Understanding Biennials

Do you know what a biennial is? I have been working on the front lines in my garden center for over 40 years and I can tell you that most people don't understand how this particular category of flowers work. When I ask them, the most common comment is "they bloom every other year, right?" 

Well. Sort of. Biennials have a very particular life cycle. You sow seed. The seed germinates. The first year, biennials grow leaves only. They live through the winter. The second year, they bloom. After blooming, they set seed. If you leave the seed to ripen on the plant and collect it, you can sow that seed for next year's foliage plants and the following year's flowering plants. You can also buy seed of biennials. That is how I got started.

 

Show above is my latest success story in my quest to grow biennials from seed. I bought Sweet William seeds off the racks at Natureworks two summers ago. I sowed the seed in flats in June or early July. By fall, the seed had germinated and grown some true leaves. I carefully pricked out the seedlings and potted them into 4" pots. I put flats of these plants in my cold frame for the first winter. And I had LOTS of plants! That's the beauty of growing from seed. You get a LOT of plants. The following growing season I tended and fed my plants and, in the fall, I planted them in every available opening in my perennial gardens. Then I forgot about them. In early spring of this year I was thrilled to see them coming up. Everywhere. In late May, the first flowers started to bloom and they are just amazing. Tall, long lasting, and unbelievable cut flowers. The problem is, I didn't start any seed LAST summer for foliage plants this summer. So, I will let my Sweet Williams go to seed and collect the seed and sow it BUT, I won't have flowers next year, not until the year after. 

Confused? Let's consider hollyhocks (Alcea ficifolia). These are also technically biennials although sometimes last year's blooming mother plant will come back after the winter. BUT, these plants are usually weaker and often very susceptible to disease and rot. So, it is always best to collect the seed from your hollyhocks when it is ripe and sow it or scatter it in place and look for the babies to appear next year. 

The seed pods have to turn brown and, when you crack them open, the seed has to look like this picture above. I find that the scattering method doesn't work that well for me as I have a very crowded garden and the seedlings don't get enough light when emerging to survive. Therefore, I usually plant up some of the seed and pot it on and overwinter it and then put larger plants in my gardens where I know there is room. (That often means removing something else like a giant clump of self-sown asters!). 

Here is a picture of a self sown baby hollyhock plant that landed in one of raised beds. It will not bloom this year. Hollyhocks have long tap roots and, if I was going to dig it up and move it, I should have done so when it was tiny, the instant I spotted it. 

But this is why I do it. Look at this amazing hollyhock plant growing in a bed along side of my driveway last summer. I actually tied it up to the evergreen behind it! It was simply breathtaking.

The next biennial that I grow from seed are foxgloves (Digitalis purpurea). These act exactly like true biennials should. The first year plants are small and leafy. The second year plants bloom. Then you MUST let the seed ripen. It is small, like dust. When it drops, you can't even see it. Sometimes I take ripe stalks and shake them around my gardens to spread the seed. But, my very full and crowded garden prevents most of them from sprouting. 

This year, on May 28th, I sowed a couple of packets of Digitalis purpurea seeds in a flat outside. Imagine my delight to spot the tiny, baby seedlings appear on June 9th! Now I am going to let them grow until they get big enough to transplant. I will then move them to 4" pots if they are very small by late fall and keep them in my cold frame or, if they have gotten big enough to withstand a CT winter, I will plant them in the ground. 

I will have HUNDREDS of foxglove plants when this process is done. Yes! That is the goal. 

It is important to learn to recognize the baby foxgloves when they do come up as they may appear in unexpected places. Unlike hollyhocks, they do not have a long tap root and are easy to scoop up, pot up, or transplant to a new spot when you find them.

A well established stand of foxgloves will reseed endlessly. It is just getting through the first two years of the cycle. That is why I often tell people, when establishing all biennials, to put in PLANTS and SEEDS at the same time. In fact, if you can find them, plant a young plant, an older plant that is in bud, AND seeds. That way you will always have something in bloom and something with foliage for the next year. 

The other benefit of growing plants from seed is you can grow very specific colors and varieties. I snapped this picture of a pure white biennial foxglove in the perennial gardens of Elizabeth Park in Hartford. You can buy seed packets of single colors such as pure white and apricot, thus creating color combinations that 
will turn heads!

Why not give it a try? Grab some seed packets of biennials and sow them this summer. You become as fascinated as I am by this process and you may end up having a garden filled with old fashioned flowers that will give you pleasure for years to come.