Tag Archive | Shrubs

Pruning Rule Breakers

rhododendron-245633_960_720Rhododendrons, unlike most shrubs, have no painless window for pruning. They start forming the buds for next year’s flowers before this year’s have even opened, and by the time bloom season is done, those buds are well advanced.

It’s difficult emotionally to cut off any of next year’s flowers, but if you continually avoid pruning, you may be even more devastated. In fact, you could end up having to cut the rhododendrons to the ground and start all over again.

Pruning rhododendrons requires imagination as well as sharp sheers. Dr. Richard Lighty, the director of the Mount Cuba Center for the Study of Piedmont Flora in Greenville, Delaware, advises that you try to visualize what the shrub should look like. Reach your goal by critically selecting strong outer branches that, when pruned back, will expose smaller inner branches in the right position to fill in. Once exposed to light, these inner branches will begin to grow.Rhododendron-pruning-outline-diagram1

As the flowers fade, trim no more than 15 to 20 inches off the strong branches. Where should you prune? Where the strong branch is near the tip of an inner branch that has a whorl of glossy leaves surrounding the buds, your signal that the inner branch is healthy. If the shrubs are still too big, reprune in two years.

To make sure the plant has stored enough food that it can easily handle pruning, fertilize in late fall the year before you intend to prune. If you fertilize after pruning, it will put out long, leggy growth.

Although it is better to stay on top of your regular pruning chores, rhododendrons can be cut down to 12 to 15 inches from the ground if necessary. The plants have buds at their base that will generally send up new shoots. But, as I learned, there won’t be any flowers for two to three years.

Shearing is not Pruning

This time of year, we’re preparing for winter and many folks are doing some Fall pruning. Do you say you’re grabbing your shears

Ficus benjamina (formally sheared)

Ficus benjamina (formally sheared)

or your pruners? There is a difference between pruning and shearing.

Pruning means cutting off a part of a living plant, and covers everything from snipping a twig to reaching deep inside a tree canopy and sawing off a major branch. Shearing is a particular kind of pruning, one in which only branch tips are cut, and they are cut as a group rather than individually.

The goal of shearing is to force lots of small outer branches while creating a smooth outline. The result — if it is successful — is that the sheared plant loses it’s natural identity and becomes a formal shape.

Creating a box hedge topiary by hand

Creating a box hedge topiary by hand

The most common example of the technique is the flat-faced wall of a sheared hedge, but people also shear plants into mounds, pyramids, graduated balls on sticks, or (in a few extreme cases) things like chess pieces and leaping dogs.

Shearing at the simple hedge level seems as thought it should be easy; just hold the shears at the proper angle and clip away. In fact, it takes patience, practice — and strong arms — to see where you need to cut and then do the cutting properly.

Electric hedge trimmers promise to relieve you of much of the work, and they do make it go faster. But they are heavier than hand shears, their speed increases the chance of mistakes, and they have a regrettable tendency to tear everything they touch instead of cutting cleanly.

Fire in the Fields

Sumac lighting up a hill in Wisconsin's autumn

Sumac lighting up a hill in Wisconsin’s autumn

It happens every autumn. Huge sweeps of straggly, undistinguished shrubs that grew unnoticed in unkempt fields are suddenly, gloriously, ornamental. The long almost palmlike fronds of leaves shine bright red with hints of yellow and orange. The branches spread like candelabra holding up huge crimson fruit clusters that keep glowing long after leafdrop, when all the world is gray. No wonder gardeners think about bringing sumac in from the wild.

Staghorn sumac in the summer before changing color

Staghorn sumac in the summer before changing color

Sumac grows everywhere, all the way from zone 2 to zone 9. It grows in dry soil, poor soil, moist soil, near-bog, bright sun, and part shade. It spreads by seed and by underground runners that can travel 20 feet or more in search of a good spot to make a new clump of sumac. But if there is also a lawn anywhere nearby, there will be adequate local control as long as you keep mowing.

Smooth sumac (Rhus glabra) is the most common roadside attraction. It’s fuller and more readily clump-forming than staghorn sumac (R. typhina), named for the velvety down that covers every branch. Smooth sumac tops out at about 8 to 10 feet, staghorn at 12 to 16 feet.

Fragrant sumac makes a beautiful garden addition

Fragrant sumac makes a beautiful garden addition

Fragrant sumac (R. aromatica) is shorter, at 3 to 4 feet, and bushier, more like a garden plant. If you decide to bring sumac into your garden or prairie, no matter which type you choose you will need both male and female plants if you want fruits. Sumacs are available through nurseries that specialize in native plants, and some large garden centers will order them for you if you ask.

Note: it’s always a good idea to check whether a plant is considered an invasive species in your state before transplanting from an area where the plant is growing wild. In Wisconsin, the Department of Natural Resources provides a free guide to invasive species here:  DNR INVASIVE SPECIES GUIDE

 

Lilac Woes

Did you plant a lilac bush and have lovely flowers the first year and nothing since then? Or maybe you’re not getting the flowers that you used to get from your established lilacs?

According to Jack Alexander, the chief plant propagator at the lilac-magnificent Arnold Arboretum at Harvard University, newly planted or transplanted lilacs tend to have transplant sulks. Most spring-flowering shrubs, lilacs included, form flower buds the previous year. That initial display you see when you buy new shrubs was set when the lilac was still comfortably at home in the nursery. When it was moved, the disturbance set it back. Give it a bit more time, and whatever you do, don’t move it again!

flower-356176_960_720Common lilacs (Syringa vulgaris) and the French hybrids based on them are especially sensitive in this regard. If you’re the type who likes to move the furniture around, try planting ‘Miss Kim’ (a cultivar of S. patula). She’s a bit less fussy about an occasional relocation.

‘Miss Kim’ is easy to find at nurseries, as are a good number of S. vulgaris varieties and cultivars. But for the widest selection of colors, fragrance, and bloom times, mail order is the way to go.

Pruning

Lilacs have to grow for a few years before they start flowering. After that, they bloom in spring on year-old wood, the stems that grew from the older branches during the previous summer.

Pruning consists mainly of removing elderly trunks and clipping off seed heads within reach. But if you want to cut back young growth, the proper time is right after flowering. It should be done as soon as possible, and no later than three weeks after petal fall.

Still not getting Flowers?

If you are not pruning too late or cutting off all of the new growth, the problem may be too much fertilizer, which could push vegetative growth at the expense of flowers. Or, maybe the problem is a lack of light. Lilacs need plenty of sun to flower well, and shade is the most common culprit when mature bushes fail to bloom.

Remember, too, that if you go through a summer of little or no rain, the plant will be unable to set buds for next year so you can expect little or no flowering the year after a drought.

Transplanting Peonies

Autumn is the best time to plant peonies, whether they are newly purchased or simply being moved. You can start whenever the weather cools but should stop at least six weeks before the expected date of frozen ground. (Newly planted peonies won’t mind early fall’s icy mornings because the soil below the surface is still warm, but they must have plenty of time to make new roots before growth sops for the winter.)

Start by choosing a location where they can grow undisturbed for the foreseeable future. Peonies are long-haul plants, not at their best until they have been in place for some years.

Test the soil in the planting spot to be sure it has a pH of at least 6, although 6.5 to 7 is better; amend it with dolomitic limestone if necessary. If you’re moving the plant, cut off the discard the spent foliage. Dig up and handle the roots carefully as they are quite brittle.

Peony_zpsce6b6354Dig planting holes roughly twice as deep and wide as the peony roots. Prepare the soil by working in a few shovelsful of compost. Set the roots in the prepared holes, making sure the budlike eyes are no more than 2 inches below the ground. Backfill gently; don’t tamp down around the plants. Water them in, then top off with additional soil if necessary.

After the ground is frozen 3 or 4 inches down, add a protective blanket of straw, shredded leaves, or bark mulch. Do not fertilize until spring, when a generous application of compost will be welcome.

Note: there is an old wive’s tale that says you shouldn’t cut more than a third of your peony blooms or you’ll have fewer flowers the next year. Wrong, wrong, wrong! Plants get nourishment through roots and leaves and use it to make flowers and fruit. The flowers are takers, not givers, as far as the plants resources are concerned, and you could cut every one without hurting the plant at all. In fact, when flowers are removed, perennials can use the strength that would have gone into making seeds to do things like fight disease, put out replacement foliage, and build up their underground resources. 

The one-third business probably got started because peonies have short stems. When you cut them for the vase, you usually take a lot of the foliage, too, and a plant does need its leaves to stay healthy. So, leave the leaves, take the flowers, and don’t forget the “get rid of it” rule: even healthy-looking peonies usually harbor fungus spores that should not stay nearby or be composted. Send all peony flowers to the landfill, bury them a foot deep, or burn them.

peony-bud-111910_960_720And one more thing: don’t attempt to eliminate the ants that crawl all over your peonies!! Peonies have tiny nectaries, specialized tissues that secrete nectar, at the edge of their bud scales (delicate leaf-like structures covering the bud). The nectar is a highly nutritious blend of sugars, proteins, and amino acids and it attracts the ants to the flower buds. In exchange for the nectar, the ants provide protection for the buds. Any bud-eating pest is attacked by the ant who make formidable foes since some of them can bite from one end and sting or spray from the other end. Don’t spray the ants with poisons or water — the peonies know what they need better than you do!

Of course you can grow Roses!

I’ve tried and tried to add roses to my garden. I’ve put them in sun, I’ve put them in shade, I’ve planted them all together, I’ve interspersed them with other plants, I’ve tried hybrids, I’ve tried tea-roses — nothing ever grows properly! Several years ago, I was having moderate success buts, after a hard winter, I went out to find that my rose bushes had been eaten to the ground (thorns and all) by very hungry rabbits.

How can you not want that beautiful color and fragrance, though, so I keep trying! For help, though, I’m now turning to the experts for advice.

One of the most beautiful rose gardens in our region is located in what you might call a difficult rose growing area. The Leif Erickson Public Rose Garden in Duluth, MN is a zone 3 or 4. The rose garden features many different varieties, from species rugosa to hybrid tea roses. Hardy rose hedges line walkways, and a planting of hardy shrub roses near the entrance welcomes the 100,000-plus yearly visitors to the garden.

2504-1271616438ho6hBasic rules for growing roses:

  • Select hardy roses
  • Plant in an area that gets plenty of sun — at least six hours of sunlight a day
  • Make sure you’re planting in soil that provides excellent drainage. Roses don’t like wet feet. [Note: a good planting companion is lavender that also doesn’t like wet feet. Refer to our blog post regarding these garden companions here.)
  • Water regularly, especially during hot summer days. Most experts recommend about 1 inch of water per week. When watering, make sure to soak the base of the plant, keeping water away from the leaves.
  • Feed your roses using an all-purpose slow-release fertilizer, or a fertilizer specially designed for roses. Be sure to follow label directions.
  • Roses can thrive in a large container. Be sure to keep the planter evenly moist and fertilize regularly.

Types of roses:

  • Hybrid Teas: showy, most popular
  • Floribunda: shrubby with bloom clusters
  • Grandiflora: tall, ideal for cut flowers
  • Miniature: only 6 to 18 inches
  • Shrub: large and full; some are fragrant
  • Climbing: use with trellises, arbors and walls

Master Gardener Marilyn Davis teaches the “Roses” portion of our training classes for new Master Gardeners each year, and has created a list of cultivars recommended for Wisconsin:

Rose_yellow2

Knock Out Shrub Rose (yellow)

 

  • Hybrid teas:
    • Strike it Rich (yellow bloom) – 5ft high
    • Miss All American Beauty (hot pink) – 4ft high
  • Floribunda
    • Betty Boop (white/red) – 4ft high
    • Ice Berg (white) – 4ft high
    • Honey Perfume (apricot/yellow) – 4ft high
  • Grandiflora
    • Prima Donna (deep pink) – 4ft high
    • Love ( red blend) – 3ft high
    • New Year (tangerine) – 3 to 4ft high
  • Miniature
    • New Beginning (orange/red) – 2ft high
    • Debut (red/white/cream blend) – 2ft high
  • Shrub
    • Knock Out series (yellow) – 3ft high
    • Parkland series (red/pink) – 2ft high
    • Bonica (pink) – 4ft high
    • Austin English (apricot to crimson) – 4ft high
  • Climbing
    • New Dawn (pink) – 18 to 20 ft.
    • Winner Circle (red) – 18 to 20 ft.
    • Autumn Sunset (yellow double) – 8 to 12 ft.
img_0275

Miss All American Beauty

To keep roses blooming throughout the growing season remove spent flowers (deadheading). This transfers the plant’s energy back into creating stronger roots and even more blooms. Trim down to the first or second five-leaflet leaf.

 

Ice Storm Mitigation

dennis-macdonald-tree-branches-after-an-ice-stormWinter is far from over and it seems like we get at least one or more days of freezing rain in late winter. The freezing rain will cause ice to build up on the branches of trees and shrubs, and you might wonder if there’s anything you can do to help mitigate potential damage in your garden.

Usually, it’s best to just leave everything alone as a coating of ice for a day or two rarely hurts a plant. Branches may sag a bit, but then the ice melts or cracks off and all is well.

If, however, the ice is quite heavy and more ice is due, you can reduce the weight, and therefore the risk of damage, by carefully removing some of the ice. Use a soft broom and gently tap the branches, cracking the ice so it falls off. You don’t have to worry about removing all of it — just enough to lessen the weight on the branches. Be careful not to hit the branches too hard or you may end up damaging the bark or breaking off the buds. Also, use caution with large trees or shrubs so you don’t drop ice or branches on your head!