Q: The photo shows my chrysanthemum this fall. Should it be cut back now that it froze, or leave it until spring to clean it up? This was the second year for it and I was not sure it would survive the winter, but it did! - Bonnie Johnson.
A: Definitely wait until next spring to cut back your beautiful mum, as they’re one of the perennials that have been shown to winter much better with their tops left intact. Then cut back to near ground level just as the new growth is barely breaking the soil surface next spring. That's also the time to dig and divide, if need be.
Facebook Friend Dorothy Nelson from Thief River Falls, Minn., provided the likely identification of the mum cultivar: “I think it’s Mammoth Coral mum, as it looks just like one I have. I’ve had mine for at least 10 years and it’s very winter-hardy.” Thanks, Bonnie, for an inspirational photo, and thanks, Dorothy, for your testimonial about the wonderful Mammoth series of chrysanthemums.
Q: Is there any advantage to dormant seeding bare spots in the lawn before freeze-up, or should I just wait until spring? - D. Johnson, Bismarck, N.D.
A: Dormant seeding means spreading grass seed on prepared soil at the end of the season when the soil is too cold for the seed to germinate. The seed lays dormant over winter, ready to sprout as soon as the soil warms in spring. The University of Minnesota says “Dormant seeding avoids trying to prepare the soil when it is still wet and cold in the spring and can result in a head start of several weeks in getting the grass established.”
Dormant seeding can be an effective way to repair bare spots in the lawn. Rake the areas heavily to expose some soil. Preferably wait to spread the seed until sometime in November right before snow is expected. After spreading the seed, water the areas well so moisture will freeze and hold the seed in place. Dormant seeding is most successful when several inches of snow fall soon after seeding and remain through winter, protecting the seed from birds and wind.
Q: Since replacing our home foundation, we can start the landscaping around our house. Due to less-than-desirable fall weather, we have been unable to move the perennials yet this fall, like peonies, daylilies, hollyhocks, iris, sedum and yellow daisies. Is it too late to transplant? We also have a lilac and potentilla bush to transplant, but think it might be better to wait until early spring for these. - Jane Christiansen, Casselton, N.D.
A: The lilac and potentilla will transplant more successfully next spring, as you mention. Peonies, daylilies and iris are better transplanted in the fall, so the timing is good now for those. (It's a little late, but they'll still be fine.)
Hollyhocks, sedum and yellow daisies would rather be transplanted in spring, just as new growth is barely emerging from ground level. If there’s not a pressing need to get those moved now, then wait until spring. But if you need to get the job finished, hollyhock, sedum and daisies can be transplanted in fall, realizing the slightly increased risk.