I'm a Master Gardner here in North Carolina and this question may be helpful to anyone trying to understand perennial, annual, and biannual seeding. Perennial's are fairly simple..they come back every year and bloom and either split off from the root, bulb, or whatever; or they reseed or a combination of the two.
annual's bloom and go to seed and the parent plant dies all in one season. You can collect cuttings or seeds and reseed the plant the next spring and continue the life cycle in this way.
biannual's take two years to complete a life cycle. The first year they establish their roots and grow foliage preparing for what is usually a wonderful showing of bloom the second year of their life cycle which will also be their last. When they drop these seeds some will germinate and grow right away while some will germinate later in the year and even into the next growing season. After planting biannuals once, you will not need to reseed them the next year to ensure yearly blooms and reseeding because some of the seeds will take longer to germinate which will ensure the yearly reproduction.
I hope this cleared up some of the understanding. ALSO, with clover you will want to give that patch long enough to bloom and go to seed before mowing it down to ensure a good reseeding. Just thought I'd throw that in. I usually allow my clover patches to grow, bloom and go to seed once in the spring and once in the fall because I use it for my chickens which LOVE the clover! as do bees. This will be the first year I've had hives of my own to feed off the clover but in the past I've encouraged forager bees to come to my land to help with polination plus I enjoy watching the girls buzz around the herb gardens and annual borders while inadvertantly ensuring a good harvest in my vegetable garden.
