Sunday, July 22, 2012

Forever foxgloves!


 If I could pick one genus of shade loving plants I would not want to live without, I would pick the foxgloves without a second thought. Thanks to Darrell Probst, Epimediums are far more numerous and variable (I'm tempted by these, I admit), Primula is fabulous, but most species of primrose need far too much irrigation to be practical for most people. Hellebores are terrific, but the flowers (except, of course, for H. niger) for all their improvement are still a trifle glum for my taste.

 Ironically, the only foxglove commonly grown in "conventional" Denver gardens is D. purpurea, which is the least satisfactory in my opinion. It needs far more water than the other species to do well, and it is one of the few that is biennial. The one above came to me as Digitalis fontanesii, which has been lumped with D. grandiflora: the latter has a large range, and I suspect this is a regional variant--both are worth growing! [I stick to the old name because I see distinctions that evade the weary eyes of botanists poring over dried husks of plants]...


 Here is more typical D. grandiflora, growing at Denver Botanic Gardens: much taller, with less vividly colored flowers and a stricter habit. I have grown this plant for decades, and never tire of its crisp, proud display of subtle color. It takes a lot of sun, but I find it looks best in at least half days shade in Colorado.


This is one of the many hybrids that have popped up over the years at our various gardens: this one at Plantasia at DBG: probably grandiflora crossed with ferruginea (see below), but I could be wrong. Alas, hybrids are almost always sterile!


My current favorite (probably because it is the one I have obtained most recently), Digitalis parviflora may have "parvi-" "floras", but they are bunched so charmingly, and the honey-amber-caramel coloration is irresistible. I believe I have seen this in quite a dark chocolate brown--a form I would love to grow as well.

Alas, my best pictures of this are still on transparencies: this has been ridiculously lumped with the common, tall Digitalis purpurea (supposedly as "var. purpurea") to which I say "pshaw!": this is utterly distinct from the giant biennial: it makes a much hairier, trim rosette, and produces distinctively shaped, wonderfully flared trumpets over a very long season--these can be deep, crushed raspberry red. It is a pretty long lived perennial (I have kept them five or six years), and loves dry shade. It superficially resembles the better known D. thapsi: I grow the two nearby one another and they are very different indeed.

This has been one of the highlights of this year: I finally have gotten Digitalis heywoodii ("D. purpurea var. heywoodii" according to the botanists.) Imagine a compact common foxglove, only with wonderfully gray foliage and crystalline white flowers....only it's perennial!


I finish with Digitalis ferruginea, another bronzy species that can tower to six or more feet tall. It thrives in a variety of sites and soils, and though the individual plants can be monocarpic, they invariably self sow and persist like sound perennials. The pale primrose color in the background is yet another foxglove, in this case Digitalis lutea, one of the smaller flowered sorts. But all indispensible...

And there are many more I have not discussed. All of these have settled down in my home garden to many niches. Did I mention that they make outstanding cut flowers? Easily grown from seed, and some can even be divided. They are tough and carefree and persist year in year out, blooming for months at a time, and looking clean and attractive even out of bloom. Each year my garden seems to have a few more patches of  them.....but never quite enough!

8 comments:

  1. When I think of wonderful shade plants things like Collinsia verna, Cypripediums, Dicentras, Epigaea reptans, Erythroniums, Galearis spectabilis, Gaultheria procumbens, Geranium maculatum, Goodyearas, Hepaticas, Heucheras, Iris cristata, Jeffersonia diphylla, Mertensia virginica, Sanguinaria canadensis, Phlox divaricata, Polygonatums, Silene virginica, and Trilliums come to mind. Even some grasses like Bottle Brush, Wood Reed, and Woodland Brome. Much different than your favorite for shade.

    James

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  2. I cut my horticultural teeth on Eastern woodland wildflowers, and love them dearly: I grow most of what you list. And I dote on ferns and the wealth of Asian woodland treasures that have flooded the marketplace in recent decades (let's not even talk lilies and orchids): truth be said, these all need a lot of soil prep and fussing: the Mediterranean woodlanders like Digitalis, Acanthus and Cyclamen are much more forgiving of our alkaline soils and dry heat in summer, not to mention they have far more protracted (and colorful) bloom seasons: perhaps they don't do for you what they do for us. But my gardens seem to have more and more of them each year, while the American woodlanders persist, and merit a bit of pampering of course! But all this is very subjective and personal: I may be biased since I am a transplanted Mediterranean myself, as it were...

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    1. I have grown Digitalis grandiflora. I liked that species. I have also grown Digitalis purpurea. Digitalis purpurea did not self sow for me. Therefore, my experiences with it were short. I did not want to coddle little plugs just to grow plants that take two years to bloom once. The main thing I have against Digitalis is nurseries tout it as a hummingbird attractor. Hummingbirds may check it out, but it is definitely not a favorite.

      There is some sort of Digitalis that has established itself in a local savannah. It it quite different than any of the species you posted because the flowers hang down. However, the color is similar to that of D. ferruginia. It appears to be perennial. I have no idea of the species identity.

      If I had a choice, I would have a native Aureolaria instead of a Digitalis.

      Do you grow Mahonia repens. That would seem like a good shade plant for Denver.

      James

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  3. I'm somewhat embarassed to admit I thought they were all biennials! Now I must realize I need to research these more :-)

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  4. Most are very perennial, Scott: at least in our hot, dry climate! I would LOVE to know which Digitalis has become a weed in Illinois: it would probably be a good garden plant for us, James: I know that Digitalis lanata (alas, biennial for us) has naturalized in a few midwestern states. I don't know any of the reliably perennial species that have done so.

    I have admired Areolarias in books, and would LOVE to grow them, but are they not parasitic? I have never seen them offered in a nurCsery catalogue: a great quest for sure.

    Mahonia repens is a superb groundcover here for sun or shade, moist or dry. Most plantsmen love it, but it is a challenging nursery crop, and the average garden center type finds it a bit scruffy. Just realized I don't have any at my house: I could use some in a shady dry border; thanks for reminding me (over 6000 taxa in my half acre, and I overlooked a classic! Shame on me).

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    1. "Aureolarias ... are they not parasitic?"

      The experts say they are hemi-parasites. That should not necessarily stop someone from trying to grow them. A number of other parasitic plants have been grown well by those doing ecological restoration. I see a lot of Pedicularis canadensis and Seymeria (Dasistoma) macrophylla in local restorations. I've heard of reported success with Comandera umbellata. I have one seedling of Lithospermum canescens growing without a host. However, it appears to suffer in the heat. Luckily, I am also growing its constant companion in our area, Carex meadii. I need to combine the two and see if it makes the L. canescens happier.

      Although beautiful, the Aureolarias are rare in my area because of our predominantly limestone soils. It would be preferred if seed for cultivation were obtain from populations further East where this species is more common.

      James

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    2. I really would enjoy seeing your restorations some time: so many treasures come from the tallgrass prairie (Silphium, Echinacea, Penstemons, grasses of all kinds) and yet so many more are out there!

      I commend your experimentation! Keep us posted.

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  5. I really cannot take credit for the restorations in my area. I have helped, but not a significant amount. Much of the credit would have to go to early planners that set aside 11% of my county as open space. More credit would have to go to pioneers in the field like the creators of the John T. Curtis prairie restoration at the University of Wisconsin and the Schulenburg prairie restoration at the Morton Arboretum. Local restoration efforts were initiated by people like John Balaban, Jane Balaban, and Stephen Packard. These restorations occurred on the old pastures and farm fields that had been preserved as open space. Those who initiated the call of restoration would not have proceeded far if it was not for all the people who dedicated themselves to the cause. These people are too numerous to list. It has been these thousands of people, providing many millions of dollars of free work to improve public lands annually, that made what is occurring today possible.

    James

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