Carlotta Paulsen-Boaz is a member of the Northeast Tennessee Master Gardeners. She lives and gardens in Kingsport, TN.

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The Underappreciated Biennial
by Carlotta Paulsen-Boaz       #Blue   #Colorful   #Flowers   #Orange   #Purple   #Yellow

Icelandic poppies are as tasty to rabbits as they are beautiful to people. 1

Fans of perennial flowers admire both their longevity in the garden and their capabilities. Where they once planted a daylily, by division, they can have three or more clumps in a few years. Fans of annuals tout their quick results and their lengthy bloom period. Pop in your six-pack and, if it isn’t blooming already, it soon will be — and will bloom for months on end.

No wonder biennials are the Rodney Dangerfields of the flower world: they don’t bloom the year they are started, and they survive only one more season. It seems the worst of both worlds. Growing biennials from seed may appear more work than it is worth, but there are good reasons to try. There are even good reasons to treat some perennials as if they were biennials.

Longevity: Many biennials self-seed with abandon. You will have these plants for years to come, at no further effort, as long as you don’t accidentally weed out the seedlings. It is like having a perennial, albeit one that wanders about. These are the biennials I think of as “grandma’s garden plants,” classics that proliferate: sweet Williams, rose campion, forget-me-nots, honesty, dame’s rocket and foxgloves.

Timing: The best time to sow biennial seeds is at the slowest point in the gardening season — late summer. It is too hot to weed and the grass is hardly growing at all. Why not spend a morning sitting in the shade starting up pots of seeds? It’s warm and sunny enough that the propagators, soil cables and overhead lights needed in March are unnecessary. Timing isn’t critical; whenever it suits your schedule is fine.

Flower power: Biennials provide an unrivaled burst of bloom. Their first year’s energy was squirreled away and in the second year can power more blooms than any annual could produce at once. Since they are programmed to die afterwards, they hold nothing back (unlike a perennial). An additional bonus is that many bloom at a gap time, after the spring bulbs and shrubs are done, but before the big summer bash of bearded irises and roses.

Avoiding the heat: Growing cool weather-loving perennials like lupines, delphiniums and Icelandic poppies (also hardy annuals like pansies, love-in-a-mist and larkspur) as biennials enables you to finally enjoy many classic English garden flowers that are intolerant of the South’s heat and humidity.

Evading disease: Some plants are doomed to die an ugly death, and the ugliest I’ve ever seen is when hollyhocks succumb to rust. It is a given if they are grown as perennials — the only question is how long it will take. So avoid it: grit your teeth, pull out the hollyhocks after bloom and start a fresh batch in August. They are about as difficult to sprout as those bean seeds you started in kindergarten.


Getting Started

While everyone has their own seed starting techniques, most are based on springtime conditions. There are some challenges unique to summer like intensity of light, heat and potentially high pest populations.

Always keep in mind how strong the summer sun is. Clear covers and direct sun create ovens; keep seed trays out of direct sunlight at all times. Once the seedlings are well-established, morning or evening sun can be tolerated but even then remember this equation: black plastic pots plus wet soil plus direct sun equals steamed roots. I find a cold frame with its lid propped open to be an excellent spot for growing seedlings, as the lid diffuses sunlight. As a bonus, the cover also protects seedlings from sudden summer downpours.

Keep a close eye on moisture levels in the soil. On one hand, potting soils will dry out much faster in the summe heat. On the other hand, damping off can seemingly occur instantaneously at these temperatures. Sow seeds thinly!

There is no hard and fast date by which you must set plants out in the garden. Aim to get them in at least a few weeks before the typical first frost. The more time they have to establish a good root system, the more impressive next year’s performance. I plant mine as the worn-out summer annuals are pulled out (with compost and a little fertilizer added to refresh the soil).

When planting forget-me-nots, remember they will be with you forever, spreading throughout the garden
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Common Problems

It may seem trivial, but seeds can be difficult to find for sale in late summer. Plan ahead. Buy your seeds in the spring or hang onto your catalogs and order in summer. For many of the old-fashioned flowers, fellow gardeners can be your best source. Try plant and seed exchanges. If you’re desperate, you can always buy a few of a desired plant and save your own seeds for future seasons.

Germination woes are sometimes due to the heat. If I suspect this to be the case, I’ll bring the pots inside where they (like me) can enjoy the air-conditioning. Sometimes seeds did sprout but were promptly eaten. Keeping the seedlings off the ground will help; there are far fewer slugs and earwigs atop your patio table — think about that on your next picnic. Slug bait is also and option, and it also cuts down on the pill bugs and earwigs besieging tender seedlings.

Winter losses can be devastating for a few of these plants. It isn’t the cold, but rather the excessive moisture that does them in. My worst disaster came when a wet winter rotted all but two of over a hundred English daisy plants. While most biennials appreciate good drainage, English daisies demand it.

Wildlife can also do plants in; in my yard the problem is rabbits. They are very selective in their food choices. Take preventative measures if you notice a particular planting constantly being grazed upon. I find black bird netting easy to use and inconspicuous in the landscape. The netting also serves for those spots where squirrels insist upon digging. Living inside city limits, I thankfully have no deer to contend with but, for those who do, I suspect the same plants that the rabbits find tasty are in danger of being scarfed by deer.

Slugs also produce losses. Many plants safely survive the winter only to have their tender new shoots eaten off in the early spring. This occurs before you even realize that there is a problem. Moats of diatomaceous earth have never worked for me, but there are many other remedies to chose from both chemical (poison pellets) and organic (beer traps anyone?). Especially for delphiniums, it is important to start slug control efforts early in spring.

Finally, some biennials can be too successful. Left unchecked rose campion (for one) can soon crowd out all the other plants in your flowerbed. The solution is simple — deadhead all but a select few of prolific types before they set seed.

Plants for the Novice Seed Starter

Hollyhocks are short-lived perennials that perform better when treated as biennials. 3

The honesty (or money) plant is named for itsslender seed pouches that resemble coins
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These plants germinate and grow readily from seed with no special treatment required. Many are tough enough to direct sow in the garden. For the beginner, foxgloves and mulleins are best obtained as plants and allowed to self-sow for future years, as their seeds are dust-like and difficult to handle.

Forget-me-not (Myosotis) – A truer blue in flowers is not to be found. Having said that, I have seen them offered in pink — why would anyone even consider it? Only plant forget-me-nots if you deeply love them, for they will be with you forever. They will also find their way into every corner of your garden (and your neighbors’), whether you wish them to or not. I highly recommend pulling all but a few plants before they set seed.

Hollyhock (Alcea) – These are really short-lived perennials that perform best as biennials. View it as an opportunity to try a different color every year. They come in singles or doubles with whites, pinks, yellows, reds and even a black variety that was purportedly grown by Thomas Jefferson at Monticello. As previously mentioned, they are dirt easy plants to grow from seed.

Honesty (or money) plant (Lunaria annua) – I challenge you, at 10 paces, to distinguish honesty from dame’s rocket when both are in bloom — but just wait until the silvery seed disks that earned it the name money plant form. Needless to say, with these attractive seedpods, it looks interesting even after bloom. Purple and white.

Rose campion (Lychnis coronaria) – The fuzzy silvery gray leaves of rose campion bear a remarkable similarity to a young lamb’s ear plant and are quite attractive. The most common flower color is an assertive bright pink or magenta. Should that clash too much with your other flowers, there are white and pale pink strains available. In all my years of growing this, I have yet to encounter any problems with diseases, insects or herbivores. Bulletproof.

Sweet William (Dianthus barbatus) – Hands down, this is the plant I recommend that the horticulturally-challenged grow; it is foolproof. It survives the coldest winters, never rots out and, best of all, the rabbits and slugs leave it alone. Generally seeds are found as a mixture of whites, pinks and bulls-eye forms, but oh-so-trendy strains of near black like ‘Sooty’ are also readily available. Some individual plants may survive multiple years, but they never look as good subsequently.

Plants for the Experienced Seed Starter

English daisies are cold-hardy biennials that do well as edging plants
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Stocks grow best in cooler climates. The best way to raise them in warm temperatures is as biennials. 6

English daisy (Bellis perennis) – At only 4 to 6 inches tall (blooms and all), English daisies make great edging plants. They come in whites, pinks and bi-colors. While quite cold-hardy, they are prone to rotting out in clay soils over wet winters. Excellent drainage is a must.

Icelandic poppy (Papaver nudicaule) – Gorgeous but extremely tasty — Peter Rabbit and his kin regularly taunt me by eating just the flower buds off this plant. Netting is the appropriate response. Bright whites, glowing yellows and extreme oranges are most common, but tone-downed shades like the ‘Meadow Pastels’ are also available.

Parsley (Petroselinum crispum) – An herb that has become popular in the flower garden, I initially grew parsley as a larval food for swallowtail butterflies. The caterpillars never showed, but I’ve kept it because it makes a handsome green edging plant in its first year. Because I enjoy its foliage, this is one biennial I start in the spring. It gets gangly in its second year, but the yellow flowers are very popular with bees and butterflies.

Stock (Matthiola) – Famed for their fragrance, these flowers come as both singles and doubles in tasteful pastel shades. There are undoubtedly more annual than biennial forms in the catalogs; read the fine print. As both dislike the heat, a Southerner’s only shot at stock is to grow the biennials. Even then, they are touchy to overwinter. Consider this one a gamble.

Wallflower (Erysimum) – Due to a liking for alkaline soils, this is one spring flower that can be tucked up against masonry. It also enjoys a well-drained situation. I find wallflowers to be an acquired taste — nice for a change, but when mine didn’t self-seed, I didn’t bother growing them again. Some individual plants may persist for years (in my experience, especially when they clash with their neighbors).


Photo Credits:
© Nancy Nehring -
© Heather Nye - 
3 © Richard Goerg - 
4 © David Hughes - 
5 © Christopher O Driscoll -
6 © Richard Loader - 


Posted: 02/15/12   RSS | Print


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