Biennials are misunderstood. They are a small group of plants with a very specific lifecycle that is often mimicked by hardy annuals and tender perennials.

The name alone causes so much confusion – some people think that they bloom two years in a row or only every other year. The reality is they do grow over two seasons, but in a 365-day cycle, so they appear to grow like perennials.

I was introduced to biennials 30 years ago when I left my herbs in the ground over winter. Pre-internet, I did not know what was happening. I was excited the parsley came back so strongly in spring. I felt like I had conquered growing perennials with this miraculous plant. A month later, it sent up a stalk and bolted. I was disenchanted, but then I started to understand the lifecycles of plants.

Hollyhock is the most famous biennial, with strong, tall spikes of flowers that seem to come from nowhere each year (as long as they are allowed to go to seed and drop that seed during summer).

Unfortunately, there is some serious mislabeling, by seed houses and nurseries, of biennials that causes mistrust of perennials. To further complicate the issue, advances in plant breeding have produced varieties that flower the first year (FYF) like an annual. The good news is that, if allowed to overwinter, the plant does present a bloom that second season. Confused yet?

The characteristics of biennials are that they bloom late spring into early summer, reseeding heavily so that plants sprout up and grow throughout summer and autumn. They go dormant in winter, enjoying a period of vernalization that triggers new spring growth and bloom early the next season.

There are actually only four main commercial cut flower crops that belong to this small subset of plants. This separates the casual gardener from the flower farmer depending on these blooms in late spring. Here in USDA Hardiness Zone 5, these four are the backbone of my June and July bouquets:

  • Dianthus (or sweet William) is a common bedding plant but there are a few varieties that make exceptional cut flowers. The Sweet™ series reliably overwinters and comes in very wedding-friendly colors such as pink or black cherry. My favorite is coral, as it acts like a red, brightening everything else up without the polarizing nature of a true red.

The easiest ones to grow are the Amazon™ series, which are definite first-year bloomers. Some call the shades in the Neon series garish, but the cherry and purple add a vibrancy to bouquets that is unmatched. ‘Rose Magic’ is a bicolor pink that is surprisingly easy to mix with other early summer flowers. In addition, when cut these have a very long vase life, making them perfect as accents in market bouquets.

  • Foxglove blooms with downward-facing bells on long stalks. They are graceful and perfect in arrangements. If allowed to go free in the garden they set seed and keep blooming from the tips into autumn.

Of course, we want to cut them before the first seed sets so we consider them a late spring option. The colors of these are especially great for weddings in whites, peaches and lavender.

It’s important to remember that not all foxglove varieties are biennials. ‘Milk Chocolate’ is actually a midsummer-blooming perennial with a rust color that blends well with Dara, giving off an antique vibe. All foxgloves are poisonous, so be careful around children and pets. (This attribute also makes them practically deer-proof.)

  • Canterbury bells are in my top five favorite flowers. The ‘Champion’ series (also FYF) have upright structured bells in bold colors like purple, pink and white. Florists especially like the ones grown tall in a tunnel. Harvest them after the first three bells open.

It is very important to beat the rain, as water will damage them. Cut near the base of the plant and it will send up additional shoots, although they may be smaller. Another important consideration is that these plants are deer candy. They will walk around seven rows of everything else to munch on Campanula.

The brown-eyed susan’s well branching little flowers make it a fantastic bouquet filler. Photo by Betsy Busche

  • Triloba (aka brown-eyed Susans) are a tall branching type of Rudbeckia that blooms midsummer and continues for weeks. These are great contenders for pinching and do need to be at least corralled so they don’t fall over. I use them as center fillers for bouquets or to create dimension in arrangements. The petals are traditional yellow-orange and the eyes are brown (thus the name). I let some go to seed and they have been one of the few reliable self-sowers for me.

Biennials self-seed for gardeners, but the very essence of flower farming is that we cut every viable stem to sell. By doing so, we completely interrupt this process. To ensure a crop every late spring, we must replace these plants at the same time they would naturally reseed.

Each of the major four can be started in June to be planted out by Aug. 1. This gives the transplants enough time to ensure the plants overwinter and reemerge in early spring. This system works because most of the plants’ growth happens in that first season. The second season is just about generating the flower then to go to seed. Again, we disrupt this process by harvesting the unpollinated blooms.

All of these are good prospects for autumn planting in a tunnel, allowing for blooms a month earlier. Canterbury bells especially prefer these conditions, resulting in taller plants and no damage to bell-shaped blooms from rain.

Others to consider include Lunaria, aka the money plant (grown for the coin-shaped seed pods). As cut flower sellers, we normally want to cut before pollination and seed formation, but this plant is prized for the seed pods, which need to be harvested midsummer before they burst.

Dame’s rocket is the most controversial biennial, as it’s considered an invasive species that reseeds in hedgerows and along roadways, strangling out native species. It’s confused with garden phlox, which is benign as a garden plant but lousy as a cut flower because it drops petals.

Rocket blooms in June in Zone 5 in charming whites and purples. The argument for these flowers is that by cutting them before pollination – and therefore before they set seed – we are preventing them from continuing their lifecycle. It’s definitely a complicated conversation.

Another wild one is Queen Anne’s Lace. I love to use the curled-in seed pods as dried filler for wreaths and arrangements. As a member of the carrot family, it makes sense this is a biennial, but I discovered it because I cleared a hedgerow of stems. The following year there were none.

Other plants also reseed like crazy, but that doesn’t make them biennials. Larkspur is an annual that requires a period of vernalization, but it has a single season lifecycle. Echinacea plants burn out and many specialty varieties revert to purple eventually, so their natural reseeding tendency keeps them going in the garden.

Crop planning for June blooms for June a year from now results in reliable stems valuable to florists, spring event designers and bouquet programs. The last thing I want to do in June is keep more plants alive in the greenhouse, but structuring your seed sowing program to accommodate these is well worth it a year from now.