|I had some dahlias that just did not do well this year. I potted them with rocks and straw fibers at the bottom and that probably hampered them. a. Do they still look ok from a root perspective? I have dug them up to store for the winter, should I cut them at the top of the stem, let them dry out and then store? Thanks|
|The tops of the plants look a little leggy - they may not be getting quite enough sunshine. Dahlias thrive in all day sun. 8 hours of direct sunshine is best. I don't think the rocks and straw fibers hurt the plants. In fact, they would have ensured the soil drained quickly. The fat tubers will grow large, healthy, flowering plants; the thinner tubers will grow plants, as well, but since they haven't stored much in the way of carbohydrates, I think the plants will be smaller.
In general, dahlias should be left to grow until frost blackens the leaves and stems. This allows for the longest growing season which translates into more carbohydrate storage in the tubers. Next year leave the plants alone until after your first hard frost.
For now, I'd prune off the stems and leaves, brush off excess soil, and store the tubers for the winter months. You can separate them now or wait until just before replanting in the spring. Enjoy your garden!