It takes them a while to get going, but biennials will overwhelm you with lots of flowers. They make an important addition to your landscape border. Annuals will complete their life cycle in one season, but biennials will take two seasons. In the first season, the plant works on strengthening its root system, and in the second season it will produce flowers and seeds.
Planting biennial seeds is similar to staggering the planting of sweet corn or radishes in your garden. If you plant seeds every year, you will eventually have a flowing mass of plants at different stages of development. Stay on top of it and you will have blossoms from these strong bloomers every year.
Garden favorites include such biennials as pansies, foxglove, delphinium, mulleins, evening primrose, poppies, sweet William, Canterbury bells, pinks, wallflowers, forget-me-nots, money plant, Queen Anne's Lace, and verbena and hollyhock.
Some vegetables are biennial. Brussels sprouts, beets, cabbage, carrots, celery, lettuce, parsley, and Swiss chard need a season to get the ball rolling.
Towering stalks of hollyhocks are a great back row for your landscape, and the plants will reseed themselves so you can continue that patch of tall blossoms year after year.
But it comes with a price. Japanese beetles and other bugs really love hollyhocks, so you might need to sprinkle them with insecticide. Housekeeping is crucial for hollyhocks. Keep the diseased leaves and flowers picked up so they don't spread disease to other parts of the plant. Fungicides help, but can't combat everything. They are also really susceptible to anthracnose diseases.
Many biennials are prolific seed droppers. They do that as a way to survive over many seasons. Foxglove is one of those super seeders. This is the signature flower for any cottage garden, and if you keep sprinkling the seeds around your flower bed and leave the lush fertile loam alone, the plant will continue to reseed each year.
On the downside, foxglove has a reputation for being poisonous. Just touching the plant can cause nausea, rashes, and headaches in some people. Japanese beetles love them and will swarm them in late summer, and they are also very weak when it comes to fighting off anthracnose, leaf spot, and root rot.
Another spectacular biennial is the delphinium. Its tall blue spikes really make a statement in your garden if you plant them en masse. Some varieties can grow six feet tall or more; looks like you will need to dig out your garden stakes for this bloomer.
Cut the old growth back as soon as it dies off. That will tell the new growth that it is time to get going.
Slugs are on the list of pests that like to feed on delphinium. Fungus and root rot can also be a problem. Delphiniums will drop seeds each year, but you might not get the same variety each year. It all depends on where the bee got the pollen. They are heavy bloomers and heavy feeders, so you will need to add fertilizer and stakes to your list the next time you go to the home and garden store.