Ask the Gardener: This bittersweet ending is long overdue

Tips for ridding your property of invasive vines. Plus, what to do in your garden this month.

Bittersweet berries. The bright orange coating, called an aril, appears in autumn and attracts birds, which feed on the berries.Garry Kessler

What to do this month Fall is a busy and beautiful time to work outdoors in the garden. Plant spring-flowering bulbs between now and when the ground freezes in December. I order mine from the wholesale company vanengelen.com and their retail wing, johnscheepers.com, which handles smaller orders. I try to piggyback fall bulb planting with perennial division and transplanting to reduce the number of holes I have to dig. I also try to include three layers of bulbs in each planting hole, with the largest layered at the bottom, pointy end up, and the smallest layer, such as tiny crocuses, only 3 inches under the surface. Bring houseplants back indoors on a relatively warm day now so they are not shocked by the temperature difference. Pull out spent vegetables and seed the empty rows with fast-growing lettuces. When there is a threat of frost, go outside with a flashlight and cut cold-sensitive flowers like dahlias and ripe vegetables such as corn, snap beans, tomatoes, and summer squash. Pick and ripen pink tomatoes indoors. It’s a good time for your lawn’s annual fertilization. Over-seed problem areas and keep them moist until the seeds sprout. Don’t compost weed seeds or diseased foliage, such as mildewed phlox. Do reserve a separate corner to compost a leaf pile, which will transform into nutritious weed-free mulch after about a year.

Q. I recently found several tendrils of Oriental bittersweet wrapped around my hydrangea bushes. I can’t get to the roots because they are intertwined with the hydrangeas’, so I cut them back as close to the ground as possible. Is there anything else I can do?

L.G., Marblehead

A. I believe that you can successfully pull out the roots of bittersweet only when the vines are less than two years old. After that, the roots just break off in the soil. What I do with older vines is cut them back to about a foot and then stick the fresh-cut end that is still attached to the roots into a bottle of systemic weed killer for a few seconds. If the cut is less than a minute old and still raw and moist, it will absorb the liquid poison and transmit it to the roots of the bittersweet internally without harming the surrounding plants, such as your hydrangeas. I also pull small bittersweet vines when they are still young enough to weed. It is surprisingly easy to teach yourself to recognize them by their spear-shaped, pointed leaves and snake-like stems. The roots will be bright orange, letting you know you got the right plant. If the roots you pull turn out to be brown, just learn from your mistake! It’s like taking a plant recognition course in your own garden with instant feedback.

Birds eat oriental bittersweet berries, which helps spread this invasive vine.Adobe Stock/博文 吉永 - stock.adobe.com

Unfortunately, by the time the vines are old enough to produce their easily recognizable orange and yellow berries, they are too old to pull out. But at the very least, I sever stems at the base before they produce berries that attract birds to spread the scourge. The vines can kill trees, but don’t pull down the severed stems, which would increase the damage to the tree. The dead vines will dry and fall on their own. The same is true of porcelain berry, a newer invasive vine with small, pale blue berries — another bad actor that wants to take over your yard. It is related to wild grapes, but the inside of the stem is white instead of brown. It is very, very aggressive. As I wrote last month, there are very few desirable vines other than clematis, so when in doubt, pull it out.

Q. Moss has invaded my flowerbeds like never before in the 40-plus years I’ve lived in my house. What can I do to help the plants that are being adversely affected?

J.C., Watertown

A. Readers are complaining about moss growing in gardens and even on roofs. This is probably due to the record amount of rain we’ve had. Even if you do nothing, I think the problem will resolve itself when we get another swing in the weather pattern, probably next year. If you have automatic irrigation, of course, you should turn it off during rainy spells because moss loves waterlogged soils. It indicates nutrition-starved acid soil. You can improve your garden for next year by digging out (and composting) the moss, sprinkling a dusting of horticultural calcitic lime where it was growing, and then filling the holes with rich compost. Don’t buy topsoil, which could contain weed seeds, and don’t apply fertilizer because you don’t want to stimulate growth at this time of year, when plants need to prepare for dormancy.

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