Louis Raymond experiments in his own gardens like

a mad scientist, searching out plants that most people have

never seen before & figuring out how to make them perform.- The Boston Globe

…Louis Raymond ensures that trees can grow in Brooklyn…

or just about any other place where concrete consumes

the dirt and skyscrapers shield the sunshine.- USA Today

 
 

NEW Trips to Take!

Myrtle's easy when the conditions are right.

 
 
 
 

NEW Plants to Try!

Louis tries to capture the exact words to describe the fleeting but deep pleasures to be found in these Summer-into-Autumn incredibles.

 
 
 
 

New Gardening to Do!

Allergic to bees? You can still have an exciting garden, full of flowers and color and wildlife.

 
 
 
 

Plant Profiles

Great Mullein

 Verbascum-thapsiforme-090910-640

 

Taller than I could touch even on tip-toe, great mullein is impressive even in death. The many spikes of flowers of this one are nearly nine feet in height. Hundreds of bright yellow flowers bring color all Summer, after which the giant plant dies quickly. 

 

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Its thick stems and the flowers' light brown remains are tough enough to stay erect most of the Winter. 

 

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Verbascums are prolific seed producers; this one plant alone may have produced many tens of thousands. Fortunately for me, my heavy soil and wet winters ensure that only a few seeds survive to germinate and carry on the colony.

 

Here's how colorful and popular-with-the-pollinators Verbascum densiflorum is when in flower. 

 

 

 

Here's how to grow this easy biennial:

 

Latin Name

Verbascum densiflorum, also known as V. thapsiforme

Common Name

Great mullein, Dense-flowered mullein, Giant mullein

Family

Scrophulariaceae, the Figwort family.

What kind of plant is it?

Biennial.

Hardiness

Zones 3 - 9.  The genus Verbascum is strikingly cosmopolitan in distribution. One form or another of Verbascum is established in every state in the US, including higher-elevation portions of Hawaii.

Habit

A thick basal rosette of broad fuzzy, semi-evergreen foliage that, in its second season, produces an erect and, often, much-branched candelabra-like spike of flowers. The arms of the candelabra lean outward only briefly, before pointing vertically.  

Rate of Growth

Fast.

Size in two years

Verbascum densiflorum is normally a biennial. The first-year rosette can be two feet and more across. The second year, the flowering spike can be eight feet tall and taller. Only in the case of late sowing the first season would a rosette persist as such through its second year, delaying flowering until the third. 

Texture

The rosette's large foliage is as coarse as can be—but, then again, is therefore a great contrast to smaller-leaved neighbors. The branching flower spikes are authoritative and architectural, with enough separation between the branches to ensure that the plant's imposing size is saved from being merely bulky, let alone obscuring.  

Grown for

its easy height: the flowering stem is rigidly erect and nearly woody, like that of a sunflower or hollyhock. Grow Verbascum densiflorum as a self-supporting relief from Aconitum or Delphinium, whose impressive height is only maintained by attentive staking—as well as from most forms of Aster, Helianthus, and Chrysanthemum, whose height is best handled by the merciless reduction of cutting all stems back by half in May. This verbascum's impressive superstructure maintains its integrity long after flowering is through and the plant has died. Stiffened with a single strong stake, which also keeps the plant anchored to the ground, the candelabra will remain erect through much of the Winter. 

its long season of bloom: June into September, longer than almost any other hardy plant.  

 

its flowers: About an inch across, the bright yellow flowers are adored by bees, and bring months of high-flying color to any garden. They mature to tight light-brown clusters that crowd the vertical stems, and maintain a certain interest far into Winter. 

 

its toughness: As long as plants enjoy reasonable to excellent drainage, and half to full-day sun, they are invincible. Yes, the foliage is reluctantly evergreen, suggesting (as with, say, Cynara cardunculus) that this species isn't able to handle a "real" Winter. Not so. Verbascum rosettes survive Winters that are sustained as well as severe; the foliage dies back through late Fall and into Winter, leaf by leaf, with only the youngest, innermost, ranks of leaves retaining their green viability through the cold months. In Spring, those inner leaves nearly explode with growth, and still more emerge from the plant's center, swiftly recouping Winter's losses and then some.

 

its large, critter-proof foliage: The hairy leaves are impressive more than attractive; they are ignored by browsers.

Flowering season

Summer, and nearly the entire season. Happy plants are in flower by late June, and aren't finished until early September.

Color combinations

The mid-green foliage goes with everything, but the bright yellow flowers, with their prominent orange stamens, are comfortably at home only amid other yellows and oranges, plus the universal mixers of white and burgundy. If the flowers and stamens were just yellow, then it would be great to bring in blue, lavender, and violet.

Plant partners

It is easy to provide sympathetic and even exciting company for Verbascum densiflorum, as long as none of the near-neighboring plants is close enough to interfere with the mullein's quickly expanding basal foliage. Small or slow-to-grow neighbors are likely to become overwhelmed by the mullein's thick and overlapping leaves. This, of course, is how the plant is able to help ensure that its own foliage isn't shaded out by competition.

 

You can't pretty up this biennial's exuberant coarseness by surrounding it with tidy uniformity; a mass planting of, say, bedding dahlias or 'Knock Out' roses would look as incongruous as chintz curtains on castle windows. (I still recoil at the memory of a colony of Gunnera—whose prickly rhubarbish leaves can be six feet broad and high—that was widely skirted by hundreds of pink impatiens.) Instead, fight fire with fire. Can a group of Verbascum be sited on the hot-and-sunny side of a purple-leaved smoke bush? (A large container specimen of Euphorbia cotinifolia would provide remarkably similar coloring, foliage shape, and overall size.) What about combining Verbascum with a colony of the gold-leaved sumac, Rhus 'Tiger Eye', which also adores lean soil, great drainage, and hot sun?

 

Junipers also thrive in habitat that's friendly to Verbascum. 'Gold Cone' will mature as tall as the tallest mullein. So-called "Hollywood" juniper, Juniperus chinensis 'Torulosa', can grow even taller, and much wider; its mossy green foliage and broadly spiraling irregularity would both create an exciting contrast to the spire-like verticality of a Verbascum. If your climate is mild enough (Zone 8 and warmer) to permit the shrubby euphorbias, consider fronting a Verbascum with Euphorbia characias 'Wulfenii', whose immense heads of lime green bracts should still be effective when the Verbascum flowers begin emerging. This euphorbia's mounding leafy stems would be a great textural contrast the rest of the Summer. 

 

The best partner, perhaps, isn't a plant at all, but a large expanse of gravel. Then the huge Verbascum leaves can expand outward to the max, while the dead plants are most easily accessible for late-Summer yanking. Rake gravel over where a plant had been growing, and you'd never know it was there. Plus, the gravel is the ideal habitat for germination of the self-seeding volunteers that will carry on your colony. 

Where to use it in your garden

Verbascum densiflorum provides architectural presence, at least in its flowering season, when its overall height, the volume of its multiple arms of bloom, and the bulky mound of its large and thickly-growing foliage all demand that it be sited in full view top to bottom.  

 

Try to site where the sun will bathe the plants from dawn to dusk, and where the all-around exposure to light and air isn't interrupted by buildings or shade. Individuals growing with less than full exposure can still grow to full height, but are likely to lean.

 

A plant sited at the front of beds will usually be the most successful. Not only will it receive even and maximal exposure to sun when flowering, the basal foliage will receive it, as well, both in the first year and the second, ensuring the tallest and most vigorously branched candelabra of bloom. Frontal siting is advantageous even after the plant has completed its life cycle and has died. If you want to yank it out, you won't have to wade carefully through surrounding growth, which, at the yanking season, late August into October, will be at its most lush and tangled. Or, if you want to retain the deceased plant's carcass into the Winter, as I have in the pictures above, you'll have the same easy access for the necessary stake. 

 

Plants self-seed, favoring cracks in paving or in gravel. Happily, those locations often provide the fullest exposure to sun, best display head to toe, and easiest access for yanking or staking.

Culture

Full sun and almost any soil as long as there is decent drainage. Drought tolerant, too. 

How to handle it: The Basics.

Sow seed on the surface of well-prepared soil almost any time in Spring, Summer, or Fall. Watering in Fall isn't necessary; water once or twice in Spring or Summer, then let the seeds do the rest. Thin seedlings to a couple of feet apart; youngsters transplant readily.  

 

Unless your growing season is long, and you sowed your seeds as early as possible, growth in the first year is normally just a basal rosette of foliage. In Spring of year two, a thick vertical flowering spike emerges, growing quickly and steadily. The spike ramifies into a candelabra naturally, so pinching isn't needed. And, if you've sited your plant with full exposure, neither is staking.  

How to handle: Another option—or two!

After flowering is completed, death comes quickly. Either stake the carcass or yank it.

 

As is typical for huge biennials, the roots' grip on the soil releases as the plant dies. At the height of its flowering season, a Verbascum is anchored firmly enough to remain erect through normal Summer storms and wind. After death, even the biggest Verbascum can usually be pulled up with one hand. That said, pulling up excess or poorly sited Verbascums, even those in full leaf, is still surprisingly easy, with none of the taunting resistance of, say, dock or dandelions. And, unlike those perennials, a yanked Verbascum is gone forever: Any remaining root sections die at the end of the plant's life cycle. On the other hand, Verbascum seeds are renowned for persisting for years and even decades. If you remove a dead Verbascum, its seeds have almost certainly been shed already, and by the thousands.

Quirks and special cases

As is typical for biennials, even a single Verbascum plant can produce enormous numbers of seeds, potentially into the hundreds of thousands. Oddly but fortunately, there isn't a natural mechanism for wide dispersal of such bounty. Verbascum usually self-seeds only a few feet from the mother plant.

Downsides

In my experience, Verbascum densiflorum is free from pests and diseases. If your soil and exposure is particularly congenial—blazing sun, sloping terrain, quick drainage—almost any Verbascum could self seed to excess. With my heavy soil and nearly-flat terrain, self seeding is only enough to keep the species reliably present.

Variants

The Verbascum genus is large, and individual species and cultivars hybridize readily. To my knowledge, there are no named forms of Verbascum densiflorum.  

Availability

On line, but rarely.

Propagation

By seed.

Native habitat

Verbascum densiflorum is native to Europe. 

 
 
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