Nothing beats Cosmos bipinnatus when it comes to a quick growing annual. When it comes to this plant, there are several aspects that make it a winner. First, the foliage provides an unexpected textural element to the common color green. The feathery like leaves create a light and airy foreground that is topped with flowers that are three to four inches in diameter. The daisy shaped flowers come in colors that include red, pink, white, and lavender. The brightly colored flower petals are accented with a contrasting yellow center.
While the physical description sounds wonderful, there is one negative aspect to this annual and that is the height. On average, the cosmos reaches a mature height of six feet. This height can be limiting when it comes to using it in your landscape.
When it comes to propagating this annual, you have two choices. It is easily and successful sown outdoors and the seeds germinate fast after your local frost free date but if you want to get the earliest blooms possible, start the seeds indoors.
If you choose the first approach, simply pick a sunny, garden location and prepare the soil. Once your local frost free date has passed, broadcast the seeds over the soil surface, and mist with water. These seeds require light to germinate so do not cover with soil. In three to seven days, the seeds will have germinated. Once the seedlings are large enough to handle, thin them so that they are spaced 12 inches apart.
Starting your seeds indoors starts off with your calendar. You will need to start your seeds four weeks prior to your local frost free date. Once you have that date, clean and sterilize your pot, fill with moistened soil, and sprinkle the seeds on top. Mist with water and place on a sunny windowsill.
Prior to planting the cosmos in your landscaping, make sure to harden off the plant material two weeks prior to your local frost free date.
Now that you know how to propagate cosmos, what are some ideas for their use? One of favorites is as a covering for something less attractive. What do I mean by this? Well, consider a privacy fence. While I have seen many beautiful privacy fences, they simply tend to be all the same. To add some color and break up the “brown” without having to paint the fence, consider growing cosmos in front of it. Since this plant is only annual, you really are not committed to the plant and if you like it, the plant easily reseeds itself. All in all, saving you work.