BIENNIALS

by keith kurman

GARDENERS and POETS

After strolling through our display gardens at Vineyard Gardens Nursery a couple years ago, a famous landscape architect remarked at how magical and elusive the biennials were. This is a particularly encouraging thing to hear, not that we weren’t already aware of how beautiful they were, but that our diligence was rewarded by someone noticing the skill required to achieve the effect.

An important part of gardening is weeding and there are two axioms gardeners use all the time,

“A weed is a plant growing in the wrong place.”

“One man’s weed is another man’s wildflower.”

With this in mind, it is important to attend to the needs of a particular garden. It can be difficult early in the season to distinguish which seedlings are weeds and which are plants you want in your garden. This is true of both biennials and annuals. We’re not talking about annuals here so lets stick with the biennials.

Luckily, biennial seeds tend to germinate in warmer weather, in late June and July. They also germinate readily from fresh, current season seed. So you have to be particularly vigilant when weeding the garden from July to September so as not to weed out the first year cycle of what will be next year’s magic. If you are thinking in these terms then you can have biennials flowering every year, not every other year as you might expect. The difference being that they are just not the same plant as the year before but their progeny. It seems like a simple enough proposition but that hop-scotching of years is much of what makes biennials so challenging but also so rewarding, unexpected and magical. To further complicate the issue, some biennials will carry over into a third year. They will however be not so vigorous and can carry over with them diseases and pests that can spread to your fresh stock. Once they have gotten to this point it is better to remove them, however hard it might be to toss them on the compost pile.

A hollyhock

shot up to meet

the summer solstice

(Masaoka Shiki)

MYSTERIOUS, LIKE MAGIC

Biennials are by nature herbaceous flowering plants. That may seem obvious but those flowers are what we are going for to achieve the effect. For clarity let’s review the difference between the growth habits of the plants in our flower gardens.

Annuals have the shortest life cycle. Their seed germinates in the Spring, they then rush to develop leaves, roots, flowers and seed in one short growing season before dying at the first frost. Annuals are determined to set seed in their first year so they are well suited as cut flowers because if you keep cutting the flowers off the plant it will continue to produce them until they manage to set seed. If those seeds are left on the plant or collected, saved and sown the following year, will produce an annual crop of flowers. Typical examples might be, Poppies, Cosmos, Zinnias, Impatiens or Petunias.

Perennials can be a confusing group but the axiom associated with them goes,

“Perennials are plants that, had they lived, would come back year after year.”

There is wisdom in this simple statement. Hardiness, growing conditions and pests can all challenge our best efforts to keep perennials going year after year in the garden. That said, we can best describe perennials as, flowering plants that retain a dormant crown and root system below ground through the winter, producing leaves and flowers every successive year. Perennials will usually multiply at the crown and/or by lateral roots, thus the need to periodically lift and divide them to keep them fresh and healthy in the garden. Examples of classic perennials might be Iris, Peonies, Phlox, Hostas and Astilbe, honestly far too many to list!

So you can see how biennials fall somewhere between these two groups. The great garden writer, William Robinson, in his seminal book from around 1890, “The English Flower Garden”, says, “…the line between biennial and annual is not a strict one… as the work of raising all is, to a great extent, the same.” Well, that’s easy for him to say, he was gardening in England which we know has a milder climate and sweeter soils than we do here, blurring the lines between all the flowering plants.

Quite simply, Biennials produce in their first year leaf and root and in their second year flower and seed. There are characteristics of both Annuals and Perennials within Biennials carrying with them the same caveats, that hardiness, growing conditions and pests can conspire to frustrate our best intentions. For biennials you could add to this list, over zealous weeders. Some of the most outstanding examples being, Foxglove, Hollyhocks, Sweet Williams, Campanula and Verbascum also known as Mullein.

Biennials are actually much more common than you might think, just over in the vegetable garden. The colorful, showy flowers of foxglove, hollyhock and verbascum are close relatives of some of our most common food crops. The parsley’s, mustards, cabbages and carrots are all biennials! It’s just that we aren’t growing them so much for their flowers as we are for their first year leaves and/or root systems e.g.radishes, carrots etc. We’ve all seen our parsley overwinter then with the advent of Spring ‘bolt’ to flowering at which point they become tough and bitter. So we start them every year fresh and harvest them for their first year’s foliar bounty. A second year carrot is a tough and tasteless thing but it is producing a flower of sorts, just not as beautiful as say, its more ornamental cousin, Queen Ann’s Lace.

Now we are really getting into the “weeds”! Some of our favorite biennials for early-mid summer flowers like Money Plant, with its silver dollar-like seedpods in late summer, Lunaria annua, is part of the group that also represents Dame’s Rocket, Hesperis matronalis and Wallflower (Cheiranthus) all of which are in the Mustard family and are often considered weeds due to their tendency for prodigious re-seeding. Queen Ann’s Lace, Daucus carota, from the carrot family, is also considered a weed but they are so lovely growing along the roadside usually together with its associate, Chickory, Cichorium intybus, with its clear, cerulean blue flowers. Both biennials, Chickory and Queen Ann’s Lace are hardy, naturalized exotics not generally considered garden worthy. But this takes us in another direction…

THE SOUL OF THE GARDEN

Where to ‘place’ biennials in the garden can be challenging. The problem being their two stage growth. In the first year while they’re developing their deep root system, the basil foliage stays tight and low to the ground. Then in their second year they produce a fresh batch of foliage before ‘rocketing’ their flowering stalks up several feet above the base. Left on their own they will often choose the most inappropriate spots, coming up in the crown of your Peonies, in the stonework of your retaining wall or crowding around in the front row. Striking a balance between random and orderly should be our objective. This is easier when planting out starts, but only a little more work when dealing with self-sown seedlings. The seedlings will tend to appear in clumps in the general vicinity of the parent plants. You’ll be able to recognize them once they’ve formed their ‘true leaves’ and at this point they are ready to be thinned and transplanted. Thinning will enable the young plants to to develop into larger, stronger plants and provide dozens more for transplanting. Whether in the flower garden or out on the margins it is often the rouge by the stairs or under the Viburnum, the unexpected, that brings the most charming effect.

This year at Vineyard Gardens we’re going to try and help you get going with introducing biennials into your gardens. We will be starting a fine selection of some of the best varieties later in the season than we usually do. In order to offer smaller, healthier plants at the right time for planting out we’ll be starting the seed in late June making them available during mid to late Summer. We will also be producing a number of rare, exceptional perennials at this time. We hope that you’ll plan on selecting and planting out several varieties during that late season window, basically mid-late July through September. We’re lucky here on the island to have a long Autumn growing season that will allow a good couple of months of growth from a September planting out.

It’s never too early to start planning, so here’s looking forward to seeing you at the Nursery! We may be doing one of our Saturday talks this summer on biennials, let us know if you would be interested!