I beat the rain with most of my gardening chores yesterday. I deadheaded and cleaned up some of the dead plants. My Mallows seam to have developed rust ~ it's a fungus, probably due to the amount of rain we've had. Luckily, it showed up at the end of the season instead of earlier. I started collecting seeds from the two plants in the photos. The Black-eyes Susans and the Coral Nymph Salvia. They both produce a ton of seeds. I wanted to give some tips on dividing perennials. Dividing perennials gives you a chance to add plants to other areas of your garden or to share w/ friends. It also keeps the original plant from becoming overgrown and ragged. It's best to divide on a calm day. The wind or sun can dry out the roots. If you don't have a choice: soak the roots and cover w/ moist newspaper until you are ready to plant. Dispose of any woody centers. You'll want to work up your soil w/ compost before planting also. I have a "toss and forget" type of composter ~ it takes longer than the tumbler kind but I only use it in the spring and in the fall so it works for me. If you don't compost, you can purchase a bag of compost (leaf compost is really good) from one of the home/garden stores. When you are actually doing the dividing, you can either dig up the entire plant and either cut or pull apart in sections. The other is to split the plant, leaving half of it in and removing the other half. That half can be divide also. The latter is what I normally do with my Shasta Daisies, Coral Bells, Hostas, but for my Astilbes and Goats beard I usually dig up the entire plant and divide it.
I also read up a little on digging up Dahlias. In Maryland, Dahlias don't make it through the winter so if you want to have them again for the next year, you have to dig them up. The best time to dig them up is after the first frost when the leaves turn brown. Dahlias have tubers which you need to wash off and let air dry for several days. If you want to keep track of what color each one is, you can write directly on the tubers w/ a Sharpie marker. You'll want to store the dry tubers in a box lined w/ a trash bag. Leave the bag open for air circulation and place in a cool dry area that doesn't freeze. (40 - 50 degrees is the best) Occasionally mist w/ water to keep moist. Divide the tubers in the spring. Cut w/ sharp knife. Each section should include the root, part of the crown and at least one growth bud. Let cuts heal for 2 days before planting to avoid root rot. Wait until the ground is warm before planting or start indoors. I'm going to give this a try this year. I'll let you know how it works out!
Have a nice day!