Monday, December 21, 2009

Evergreens of the Winter Solstice

Evergreens are an important plant to the winter landscape as they provide us with lively (or should I say alive) foliage in this lowest lit, dormant season. It is no wonder why we use them as Christmas trees.

Two Scotch Pines (Pinus sylvestris) centered in this photograph are remnants of a former windbreak of Scotch Pines -- all the rest have died of pine wilt and have been removed. We planted small one-gallon sized Green Giant Arborvitaes (Thuja 'Green Giant') in between the pines and now they are 15 feet tall and spires of green.

Green Giant Arborvitae are a good choice of evergreens in our climate and currently have no major pest or disease issues.

Many evergreens do suffer in our climate and it is difficult to recommend a fail safe variety. The Limber Pine (Pinus flexilis) photographed here in the Perennial Garden is succumbing to dothostoma needle blight -- an affliction that has made us remove most of these trees from the garden.


The Vanderwolf's Pyramid cultivar of Limber Pine so far has been immune to the leaf blight. A healthy example near the Rock & Waterfall trolley stop shows dense, healthy needles.

Eastern White Pines (Pinus strobus) remain one of the best choices for large evergreen trees in our region. They do require good drainage and protection from salt spray off roads to perform their best. They grow huge over time and naturally open up to a very layered appearance when mature. They were once (along with tulip trees) the tallest trees in Eastern North America. The tallest were cut for the Royal Navy's ship masts.
The Japanese White Pine (Pinus parviflora) has also done quite well and remains a much smaller tree as it grows so slowly. This plant in the Perennial Garden will be 20 years old next season.

Blue Spruce (Picea pungens) is an area-wide favorite and also does well as long as it doesn't get too crowded with poor air circulation around it -- such conditions cause cytospora canker which kills the lower or shaded branches. The Blue Spruce depicted is the cultivar 'Foxtail' which is a fast growing, very blue needled variety.
Our "bluest" evergreen at Powell Gardens is still the Blue Ice Cypress (Cupressus glabra 'Blue Ice') but it is supposedly not fully hardy here. Our plant has flourished but we haven't had a hard winter in almost 2 decades now.
Eastern Redcedar (Juniperus virginiana) is our toughest evergreen and the only locally native one! This seedling redcedar came up in the old Scotch pine grove and we are letting it grow to become part of our new windbreak. Many people hate this plant because it is not green in the winter, we feel it is a great color that seems appropriate to our landscape. Something truly green in midwinter must be sick here! It is an alternate host to cedar apple rust that afflicts apples and crabapples but we simply plant rust-resistant apple varieties (there will always be thousands of wild redcedars around!). The native redcedar is a top wildlife friendly plant.
This Southern Magnolia (Magnolia grandiflora) is a local selection and remains one of our truly greenest plants in the winter. Again, we are waiting for a severe winter to truly test how hardy this tree is -- its parent tree in Independence, MO, did survive past severe winters in the late 1970s through the 1980s.

The long needles of the Loblolly Pine (Pinus taeda) also are quite green now but this evergreen is also at home in a more southern climate. This tree is a seedling from trees planted at Powell Gardens several decades ago by the Boy Scouts and appears to be quite hardy though the long needles make it susceptible to ice damage. I should have had a person in this picture for scale, the tree is nearly 20 feet tall.
This morning was the winter solstice so each day from now until the summer solstice in June will be a bit longer than the next. I am glad that half of the dark half of the year is now over! Take some solace in the beautiful evergreens in this season. We trial a wide variety at Powell Gardens and have a marvelous collection of mainly dwarf varieties north of the Visitor Center in our conifer garden.
All photographs taken by Alan Branhagen on the winter solstice at Powell Gardens.

Wednesday, December 16, 2009

Winter Landscape Tips

It is the season to enjoy the beauty of evergreens and other plants with winter interest. Powell Gardens with its 7,000 varieties of permanent plants on display, offers a good place to see a inordinate variety of plants in the landscape.
The evergreen spires are Green Giant Arborvitae (Thuja 'Green Giant') and look rich green and boldly textured.

Backlit in our winter sun, the same grove of Green Giant Arborvitae looks dark and ominous! Evergreen trees including the Green Giant Arborvitaes are best sited in the landscape where they will break the prevailing winter winds. That means planting them north and west of your home, the perfect setting to view them from in winter. They also diminish the wind on your home which can cut heating bills by between 10 and 25%!!! Planting evergreens on the south side of your house means you will see what is depicted here and they will block the wonderful, warming winter sun. The shadows of evergreens can create winter patches of snow and ice that can be a nuisance on walks and driveways.

A very few evergreens look at their best when backlit in the winter. The Inkberry Holly (Ilex glabra) is one such plant that simply sparkles when backlit in the winter sun. Inkberry Holly is a medium to large shrub and makes a wonderful natural winter screen but doesn't get tall enough to block the sun to most home's windows. This shrub is often used as an American native substitute for boxwood but it never stays that dense and opens up into a more free form as it ages. Use boxwood for formal hedging and tidy evergreens, not Inkberry.
Now that we have had two arctic outbreaks, it's nice to stay indoors and look outside at the landscape that surrounds you and think about plant/landscape additions for next spring. Looking out the Horticulture Building's southwest window we see a Kentucky Coffeetree (Gymnocladus dioicus) which is the perfect plant for this location. A shade tree at the southwest corner of your home will help shade your home during the hottest sun of summer. Air temperatures under a shade tree are as much as 18F cooler. Shade trees are 24/7 living air conditioners that also absorb carbon dioxide, dust and other particulates (asthma rates for children fall by a quarter in areas of high tree population) and release oxygen as a biproduct of photosynthesis.
The shadow of the Kentucky Coffeetree on the Horticulture Building also demonstrates why Coffeetree is such a ideal building shade tree. The plant is very open in the winter and allows maximum sunlight to penetrate now -- warming the building! Choose sturdy shade trees with open crowns and coarse root systems that won't invade utilities. Other good examples include Bur, Chinkapin, Post, Northern Red and Shumard Oaks, Baldcypress and Cucumber Magnolia. Bad choices would be Silver Maple, Cottonwood and Sweetgum.
A view out my screened office window shows the Possumhaws (Ilex decidua) cloaked in vibrant red berries. Everyone who comes to visit is immediately drawn to these vibrant trees in the winter landscape. Not only do they provide an invigorating warm color in the landscape now but they attract wildlife that provides drama in the landscape. This is the winter larder of a possesive mockingbird while robins, bluebirds and waxwings will come in to feed on occasion too.
Other deciduous hollies like this grove of Sparkleberry Hollies (Ilex 'Sparkleberry') in the Perennial Garden equal possumhaw for vibrant color in the winter landscape. We did not experience below zero temperatures here so the colors have remained vibrant. Choose Red Sprite Winterberry as the smallest deciduous holly maturing at 5 feet to Winter Red and Sparkleberry which reach about 8 feet in height. Possumhaws eventually become small trees so plan on them reaching 20 feet in height or more over a long period of time. Remember only the female plants have these beautiful berries and an appropriate male cultivar is needed nearby for pollination. Sparkleberry holly requires 'Apollo' or 'Southern Gentleman' holly as a pollinator.
A view across the parking lot to the Maintenance area reveals well placed evergreen shrubs and ornamental grasses. These effectively screen the view at almost all seasons though the grass is cut back in spring but quickly fills in by early summer. The shrubs are Leatherleaf Viburnums (Viburnum x rhitidophylloides) and the grasses are maiden grass (Miscanthus sinensis). Take a look out all your windows now and if there are any unsightly views, plant a screen for them next spring!
A walk through the Powell Gardens perennial garden reveals a great balance of all types of plants from groundcovers to deciduous and evergreen shrubs and trees. A diversity of plant forms and their proper placement really does create a most inviting landscape. Don't experience cabin fever and plan a winter visit to Powell Gardens to observe all the subtle beauty of winter and get ideas that will enrich your home landscape.









Tuesday, December 1, 2009

Meet the Poinsettias of 2009

Tracy Flowers, Gardener Kauffman Memorial Garden (left), picks poinsettias for Gardener Kellyn Register and Senior Gardener Eric Perrette to sleeve and load for a trip to the Kauffman Memorial Garden's holiday display in the conservatory.

Powell Gardens grows all its poinsettias from approximately 3,000 rooted cuttings at our greenhouse complex. They are cared for by loving hands from planting to finishing and public display. We grow 27 varieties and trial some new varieties each year.

Here's a sampling of some of 2009's poinsettias -- photographed in the Powell Gardens Greenhouses on Dec. 1 & 2, 2009:
Poinsettia 'Freedom Red' is the most traditional of varieties with large, red bracts.
Poinsettia 'Premium Red' is another classic red for traditional holiday decor.
Poinsettia 'Freedom Fireworks' has narrowed and elongated bracts more like a fireworks explosion.
The camera can't quite capture the dark burgundy-red of Poinsettia 'Merlot' which is probably my favorite of those we grow.
Poinsettia 'Silver Star' are on their way exclusively to the Kauffman Memorial Garden. The silvered, white-edged leaves and red bracts make it a standout.
Poinsettia 'Jingle Bells' is a fun smattering of pink on red. It often sports unusual pink or white bracts making it a challenge to grow.
Poinsettia 'Freedom Pink' is our best pink with huge bracts.
Poinsettia 'Jester Jingle' adds a bit of fun to a poinsettia display.
Poinsettia 'Ice Punch' inspires the most visitor comments with its silver-pink "icy" variegated bracts.
Poinsettia 'Ice Crystals' is a creamy splashed shimmering pink.
Poinsettia 'Sonora White Glitter' is red with white spangles to the bracts but it has still not "finished" with immature bracts.
Poinsettia 'Marco Polo' has very unique salmon frosted, pink bracts.
Poinsettia 'Premium Miro' is a creamy white with pink-frosted bract edges.
Poinsettia 'Winter Rose Marble' is another sensational poinsettia attracting many comments.
Poinsettia 'Premium White' may be our best white bracted cultivar. It certainly photographed the best of all the whites and the only one I dared show.
Tracy Flowers poses with some Freedom Red Poinsettias to show how wonderful our poinsettia crop is this season. Kudos to Horticulturist Donna Covell and the greenhouse team for their success.
The poinsettias are displayed to all visitors at the Powell Garden's Visitor Center conservatory and at the Kauffman Memorial Garden. Some are even for sale at Powell Gardens' Perennial Gifts (gift shop).