Hortiscope: Hollyhocks in our zone may live again if cut
Q: I have a very large basswood tree in my backyard. In mid-July, it starts dropping an incredible amount of thin, long, light-brown leaves and small, hard, tan-brown berries. Is this typical of this tree and how long should I expect it to last?
A: All of what you describe is normal for the basswood or linden. The brown leaves are really bracts from the base of the flowers/nutlets that the tree produces every year. It will stop dropping some time this month, but it depends on where you live. My own linden is doing the same thing. It is a small price to pay for such a majestic tree that has fragrant blossoms growing when nothing else is making a significant showing.
Q: We have a row of caraganas that were nice and green until mid-July. At that time, the leaves started to wilt and turn yellow. The leaves have since curled up, turned brown and fallen off. The tops of the branches are black. Most of the tree row is leafless in sections with spotted sections of green. We thought someone had sprayed the area with Roundup (we have reason to believe someone would do that), but someone said Roundup wouldn't do that. Some of the trunks are still green. However, most of the branches from the bottom up are bare and brown and look dead. For a while, it stopped, but it has started again. We live in Saskatchewan and have had a wet and cool spring. Last year we had a really wet and warm spring and summer. Should we cut them down? Do you know what is causing it?
A: Since the cambial tissue is still green, I would suggest that sometime between now and permanent freeze-up, you cut the caraganas down to just above the ground and remove all the cuttings. Burn the cuttings if possible. If they are going to recover, they should next spring with a flush of new growth. If not, then you've taken the first step toward getting them out of the ground.
Q: I planted a hollyhock alcea rosea that is blooming. It is listed as a biennial. Does this mean it will bloom every other year? Will it grow but not bloom next year? I am confused just what biennial means for the hollyhock. Thank you.
A: The term biennial means that the plant will remain vegetative the first year, then bolt and go into the reproductive (flowering) stage the next year. It then will die. With hollyhocks that are biennials, growers know that customers do not want to wait until next year for it to flower, so they treat the plants with a hormone or put it through an artificial cold period. By doing that, the plant either will be in flower or will flower shortly after planting. Depending on your climate, hollyhocks are perennials or biennials. In zones 9 and 10, they are biennials. In zones 3 to 8, they may live through the following winter and bloom again if you cut the faded flower stalks off at the base.
Q: Our lawn is hard to dig through, so I am thinking that the water is not getting down to the roots. Would it help to use an aerator? If so, when would be the best time to do it?
A: Right now would be a very good time to get the aeration done. Water the area 24 hours ahead of time or aerate within a day or two after a good rain. Then overseed and fertilize and your lawn should shape up nicely.
To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or e-mail firstname.lastname@example.org.