.

‘Blue Boy’ is one of the herbaceous clematis, resulting from a hybrid of Clematis integrifolia and C. viticella. Multiple stems arise from the crown and scramble, flop, and otherwise meander through and over anything in the vicinity. Lovely blue-violet blooms festoon the stems from early June through frost (“festoon” is one of my favorite words – need more opportunities to use it!)

The rosy stems contrast nicely with the ornate foliage of Ligularia japonica.

Despite its delicate appearance, this is a very tough and cold-hardy (Zone 3!) clematis. Enjoy all summer, and then chop ‘Blue Boy’ back with the rest of your die-back perennials in winter.

Linked is a wonderful, detailed piece by Julie Lane-Gay on the herbaceous clematis group:
http://www.pacifichorticulture.org/articles/better-in-relationship-herbaceous-clematis/