Monday, August 12, 2013

Fab Late Season Annuals

My favorite selections from a year of experimentation


Thomas Rainer

The wet spring and early summer has been a blessing and curse in the border this year.  Moist-loving perennials like Mondarda and Eupatorium have swelled to gigantic proportions, growing several feet higher than they've grown in the past two years. All the while, my drier-loving perennials have melted with fungus and mildew.  I've just finished ripping out several dozen fungus-covered Perovskia and Agastache ‘Black Adder’.  It’s funny, because if you asked me last year what kind of plants would be on my list of “plants of the future”—that is, climate change worthy plants--I probably would have listed those two.  But one wet season and they are gone.

I have long complained that summers in Washington, D.C. area are essentially subtropical.  While perennial gardeners in cooler climates like Maine, England, and the Netherlands enjoy spectacular bonanzas of July and August blooms, we humidity-bound gardeners watch all but the most thuggish of our perennials flop and generally poop out.  Of course, it is entirely possible to have a beautiful late season perennial garden in the mid-Atlantic; it is just hard to have both a beautiful early season and late season perennial garden here—particularly for space-challenged gardens.  Our growing season is so stretched out (with a thirty degree temperature differential); what looks good in May most definitely does not look good in August and vice versa.    

So this year, I've invested heavily in annuals and tropicals to pump up the late season border.  I can’t tell if my foray into annuals and tropical is a strategic master-stroke or a sign that I have slipped too deep into horticultural self-indulgence. Whatever my diagnosis, I've learned quite a bit this year about combining these plants in perennial garden—including quite a few missteps (such as giant Colocasias shading out half a dozen sun-loving plants).  But there have been enough happy accidents that I thought I’d share a few of the better moments.  I've seeded almost two dozen different plants this year and tried a range of different tropicals. Here are my favorites:

Tagetes patula ‘???’ (1m tall)
Tagetes 'Cinnabar' courtesy of Gardens Illustrated
A three-foot tall marigold on loose, ferny foliage?! This strain of French marigolds is a marigold that even marigold-haters would love.  I collected this seed from a friend who apparently mail ordered it from California.  Most marigolds are dumpy little bedding plants; this little lovely grows two to four feet tall on beautiful finely-cut foliage.  After years of lusting after Tagetes ‘Cinnabar’ at Great Dixter, I’m thrilled to finally have one of these loose, landscape marigolds.  Some sources say it may be a Himalayan cultivar; others say it a true French strain.  Single orange and red flowers grow on top of a plant that more closely resembles an aster in form than a marigold.  Blooms July to November and re-seeds readily.  This year, I tucked this in a few late season holes.  Next year, I will feature this annual front and center.  Annies Annuals have several varieties of this type of marigold (Villandry & one called ‘Gina’s Himalayan’). Sarah Raven features ‘Linnaeus,’ a looser variety of this marigold with deep amber colored flowers.

Tithonia ‘Feista del Sol’
image by Jule Dansereau
Several years ago I grew the straight species Tithonia rotundifolia and was delighted with the result.  The color orange of these daisy-like blooms is so pure, it almost glows. A real butterfly magnet. The only problem was that this annual grew eight-feet tall and six-feet wide—taking up much more real estate than I could stand.  But thanks to Swallowtail Garden Seeds, a compact version called ‘Fiesta del Sol’ is available that tops out about thirty inches (75cm) tall.  The best part is that this annual never sags in the heat.  Looks as good in 110 heat index afternoons as it does in late November.


Cosmos ‘Psyche’ Series

image courtesy of Berkshire Botanical Garden
After trialing many different types of Cosmos, my favorite by far is the Psyche series.  Here’s my advice: don’t select Cosmos for height or color; instead, go for bloom size.  The Psyche series has blooms 3-4 inches wide.  That’s four times the size of some of the other varieties, one of the largest of Cosmos bipinnatus species.  I’m not generally a fan of double blooms (they always look a bit over-bred), but these double blooms are frilly without being precocious. The densely ferny foliage is a real plus for this series as well--not at all leggy like some Cosmos, but instead ferny and lush  These high-spirited, vigorous cosmos evoke late summer exuberance like few other plants. Grows three to four feet tall.  Very long lasting. Swallowtail Garden Seeds.


Dahlia ‘Arabian Night’
photo by Thomas Rainer
Early color starts cherry red but deepens to almost a black
When it comes to dahlias, there are a million beauties.  But ‘Arabian Night’ is a classic—the Sophia Loren of dahlias.  The plant seduces with its velvety texture and smoldering red color.  It’s hard to describe the allure of the color.  The flowers open a dark cherry red then mature into a deep currant-color (almost black), creating the illusion of shadow even in the full sun.  The effect is flirty yet deadly. If temptation itself were a color, this would be it.  Grows 36 inches tall. Brent and Becky's Bulbs.

Ensete ventricosum maurellii, Red Abyssinian Banana
photo by Thomas Rainer
Ensete maurellii next to Persicaria polymorpha in my garden. The banana has tripled in size since this photo was taken

No other banana variety compares.  Each leaf can grow four to eight feet long, making a stunning silhouette in the back of the border. The absolute best feature of this banana is the high gloss, burgundy foliage of the stems and undersides of the leaves.  Something about this color that blends incredibly well with grasses and other blooming perennials.  Red Abyssinian Banana has one of the best silhouettes of any of the banana selections, much more compact and dense than many of the Musa genus which eventually look like palm trees.  This is one of the more pleasurable plants I've ever grown.  Too bad it won’t survive the winter. Plant Delights Nursery.

18 comments:

  1. I hate marigolds but those Tagetes got my attention. I've been seeing some "non-marigold-looking" marigolds, and these must be the ones I've been resisting. Can't take wet, can they?

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    1. I know, I've hated Marigolds for years, but I've been having a rather nostalgic attraction to them this year. These taller ones are at least more tolerable than those poor bedding versions.

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  2. the nasty short stubby marigolds are what breeders do to a perfectly good plant to make it 'small garden worthy'!?

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  3. Nice selections. My favorite annuals are Kiss-Me-Over-The-Garden-Gate, the Castor plant, Nicotiana, 4 O'Clocks, Amaranthus and Impatiens glandulifera. All but the Castor plant are self sowers which makes life so much easier. Great post! I hope your weather returns to normal next year, whatever that is, right?

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    1. I've had a lot of fun this year with Amarathus 'Hopi Red Dye' A blast of color and a great weaver.

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  4. The tithonia - the tall type - in my front garden are getting lots of attention from passersby. I'm going to save the seeds and plant them again next year.

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    1. Isn't it fun! When we grew the larger one, it was one of the most commented plants in the garden.

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  5. I can vouch for the Villandry marigold and am kicking myself for not sowing some of the seed I saved. Masterstroke or self-indulgence, for some climates and smallish gardens, carefully selected annuals are the answer. Thanks for vetting some good ones.

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    1. Thanks for the reassurance with the annuals. Sometimes I feel like I'm undermining any design credibility I may have when I advocate for annuals. There's a real bias against them from some designers.

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  6. I'm wondering about the Perovskia siting. I fully expect you're knowledgeable about its drainage requirements, but I wonder if you might have cheated those a little given the last several drought stricken mid Atlantic summers (and last fall). Would better drainange have saved them or were these perfectly sited and doomed no matter?

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    1. The issue was less about siting than about changing drainage conditions (re-routed gutter pipe) and planting larger plants next to them that shaded them out. I've changed everything around them so much, I probably should have pulled them out earlier.

      Their definitely great plants! The siting was initially good, I just changed the conditions (and my goals) so much for the area they are in, that they no longer work.

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    2. Thanks for the clarification, Thomas. Congrats on 2.0 and the new book!

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  7. You've peaked my curiosity about the huge cosmos. I'm feeling the late summer blahs. Also I hate day lilies more than ever right now as many of the ones that I inherited with this house look god-awful right about now. On to bigger and better things. It's time to order fall bulbs!

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    1. Yeah, I've tried a lot of cosmos and never quite had the effect I imagined. The Pschye series are definitely worth considering. It's all about the bloom size (and vigor, of course). Color, height, everything else is secondary.

      TOTALLY agree about daylilies. Though they were pretty fabulous with the cool and wet early summer. Now is a different story.

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  9. Bummer about your Black Adder agastache. Have you tried Blue Boa agastache? I have one plant, which shrugged off the dampness, started blooming in late spring and is still going strong, and has been covered in swallowtail butterflies. Of course, the flower color is not actually as saturated as shown in on-line pics, but it is still lovely. Definitely gotta get me more of them!

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    1. That's my experience too, Carol. I'm a huge fan of Blue Boa based on its performance the last three years. We live in central VA and this variety beats the others we've tried by a long shot (incl Blue Fortune and Black Adder). Ours too are covered with butterflies at home and in the nursery. The only other crops that pull them in this way for us are upright seudm and several different Eupatorium.

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