, Salem, MA

June 7, 2013

North Shore Gardener: Fast-growing evergreen should survive

North Shore Gardener
Barbara Barger

---- — Q: Help! Have I ruined my Thuja Green Giant? I have cut the main stem a few times, thinking it was the correct thing to do. (Gardening novice.) I did not realize this would slow its fast growth, which is why I wanted this plant to begin with. Will the Thuja continue a fast growth?

A: You have beheaded the fastest growing evergreen in the garden — you had better have a good excuse!!

Give it some extra care this year and next. It may be a bit slower growing, and if you planted it with others, you will certainly notice a sizable difference — but you shouldn’t have to replace it. Let me know how it goes.

Q: I have forsythia that have bloomed in my yard for the past 40 years. This year the very tops of the branches bloomed late, the middle section did nothing, and there are longish branches on the bottom that bloomed. The bushes look like they are wearing a Hawaiian skirt. What might they need to come back and look normal? I hesitate to do anything, but my gut reaction would be to cut them down to the ground to start over. Because they act as a bit of a privacy screen between two yards, it feels like a last resort.

A: This is at least a two-year job since the shrubs are in need of deferred maintenance. Prune right after the forsythia stops blooming. Remove all dead brown stems about 4 inches from the ground. Also clean out any very tall branches that might spoil the new shape. Good luck — and let me know what happens next spring.

Q: When’s the best time to use a dethatcher on the lawn? Is there a time of year when not to use one? I want to rent one as I never have dethatched and it looks a little alarming under all that green.

A: Dethatching is done in the early spring to early summer; the second choice would be to do it in early fall. Because dethatching stresses grass, do it when the grass is growing best, not in the heat of summer or during a drought. Everyone’s got some thatch. It depends on how finely the grass is cut all year, how long it is allowed to grow before cutting, the regularity of raking, and the weight of snow cover on the lawn during winter.

Usually it is not necessary to dethatch every year. Check first — dethatching is hard work. You can check to see whether your lawn needs it by cutting into the sod and seeing how deep a thatch layer exists. Anything more than about a half-inch, and you could use a dethatching.

Dethatching can be done by machine. You can rent a power machine or do it by hand, using a firm rake. Both methods accomplish the same end — they remove the layer of dry, dead vegetation, which, if left to accumulate, will hinder the absorption of water, fertilizer and weed-control chemicals. Without dethatching, weed killers and fertilizers will just run off and never reach the soil and roots. When left in place, thatch also provides a cozy breeding place for bugs and grubs.

To prevent thatch from reoccurring, use a thatching mower, which cuts the grass blades into fine pieces. You can also accomplish this with an ordinary mower by repeated mowing over the cutting area, to chop and re-chop the grass clippings. Also, try mowing more often and at a higher blade setting, and just removing a fraction of the grass blade with each mowing.

After dethatching, do any necessary fertilizing, top-dressing and reseeding, as well as applying weed controls. And remember to water well — but it looks like Mother Nature will do that for you!

Q: My neighbor was discarding some houseplants and gave me several. One of them looks like an amaryllis, but she said it definitely was not, although she didn’t know the plant’s name. She’s had it years. It has tall green leaves — does it ever flower? When? There is nothing now.

A: Aren’t you lucky! It sounds like a clivia. Clivia is a long-living plant that is truly an heirloom, but you must be patient. Grow in a cool porch all winter with very light watering and wait. Early spring is what makes the waiting worthwhile. One day your clivia decides winter is over, usually between March and June, and your clivia will bloom.

That is the day you discover a bright orange flower stalk beginning to emerge from between the dark green leaves. Go back to regular watering and feeding. Stand back and watch. You’ll see why you bother to grow this large, green plant for 11 months of the year for one month of stunning flowers.

The flowers emerge, usually orange with a yellow throat, clustered on a stem a foot or two high. Some years there will be two or, rarely, even three flower stalks. They will last for weeks, and your visitors will “ooh” and “ah” over the plant. The flowers will gradually drop off. You may want to remove the attractive red berries and the seedpod before it forms unless you are going to save seed, because it takes a lot of strength from the plant to produce.

And another year is over for the clivia — just the leaves are left now — but the flowers will be back next year, and the year after. But the clivia remains elegant with just its greenery in a tub on the porch or near the front door, just basking in glory. It seems to know that it is an investment plant, one that will live and get better with age.

This week’s dirt

Are grubs and slugs ruining your planting beds? Place a few slices of cucumber in a small pie tin, and your garden will be free of pests all season long. The chemicals in the cucumber react with the aluminum to give off a scent that is undetectable to humans, but drives garden pests crazy and makes them flee the area.