Tag: shrubs

boxwood basil

Two-for-One Plant: Boxwood Basil

Once you recognize the boxwood shrub, you’ll see them everywhere. In most neighborhoods, they are more ubiquitous than speed bumps. But what if I told you the boxwood basil has the same aesthetic as the sought-after boxwood shrub, but it pulls double-duty by also being pesto-ready at any moment. And like the traditional boxwood, this basil is beautiful for edging your garden or shaping into a topiary. I bet you never thought your basil could also look like a bunny.

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Evergreen Hedge Pruning

I have an evergreen hedge that runs the length of my property. It is beginning to grow too large. When and how should I prune it?

Things really begin to pick up in the garden in late winter and early spring, so to stay ahead of the workload, it is a good idea to get as many of the big projects out of the way as soon as possible, like pruning evergreen hedges.

The first thing you’ll want to do is start with a pair of sharp shears so that when you prune the plant you don’t leave any ragged edges on the stems. The great thing about pruning evergreens is that the more you prune them, the thicker they become.

How you make the cut depends on whether the hedge is a broad-leafed evergreen like boxwood or a needle type evergreen, such as Leyland cypress.

Broad-leafed evergreens have dormant buds on their stems down close to the trunk. So when you cut back a broad-leafed evergreen, the dormant buds are activated.

However, you never want to cut a needle type evergreen all the way back to the trunk or to a bare stem because they can’t recover. All of their dormant buds are in the green foliage.

One of the reasons it is wise to prune this time of year is that it’s just before the plant flushes new growth, so you are helping the plant be more efficient with its energy.

Now when pruning hedges, shear them on a slight bevel so that the bottom sticks out a little further than the top. Allowing the top to grow out too much shades out all of the light and causes the bottom of the hedge to become leggy. You can make the job easier by using a string and a line level as a guide to keep it even across the top.

By shaping up your hedges and not let them get out of control, you’ll find it doesn’t take much time to keep them looking great.

February Bloom: Camellia Japonica

One of the showiest blooms in a Southern garden makes its appearance in late February when everything else is still asleep. It’s the Camellia japonica, cousin to the autumn flowering Camellia sasanqua. While sasanquas tend to be delicate, Camellia japonica is a bold, fleshy flower that screams, “Look at me!”

With their dark, evergreen leaves Camellias make beautiful hedges and the blooms create a seasonal focal point.

Camellia sasanquas in Bloom

Patience has paid off and after a year of waiting, the Camellia sasanqua ‘Maiden’s Blush’ shrubs that I planted last fall are in bloom! The 8 foot tall hedge is lightly festooned with pale pink, single petaled flowers. Judging by all the buds yet to bloom, it promises to be a lovely sight over the next few weeks.

Camellia sasanqua is one of my favorite shrubs. In spite of its delicate reputation it is a real workhorse in the garden. Its glossy, dark green leaves persist throughout the year, making it an ideal backdrop plant until fall, when it takes center stage, transforming into an eye-catching focal point as the flowers appear.

Not too long ago it would have been rare to see camellias north of the state of Virginia. But thanks to the efforts of Dr. William Ackerman and the National Arboretum, gardeners in the North can also appreciate the beauty of this Southern belle.

Allen Clipping Camellia Blooms
The camellias Dr. Ackerman developed can take temperatures down to -10 degrees F, which is a huge improvement over the minimum low of 10 degrees F that most Camellia sasanquas can endure. In fact, some varieties of the Ackerman hybrids can even grow in zone 5, which can experience temperatures of -15 to -20 degrees! For the greatest cold tolerance Dr. Ackerman recommends ‘Winter’s Rose’, ‘Winter’s Beauty’ and ‘Winter’s Waterlily’. Like Camellia sasanqua, these varieties also bloom in the fall.

Camellia Maiden's BlushTo further ensure a successful experience when growing camellias in colder climates, plant them in a sheltered area that receives bright but filtered light. They prefer naturally acidic soils, but you can also apply fertilizer developed especially for camellias. A 3 to 4 inch layer of mulch will help keep the roots from freezing, just be sure to keep the mulch away from the trunk of the shrub.

Now if you live in the Deep South, you don’t have to feel left out because Dr. Ackerman has been working on heat tolerant camellias as well! Try the varieties ‘Sun Worshiper’ or ‘Two Marthas’ in your region.

Here is a short list of cold hardy camellias.

  • Camellia ‘Polar Ice’ – white blooms, anemone form, bloom time Nov.-Dec., slow to moderate growing, 6′ tall.
  • Camellia ‘Snow Flurry’ – white blooms, peony form, bloom time Oct.-Nov., moderately vigorous, 7′ tall.
  • Camellia ‘Winter’s Charm’ – lavender-pink blooms, peony form, bloom time Oct.-Nov., vigorous upright growing, 10′ tall.
  • Camellia ‘Winter’s Interlude’ – pink blooms, small anemone form, bloom time Nov.-Dec., moderate growth, 8′ tall.
  • Camellia ‘Winter’s Rose’ – shell pink blooms, formal double form, bloom time Oct.-Nov., slow growing, 6 1/2′ tall.
  • Camellia ‘Winter’s Star’ – lavender-pinks blooms, single form, bloom time Oct.-Nov., moderate growth, 8′ tall.


How to Prune Hydrangeas

I have searched the Internet on the topic of trimming hydrangeas and am still a little confused. My plants are huge and I want to cut them back, but not lose the flowers this summer.

How you prune your hydrangeas depends on what type you have. The old-fashioned pompon variety (Hydrangea macrophylla) blooms on previous year’s growth, or what is referred to as old wood, while Hydrangea paniculata and Hydrangea arborescens set flowers on the current year’s growth.

Let me start with the old-fashioned type as they are the most popular. Also included in this group are lacecaps and oakleafs (H. quercifolia). Little pruning is required with these hydrangeas. In fact, improperly pruned bushes can result in bushes not producing any blooms. In late winter you can tidy up the plant by removing old flower heads and cutting back any dead wood to ground level. Now if you live in a region that experiences topsy-turvy springs with warm spells and cold snaps, wait to prune until after the last frost date. As you prune, cut the faded blooms back to the first set of leaves or leaf buds. If you have a mature shrub that has grown dense in the center, it is a good idea to remove about 1/3 of the oldest stems. This may sacrifice some of the coming summer’s blooms, but it will open the plant up to light and circulation, making it a happier and healthier plant.

Things get a little trickier when it comes to reducing the size of the plant. You have two options. The first option is to cut the plant back in late winter. This will mean that the hydrangea won’t bloom until next year, but I find it much easier to prune at this time because the bones of the shrub are more visible. Simply cut mature stems back by about 1/3. If the plant is completely out of control, cut all the stems back to about 1 1/2 feet tall. Over the course of the summer thin out the new shoots to avoid overcrowding.

The second option is to prune your old-fashioned hydrangea immediately after the flowers fade in the summer. The timing on this is important because the plant needs enough time for the new shoots to harden off before the first frost in fall. For this type of summer pruning, reduce the unwanted height by about 1/3.

Pruning H. paniculata and H. arborescens is a much less complicated task because they bloom on new wood.

‘PeeGee’ is a popular variety of H. paniculata. It produces large cone shaped, creamy white blooms that fade to a nice coppery pink in the fall. ‘PeeGee’ is often grown in a tree form or what is referred to as a standard. This is a single stalk with growth weeping from the top. In late winter cut the stems back to two buds above the base of the stems.

I grow H. arborescens ‘Annabelle’ in my garden. It produces huge, white, pompon shaped blooms in late summer. ‘Annabelle’ is a good choice for people living in both cold regions and warm climates. It is less finicky than H. macrophylla, which is only hardy to zone 5 and also doesn’t do well in areas that don’t experience a dormant season. In late winter I simply cut the plant back to varying heights of 1 to 3 feet from the ground. This will help the plant to maintain its informal shape.

Why Isn’t My Wisteria Blooming?

I have a wisteria that drives me crazy! It is five years old and has never produced a flower. I have trimmed, fed, talked to and even sang for this seemingly ungrateful plant and still it refuses to bloom! Can you help?

I can understand your frustration. I have received many emails from gardeners in a similar situation. Unfortunately, sometimes it takes wisteria an inordinately long period to bloom. Plants grown from seed often have long ‘juvenile’ periods before their first bloom. To avoid this start with plants that have been grafted or started from a cutting. Improper pruning or pruning in the winter or spring will prevent blooms.

Now here is the good news – there are a few things that you can do to promote flower production.

The first thing you want to check is where you have your wisteria planted. Is it in sun or shade? Wisterias require full sun. The more sunshine you give them, the better they will perform.

Wisterias also appreciate a good feeding. In early spring apply superphosphate. Just follow the directions on the label and put it around the base of the plant. This is pure phosphorus, which is the element that helps plants produce lots of blooms and fruit.

And finally, keep all the small tendrils pruned back throughout the summer. This will take constant attention, but it is worth the effort.

As a last resort, root prune the plants by cutting the roots with a sharp shovel. Do this in late spring or early summer. Make cuts at three or four places, about twenty-four to thirty inches from the base of the plant.

Good luck. I hope this helps you see some flowers soon. Although frustrating at times, I have to say, there is nothing like a wisteria vine in full bloom. When it happens, I think you’ll feel it was worth the wait.

How to Create a Windbreak in a Small Space

Years ago rural homeowners were encouraged to plant windbreaks on the north and west sides of their home to save energy and create wildlife habitat. I don’t have the space to plant double rows of large evergreens. Are there some other ways I can get some protection and still provide the wildlife benefits?

It’s true that by incorporating certain design elements into your landscape design, you can help control the comfort level and energy efficiency of your indoor and outdoor living areas. Windbreaks are a practice that have been in use for quite some time and as we all feel the need to do our part to save energy, they are still quite beneficial.

I love the idea of a windbreak pulling double duty by using plants that offer food and shelter for wildlife. Not only are you helping the birds and other animals in your area, but you will find that such a spot in your garden will offer many hours of enjoyment that’s more entertaining than watching TV.

There are several alternatives for those who do not have the space for traditional double row windbreaks. A single row of evergreen trees installed on the northwest side of your home provides some benefit. When there is room for only one row of trees, try to pick ones that retain their lower branches and are suitable for your climate. However, if they do thin out near the ground as they mature, you can combine them with a row of low growing, spreading evergreen shrubs to fill in the bare spots.

Red and white cedars, hemlocks, junipers and spruce all have different varieties and cultivars in various heights, widths and growth habits and could be arranged to fit into the smaller landscape and provide the shelter needed by wildlife.

Large evergreen shrubs can be used closer to the home for winter protection and to direct cooling breezes in summer. They serve to reduce wind velocities and redirect the air flow. This is more practical for small areas and subdivision lots where space does not allow the use of conventional windbreaks. They should be planted close enough to form a solid wall and far enough away from the house (about 4 to 5 feet minimum) to create a dead air space. This relatively still air has much more insulating power than moving air, and can help reduce the loss of heat through the walls.

Large shrubs used as foundation plantings also protect the home from winter winds and summer heat.

Nesting boxes, feeders and watering sites can be added to these plants to improve the habitat for wildlife.

Plants can help reduce energy consumption year round. Vines, shrubs and certain trees can be used as espaliers (plants trained to grow flat against walls) provides foliage cover that insulates your home’s walls against summer heat and winter winds. And, once again, careful selection of plants that have berries and protective branches can provide food and habitat for wildlife and create diversity. Plants that flower and bear fruit at different times of the year are particularly beneficial. Some shrubs that produce berries can provide food throughout the year. Trees bearing nuts and fruit can also be used.

A windbreak takes time to establish for it to be effective. For immediate relief from the effects of wind, construct a fence with an open weave pattern (e.g., basket weave). This creates a larger, protected downwind area than a solid fence. Windbreaks should allow some wind penetration. Those composed of living plants naturally allow some of the wind to come through, which makes them more efficient. Impenetrable windbreaks such as solid fences create a partial vacuum on the protected side, reducing their effectiveness.

Spirea ‘Ogon’

March has come in like a lamb this year and all the early spring blooms in my garden love it. One plant in particular that is really outstanding is Spiraea thunbergii ‘Ogon’.

I purchased this spirea based solely on the amazing chartreuse color, willow-like leaves and delicate form. It is such a wonderful companion to so many other plants that I have kept it in a pot so that I can move it around the garden as I see fit. The bright yellow-green foliage held its color throughout the summer and then in fall it turned an equally brilliant blend of salmon-orange.

Spireas in general are carefree, vigorous growers so I knew I was bringing home a workhorse, but I didn’t realize just how wonderful ‘Ogon’ was until now. This plant has been blooming its head off since mid-February! Even a week of below freezing temperatures and sleet hasn’t slowed it down!

If you want to try this shrub in your garden be sure to give full sun to partial shade, good drainage and room to spread – when content it will grow 3 to 4 feet tall and equally as wide!

Winter Protection for Roses in Containers

Q. I found the column on care of winter roses to be very helpful, but I have one other question.  I have a roof garden in Washington DC and have had some beautiful rose topiaries this year.  What should I do to protect them through the winter-they are in pots.
Thank you very much.

A. In zone 6 you should give your rose topiaries in containers extra protection to help them survive the winter.  Severe cold, below 20 degrees Fahrenheit for an extended period of time, as well as freeze and thaw cycles can damage the roots.  After the plant has gone dormant, if you can, move the container into a cool, but sheltered place such as a garage or unheated storage facility.  The idea here is to keep it cold enough to stay dormant.  And be sure to water just enough to keep the soil from drying out.

If moving the plant into a sheltered location is not possible, another option would be to cover the rose.  Build a wire cage slightly taller than the rose and larger than the pot’s diameter. Fill the cage with an insulating material such as straw or mulch.  Wrap or cover the exterior of the cage with a plastic cover to protect from drying, winter winds.  The cage should be anchored to the ground to prevent strong winds from toppling it over.  Check periodically that the container does not dry out.


Rose Hips

Who says the garden is only beautiful when flowers are in bloom? Interesting barks, vibrant berries, dried seedpods and evergreen foliage all add a sparkle to the grays and browns that dominate the landscape during winter.

One of the more interesting sights to emerge as fall transitions into winter are rose hips, the colorful fruit that many varieties of shrub roses produce in the fall.

My ‘White Dawn’ rose produced unusually large hips this year, about the size of a crabapple. They are a bright orange-red and hang in clusters like cherries.

If you cut a rose hip open you will see the tiny rose seeds stored inside. This is the way the wild roses reproduce and distribute themselves. You can also cross pollinate certain roses in your garden and grow their offspring from seeds found in the resulting rose hips.

To have rose hips in your garden in winter it is important to stop deadheading spent flowers on repeat blooming varieties around August. The petals will fall away and the hips will soon begin to develop. Before you know it you will have enough beautiful rose hips for both you and the birds to enjoy!

Here is a list of a few roses that produce hips:

  • Ballerina
  • Frau Karl Druschki
  • Iceberg
  • Mutabilis
  • Old Blush
  • R. banksia lutescens
  • R. blanda (Meadow Rose)
  • R. rugosa
  • R. virginiana (Virginia Rose)
  • Russell’s Cottage
  • Seven Sisters