Growing Concerns 461: Iced branch splinted, skunks grub, rabbits, fertilizer

Most-asked questions in this issue:

Grubs, something digging in lawn
Ice- broken branches, new shrubs from cuttings
Rhododendron care
Butterfly bush cuts
Rabbit control
Dog repellents, dog urine repair
Free fertilizer from thunderstorms

Dear Readers,

Perhaps it's the result of a rare alignment of the planets or too much odd weather -- we've never had so much mail as you're sending this spring. In an effort to keep up, here are brief answers to the most-asked questions:

Skunks, lawn diggers, grubs

Skunks are probably responsible for the half-golf-ball size craters in your lawn but thank the stinkers, rather than holler. Skunks dig to snack on grubs -- immature chafers and beetles, bugs that kill your lawn by grazing away its roots. Grubs are legion this year and weather-stressed, neglected lawns are especially susceptible to these pests.

In spring, grubs are nearly grown and thus very tough to kill. The best treatment now is water, water, water, overseeding and fertilizer. This helps the lawn grow faster than grubs can eat. Well-watered, well-fertilized grass won't show the strain even if it has three or four times as many grubs as turf that's dry and starving.

Too late to fix branches snapped by ice

It's much too late to repair ice-damaged tree and shrub limbs. Prune out the broken wood. Limbs small enough to be splinted in hopes of natural grafting had to be realigned, pinned and stabilized right after the break, before nearby cells dried out.

If ice has essentially destroyed a special plant, you might grow a replacement from a cutting but stop dreaming about sticking the big broken piece into the ground and having it root! Cuttings are made from 6- or 8-inch pieces of tip growth, things small enough to live and grow on only a tiny bit of water. Rootless cuttings have to get by with just what a cut stem can absorb directly, so hundred-leaf broken branches don't have a chance.

Fertilizing rhododendrons, acid loving plants

Improve health of exotics such as rhododendron and azalea before pruning or moving. Begin fertilizing now and continue through July. It's not too much to spray weekly with a dilute, water-soluble, acid-loving plant fertilizer. Aim for the leaves and let the excess drip so both foliage and roots can absorb from the mixture what the roots cannot extract from our alkaline soil. Acidic-reaction mulch such as coffee grounds or cocoa hulls and steady water are also essential for these natives of cool, moist, acid soil.

After a year or so of this extra-acid, always-moist care, a rhododendron or azalea can be treated like any other shrub in our overplanted yards. Prune right after bloom if you don't want to sacrifice any flower. Cut it as hard as you like, even to bare wood. If it's in a place that's become too dry or shady, move it when you can. (It's okay but not ideal to do this when the shrub is blooming). For a full year after a move, be even more attentive to fertilizing, mulching and watering.

Butterfly bush cuts are optional

Don't cut butterfly bush if you don't want to. This winter was so mild that they came through with all limbs alive, rather than dying back to their bases. If you cut them, they'll grow back by bloom time to five feet tall and wide -- smaller for the dwarf 'Nanho' varieties. If you don't cut them, they'll probably be larger and certainly bushier.

We prefer the clean lines and smaller size of a cut-back butterfly bush but you can decide for yourself. Cut just one side of your shrub to the ground, or come to Garden By Janet & Steven sessions such as we offer, free at the Detroit Zoo. There, sometimes, we leave some of our butterfly bushes uncut, in order to display for interested visitors the difference in finished look.

Reader's views and short reports:

Gun better than fencing out rabbits

After trying to fence rabbits out of his vegetable garden last year with the eighteen inch tall barrier described here last week, G.M. of Novi reported, "I watched them climb that fence to get my beans!" It's not the norm but still understandable. Many animals were forced to extremes during last July's drought.

When thirsty, starving bunnies resort to scaling a chicken wire fence, a groundhog-type fence is necessary. That's "L" shaped, too, but the upright portion must be at least three feet tall and the top twelve inches should not be tied to the supports. As a climbing animal scales such a fence, its weight makes the loose section flop outward, dumping the climber back onto the ground.

Hot pepper versus shrub-chewer dog

Hot pepper spray worked to stop shrub-eating retriever reports T.N. of White Lake. "My golden retriever chewed the tips of every new shrub I planted, probably just out of sheer boredom. I got him new chew toys and sprayed the shrubs with the same hot pepper spray that's supposed to deter rabbits and squirrels, and it worked. The dog left the shrubs alone, ignored the toys and chewed the wood siding of my house instead!"

Thunderstorm = free fertilizer

Green thumbs up...

...to thunderstorms. Every lightning bolt changes nitrogen in the air into a water-soluble compound. Raindrops carry this essential, quick-greening fertilizer to our yards and gardens.

Green thumbs down...

...to highly-concentrated nitrogen and other chemicals in dog urine, a liquid so salty it draws water and life right out of plants. Dilution is the solution -- quick follow-up by hose or watering can.

First published 4/27/02, updated 4/7/14