Aggressive perennials can overwhelm garden

Q: Goatsbeard. It sounded like such an interesting plant when my neighbor offered it to me. Now I wish I’d learned about it first. It’s all over the place and I can’t get rid of it. It spreads by clumping out vigorously from the base. It has beautiful white flowers and “fills in” the perennial border quickly, but it has overtaken many weaker plants. Will you please caution me and other readers about this and other plants that aggressively spread in the garden? A.G., Mount Desert Island

A: When one thinks of aggressive perennials such as goatsbeard (botanically called Aruncus) the saying “one man’s flower is another man’s weed” comes to mind. While rapidly spreading plants may indeed become a nuisance in the tidy perennial border, these fast-growing groundcovers may serve a purpose in another setting. A quick-to-establish planting may be desirable, for example, on a bare, steep embankment, where vegetation is necessary to curb the destruction of erosion.

That said, a number of fast-growing perennials should be avoided if the gardener wishes to keep the flower bed in some semblance of order. In general, the entire mint family is what most gardeners would consider aggressive-invasive, although many would also note their practical and beneficial uses are worthy of their tyranny over the less rugged garden species they dwell among. Mints include, but are not limited to, spearmint, peppermint, beebalm, wild bergamot and lemon balm.

Also, the Artemisias are rapid-growing groundcovers. This includes ‘Silver King’ and ‘Silver Queen,’ wormwood and Roman wormwood. Evening primrose, bishop’s goutweed, tansy, ajuga, horseradish, lamb’s ear and comfrey also quickly overtake other plants.

This list is by no means a complete reference for plants to avoid if one wishes to keep the perennial garden in check. In fact, it is a partial listing of plants that reproduce aggressively from the root, spreading and clumping among other garden plants. Yet to be listed are plants that propagate aggressively by seed, dispersing in wanted and unwanted areas alike. This would be an extensive listing.

To avoid creating an undesirable situation in the garden, it is advisable to learn about the life cycle of individual plants – that is, how they grow and reproduce under ordinary garden conditions – before introducing them into the landscape around the home. It is also advisable to obtain a copy of the University of Maine Cooperative Extension’s listing of native plants to avoid using in the garden and landscape. To obtain a copy, call your local Extension office.

Q: During the last windstorm we experienced, a lot of trees in my yard were damaged. There are “hangers” dangling from a lot of the old maples. Some I can reach with a pole saw; others are too high. Do you think I should prune these out or wait until next spring, when the tree is actively growing? D.W., Mars Hill

A: Pruning trees can be dangerous work. It is necessary to have proper safety equipment – especially when using power equipment – when undertaking precarious pruning on mature trees. For pruning away those dangerous and out-of-reach “hangers,” don’t hesitate to hire a professional tree service. It takes care, training and experience to properly and safely deal with damaged trees.

That said, acting within your own abilities and reach, winter is a good time to prune away damaged plant material. When trees are damaged by the wind, breakage typically involves torn and mangled limbs that are prone to rotting over time. The clean cut of a saw will help the tree heal quickly and will reduce the chance of future damage at the wound site.

Where branches are broken and hanging, first cut though torn tissue at the wound site in an effort to release the injured branch and to prevent further “tearing” of remaining healthy tissue. Next, make a clean cut at the node – the point at which the branch is connected to the tree. It is not necessary to “paint” the wound with a compound. Trees have what it takes to heal well if they are properly pruned.

Q: Heavy rains last week and freezing temperatures this week left huge pools of ice in the low spots in my garden. Is this bad for the plants growing there? What can or should I do about this? M.L., Washington

A: Generally speaking, yes, it is bad for the plants growing there. However, it is largely unavoidable, since the rains came after the ground was frozen and water unable to drain through the force of gravity was caught in low areas and left to freeze. Water can be a destructive force and winter damage to plants may be a result of the freezing and thawing of water and the expanding and contracting that occurs in that process.

Unfortunately, there is little one can do during these winter months where water is concerned. This sight at least gives you an opportunity to define these “low spots.” Make a map of them and take note that these areas may be candidates for additional soil amendments or raised beds, come spring.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, 512 North Ridge Road, Montville 04941 or e-mail dianagc@midcoast.com. Selected questions will be answered in future columns. Include name, address and telephone number.