Category: Outdoors

Wild parsnips burn and buttercups run rampant

This is the time of year when wild parsnips are in full bloom. They stand anywhere from 2 to 6 feet tall and are topped with clusters of tiny flowers facing upward and arranged in a flat cluster called an umbel. The blossoms are similar to those on Queen Anne’s lace, but yellow.

Avoid wild parsnips because you can get terrible burns from the sap of this plant. When the sap on you is hit by bright sunshine, most people develop painful blisters. This is unfortunate, as this common plant is spread by seed, often creating large patches in fields and along roadsides. If you get sap on you, wash it off with soap and water immediately, cover the area, and stay out of direct sunshine for 48 hours.

How can you get rid of wild parsnips? Wild parsnips are biennials, meaning they die after blooming in their second year. I’ve read that mowing a patch of them right after they bloom (but before they produce seeds) will get rid of them, but only if you do this for three to five years. Presumably the repeated mowing is needed to kill plants that come back from seeds that did not germinate in Year 1.

Giant hogweed (Heracleum mantegazzianum) is in the same family as parsnips but is bigger, harder to get rid of and even more toxic. I saw it for sale some 20 years ago and was intrigued by its size (6 to 12 feet tall) and blossoms that are up to 3 feet across. I bought it and planted it, having been told that it was not a perennial, though it is.

Even though I didn’t know its sap could cause burns, I quickly decided that giant hogweed was not a plant I wanted. It popped up 50 feet away from where I planted it, and could grow in full sun or full shade, wet soil or dry. I decided it had potential to take over.

At first I just cut off the flower heads before they produced seeds, but in Year 2 or 3 I decided to pull it by the roots. I was lucky that I was able to get out the roots, which can go down 2 feet or more. And even more fortunately, either I did not get sap on me or I am not allergic to it. It is not widely distributed in New England, though it is a real pest in parts of California and elsewhere.

I was less fortunate when it came to getting rid of the Japanese butterbur (Petasites japonicus) I purchased long ago. I was told that yes, it could run, but it was easy to contain with a lawnmower or a stream. Not so. This plant can send roots 20 feet or more, then send up new plants. It is an aggressive plant that will smother almost any other. It likes moisture, and does well in shade as well as sun.

Depending on the variety, this plant can produce clumps of huge leaves that stand up to five feet tall. It has small flowers that erupt from the soil before the leaves. The roots go down deep and break easily, making it tough to remove. In its native Japan it is considered an edible, but I have no interest in eating it.

I have lost control of our Japanese butterbur. It crossed the stream and has gone under the lawn to other beds, and generally become a pest. Even though it is interesting to look at, enough is enough! I wish I had never bought it!

Another pest I have will surprise you, perhaps: buttercups (Ranunculus repens). Like some of the others mentioned above, at first I welcomed this bright harbinger of spring that displays cheerful yellow blossoms. But it has become a problem because it spreads not only by root but by seed, and once established it is difficult to weed out. And it will choke out other plants. It is glorious in bloom, but very tenacious. If you have moist, rich soil in part shade, watch out. I’d advise removing it early before it starts crowding out other plants. This one is native to Europe, but there are native species that are not a problem, I am told.

Years ago a friend gave me some iris that had the roots of goutweed (Aegopodium podagraria) tangled in with the iris roots. It quickly took over the iris bed, choking out everything else. A native of Asia and parts of Europe, it can form a dense mat that outcompetes everything else. The roots are brittle, and thus hard to remove. Even a scrap of root can start a new plant.

I dug out all the goutweed, took away the soil down to 12 inches and replaced the soil after putting down a heavy weed mat. Still, five years later it crawled out from under the mat. If you have it, accept you will probably always have it, though with persistence and a good weeding tool, it is possible to control. But I wouldn’t buy a house that has it!

A variegated form of goutweed called “Snow on the Mountains” has green and white leaves and was sold as a groundcover in the past. But sometimes it reverts back to the more aggressive all-green form and tries to take over the world. So avoid both forms.

Let’s face it: Plants take advantage of us if they can. We like good-looking, interesting plants, so they put on a good show. But among the good ones, there are those aggressive thugs that deserve no mercy. All you can do is be attentive and act quickly when a new plant starts to take over your gardens.

Featured photo: Goutweed will outcompete any other plants and is difficult to eradicate

Early and carefully

By Henry Homeyer

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I remember talking to a gardener some years ago who, when I mentioned that her tall pines were interrupting the view, waved a hand and said, dismissively, “Oh, yes, I’ll have someone move them.” I nearly choked. Moving shrubs is not difficult, but big trees? Though theoretically possible using a big machine called a tree spade, it’s a very expensive proposition.

I have moved several shrubs over the years. I bought a Carolina allspice or sweetshrub (Calycanthus floridus) which, according to the literature, can be planted in full sun or part shade. I planted it in full sun in rich, moist soil. The first year the leaves got sunburned and developed brown edges. Oh well, I thought, perhaps it had been grown in deep shade. If so, it will recover and next year it will be fine. But the next year it burned again.

So that fall I moved my shrub to a shady place that got just a little dappled sunshine. It did not burn, but it didn’t flower much the year or the year after. “Huh,” I thought. “Maybe it needs more sun.” I waited a few more years, and never got many blossoms.

Finally, like Goldilocks of Three Bears fame, I found just the right place. I moved it into dappled shade under a big pear tree. It has flowered magnificently ever since. Which shows, I suppose, that persistence is important in the gardening world. I was tempted to let it just muddle along, but was rewarded for my effort moving it.

It is much easier to move a shrub in the first year or two of its life in your garden. It takes a few years for roots to grow out and away from the root ball. Early in its life in your garden you will be able to see its original root ball when you dig it out.

When I plant a tree or shrub I generally facilitate root expansion in two ways. First, I dig a wide hole for the root ball, at least three times as wide as the root ball. If the soil is very compacted, I dig an even wider hole. All that digging is intended to leave the soil fluffier, and easier for tiny roots to penetrate.

Secondly, I loosen the roots, tugging them away from the root ball. I pull away any encircling roots. I use my CobraHead weeder to tug on bigger roots that are firmly tangled to get them loose and ready to spread out into the soil. And if I break some smaller roots? I don’t worry. It will stimulate the roots to grow.

The hole should only be as deep as the root ball, not deeper. Your tree should sit on un-excavated soil so that it will not settle in time. If soil or mulch covers the trunk flare, the trunk will rot. It is a slow process, but soil and bark mulch have fungi that will destroy the bark of a tree, slowly killing it — it takes six to 10 years.

What is the trunk flare? That is the area at the base of the tree that flares out and often sends out above-ground roots that gently descend into the soil. It is most obvious in large trees, but some swelling in small trees should be evident at the base of the tree. That area is often buried with soil when you buy a tree, and you need to expose it.

If the flare is buried after planting, you may notice tip die-back at the top of the tree, and early fall coloring. Both are signs of trouble. Check out trees you have planted, and pull back the mulch or soil that is covering the flare. Do it now, and your tree may recover (depending on how long the flare has been buried).

If you are planting trees this summer, remove the tree from its pot or burlap covering. Expose the trunk flare before you dig the hole so you will know how deep to dig. I put a rake handle or wood stake over the hole to help me measure how deep it is before placing the tree into the hole. It is better to have the hole a little shallow than a little too deep. You can always mound the soil to bring it up to the proper amount of coverage.

For moving shrubs, the best tool to use is a long narrow shovel called a drain spade. The blade on mine is about 6 inches wide and 15 inches long. I push the blade into the soil in four places around the shrub. Each time the blade goes into the soil at about a 45-degree angle, with the idea of getting under the center of the shrub itself. I push down on the handle, and it lifts the shrub a little. After loosening the shrub I push down hard on the shovel and the shrub is ready to lift out.

The best time to move a shrub is in the afternoon of a drizzly or cloudy day, not on a hot, sunny day. Move the shrub right into a prepared hole at its new home. I generally do not add fertilizer to the new hole as I don’t want to force rapid new growth. Slow-release organic fertilizer is safe to use, but not too much, and a little compost is good, too.

Be sure to press the shrub down firmly in the hole after you have filled in the space around the root ball with soil, and to pack the soil in around it firmly with your hands. Water well at planting time, and at least every other day during hot, sunny times.

Lastly, I recommend looking at where other people have planted shrubs of the same species as yours that are doing better. And if you need to move yours to a better location? Go for it!

Featured photo: This drain spade is good for transplanting perennials and shrubs. Photo courtesy of Henry Homeyer.