Monday, December 29, 2008

Wild Weather and Winter Greens

This first month of winter has been true to Kansas City: a manic-depressive wild ride! We have had two days with highs in the 60s, inch rains twice, plus sleet and 2 inches of snow. The predicted "coldest Arctic blast in a decade" did not materialize. Yes, it was cold but not even close to record cold. At our official weather station in a cold pocket the temperature bottomed out at zero, twice (the month of the terrible twos?). There are still two more months of winter to go and March can go either way. The cold weather did no damage to any plants that I can see -- it was nothing out of our "ordinary."

Below are some images of the many wonderfully ornamental plants that really show off at Powell Gardens in the winter. I feel like a broken record pushing the beauty of winter and its ornamental plants -- it is something I always consider while acquiring plants through the year. My how these plants can really shine now, especially when viewed from indoors. I do recommend a new book on winter gardening: The Garden in Winter by Suzy Bales. Suzy (from Long Island, New York) has spoken at Powell Gardens and I had the pleasure to show off our grounds to her pre-Easter freeze in 2007.

American Holly (Ilex opaca) is perhaps the classic winter garden plant and such a symbol of holiday decor. As with all hollies, only female plants produce fruit and most need pollinators nearby (some hybrids produce fruit without pollination). Plant this long-lived, slow but beautiful tree for future generations to enjoy! It is hard to find and generally available only by mailorder in Kansas City. There are magnificent small trees in the 30-40 foot range in the older parts of Kansas City and its older suburbs. This evergreen is native to southeast Missouri and part of Missouri's Grow Native! program.

Greenleaf Holly (Ilex x attenuata 'Greenleaf') is a hybrid between the American Holly and Dahoon (Ilex cassine). Because this holly has hybrid vigor and grows very fast and is easy to propagate it is readily available at nurseries. It has smaller fruits that the birds really relish but is much less hardy then American Holly. It grows more int the 20 - 30 foot range in our area. Be sure to plant it in a sheltered place when outside Kansas City's "heat island." Yes, the core of the city is usually 5 degrees warmer than the surroundings - year round! This plant has completely died back here (2001) but recovered well.

Blue Princess Holly (Ilex x meservae 'Blue Princess') is a beautiful hybrid shrub holly that is very hardy. It is a cross between a cold hardy holly (Ilex rugosa) from Hokkaido(north island), Japan and the beautiful yet non-hardy English Holly (Ilex aquifolium). There are several cultivars in this group but Blue Princess has the best, glossy leaves with a hint of blue. We also have 'Blue Maid' in this group with 'Blue Stallion' as pollinator. This holly does not like extreme heat and the big swings of temperatures we can have here. Our plants killed to the ground one year (2001)but have completely recovered. I found it odd they died back when Southern Magnolias growing above them were uninjured! They are against the north wall of the Visitor Center where they stay cooler and shaded during the hot summer. This hybrid holly is readily available in nurseries and even big box retailers.

China Girl Holly is another hybrid holly using the hardy holly (Ilex rugosa) but it is crossed with the Chinese Holly (Ilex cornuta). This hybrid is much more apple green in leaf and stem as well as inheriting heat-tolerance from the China Holly. We grow these shrubs on the south side of the Visitor Center where it gets very hot in summer. The pollinator is aptly named 'China Boy.'

Acrocona Norway Spruce (Picea abies 'Acrocona') is a personal favorite of "dwarf" conifers. The abundant cones are very ornamental in winter (they are bright magenta in spring when emerging as female flowers!). This pine grows slowly to be at least 8 feet tall and wider than tall.

The flat sprays of golden foliage of this Rosenkranz Arborvitae (Thuja occidentalis 'Rosenkranz') create some warm color in this season. The green backdrop (a weeping common juniper) helps set the color off. This beautiful dwarf conifer is not readily available in local nurseries.

The blue needles of the St. Mary's Broom Blue Spruce (Picea pungens 'St. Mary's Broom') are so luxurious in winter. This true dwarf conifer is a favorite of Marvin Snyder of Overland Park, past President of the American Conifer Society and inspiration for our dwarf conifer garden at the north end of the Visitor Center. I like its contrast with the orangish Angelina (fore and background) and reddish Wehenstephaner Gold sedums which are neighboring low groundcovers.

Vintage Gold False Cypress (Chamaecyparis pisifera 'Vintage Gold') is a beacon of gold in the Fountain Garden. It is probably our most yellow of winter evergreens and has a very beautiful texture to the needles and sprays of young foliage.

Little Bluestem (Schizachyrium scoparium) though not evergreen is also at its showiest now when the dried, weathered stems and silky seed heads sparkle when back lit on these low sun angle days. This native prairie grass is a tough perennial that requires full sun and average soil. No extra water is ever required once it is established!

Friday, December 12, 2008

Grass Green in Winter?

Few evergreens remain grass-green in winter but one is just that: a grass!

This is a (now) massive stand of Yellow-groove Bamboo (Phyllostachys aureosulcata) growing as a screen behind the Rock & Waterfall Garden. This woody grass can grow up to 25 feet tall (these are a mere 15 feet). It is a running bamboo so be prepared to control it or cut the new culms (sprouts) in spring. We are harvesting canes off this massing for uses in garden staking and trellising.

A closeup of its culm (stem) reveals a flat side that is yellow -- this is how the Yellow-groove Bamboo gets its name. The invasive shoots of this plant in spring are edible but the main species utilized in Asian cooking as bamboo shoots is Sweet Shoot Bamboo Phyllostachys dulcis. Edible shoot bamboos will be on display in the new Heartland Harvest Garden.

The feathery mass of green is the native bamboo Switchcane (Arundinaria gigantea). This grass is native in southern and southeastern Missouri and quite hardy here. This massing is a backdrop in the Rock & Waterfall Garden. Switchcane is the only evergreen shrub of any size (8 feet) native to Missouri. It provides good cover for wildlife and makes a good screen in natural landscapes.

Steeple-shaped evergreens of Green Giant Arborvitae (a hybrid between Giant Arborvitae a.k.a. to lumbermen Western Redcedar Thuja plicata and Japanese Arborvitae Thuja standishii) really put on a show along the trolley drive to the Chapel. This was originally a mass planting of Scotch Pine. Knowing that disease was ravaging that pine, we planted little one gallon trees of Green Giant Arborvitae from the Botany Shop in Joplin, MO, in between the Scotch pines. The Arborvitae are now 18 feet tall while most of the Scotch Pines are dead (except the one on the right). Green Giant Arborvitae also are shunned by deer!

The blue-green needles of Vanderwolf Limber Pine (Pinus flexilis) are quite showy in this season. We actually have had trouble with Limber Pines getting a needle blight but this one has so far been immune. As with most plants from high mountains, they should be planted in full sun with good air circulation in our hot, humid climate zone.

One of our bluest needled evergreens is the 'Hoopsii' Blue Spruce (Picea pungens) the state tree of Utah and Colorado. Its icy blue needles are so beautiful and striking in the winter landscape.

Loblolly Pine (Pinus taeda) has been a good performer for our heavy clay soils but is pushing its northern limits here. I actually like its apple/yellow-green, long needles. Trees at Powell Gardens (along the nature trail and other wild areas) were planted by the Boy Scouts long ago and the tree depicted is actually a self-sown seedling transplanted to this location south of the Rock & Waterfall Trolley Stop.

Evergreen certainly does not mean "green." The evergreen Leatherleaf Viburnum (Viburnum x rhitidophylloides) leaves turn shades of purple in winter -- this year more red than purple!

Here is a closeup of the winter foliage of the Leatherleaf Viburnum this year. It has beautiful texture as well as color for the winter landscape.

Powell Gardens is a perfect place to see a variety of evergreens in the winter landscape; and you will notice many of them certainly are not green in the winter but a wonderful array of green blended colors including reddish, orangish, yellow, bluish and purplish! All photos taken by Alan Branhagen on December 12, 2008.

Thursday, December 11, 2008

Tardily Deciduous

Yes, there is a horticultural term for deciduous plants that hold their leaves into winter: tardily deciduous. As the temperatures get colder these plants will gradually lose more and more leaves until they are nearly bare by mid-winter.

No, these Northern Sweetbay (Magnolia virginiana var. virginiana) magnolias in front of the Visitor Center are not sick! They are just now beginning to lose their leaves as the cold weather has arrived. Sweetbay magnolias are generally not recommended for such a windswept site but because the planting beds are so poorly drained (wet!), this was a good choice here: Sweetbays are hardier if they have constant moisture and are native to wetlands. As these small trees mature (15-20 feet) they will create a more comfortable space to sit in front of the Visitor Center. The sweet scent of their late spring and summer blooms is intensely lemon-like.

Here is an evergreen cultivar of the closely related Southern Sweetbay (Magnolia virginiana var. australis) 'Milton'. You can see its leaves are still dark green above and blue-green below. Severe cold (-10F) can damage the leaves and make them drop. Southern Sweetbays are usually more tree-like (20-30 feet here) and less bushy than their northern cousins.

Can you spot the tardily deciduous plant in this image? It's the front and center ball of olive green: Winter Honeysuckle (Lonicera fragrantissima). As the weather gets colder more of its leaves will discolor and drop. The pinkish brown leaves to the left are the marcescent (dead leaves that don't drop) foliage of the White Oak (Quercus alba) while the dark green plant in the background is the truly evergreen Southern Magnolia (Magnolia grandiflora 'Twenty-four Below').

A close look at a twig of the Winter Honeysuckle shows a swelling bud: it is a flower bud that may open as soon as next month if we have a spell of mild weather. Winter Honeysuckle has very strongly lemon scented flowers that perfume a wide area. The flowers can be damaged by severe cold but the shrub always continues to sprout new flowers until mid-spring. This non-native honeysuckle is not an invasive like many of its cousins. It becomes a huge shrub that can be trimmed up like a little multi-stemmed tree.

Looking out the windows from the Visitor Center the evergreen Southern Magnolias defy the winter season with lustrous green leaves. Few broadleaf plants are evergreen in our climate. These are some of the hardiest selections and we wonder how they will fare if we again have our record low temperatures.

Looking north from the Visitor Center you can see how the landscape around the Visitor Center has many plants with winter interest -- evergreens! The pair of potted plants are Bracken's Brown Beauty Southern Magnolias, the center left plant is an American Holly (Ilex opaca) and the center right plant is a Lacebark Pine (Pinus bungeana). Stay tuned for more on evergreen plants in the next blog...

Friday, December 5, 2008

Whimsical Christmas Trees

Anne Wildeboor (Horticulturist - Seasonal Displays and Events) ties on the final "star" to our trio of whimsical Christmas trees installed in the Visitor Center's Grand Hall. The trees are a trio of living 'Van Den Aker' Alaska-Cedars (Chamaecyparis nootkatensis) and will be planted outside in the gardens next spring. They are a perfect example of whimsy: some think they look like Dr. Seuss while others are reminded of Charlie Brown's tree. We contemplated hanging a Grinch or Cat-in-the-Hat hat but the red ornament balls do the trick!

The trio of trees with Anne from another view.

Jennifer Comer (Senior Gardener - Perennial Garden) places the finishing strings of lights on the trees. Volunteers began the process yesterday and said the trees were more difficult to light than they imagined.

Janet Heter (Senior Gardener - Rock & Waterfall Garden) adds some holiday color (white, frilly flowering cyclamen) to a container of Teddy Bear Magnolia in the Grand Hall. The finishing touches of the Christmas display are being completed today but you will have to come out yourself to see the final product. By tomorrow the final poinsettias and the last train will be installed. I think this Grand Hall display along with the fabulous retro aluminum Christmas trees in the conservatory create a most interesting holiday display. Enjoy!

Old Hickory

Hickory Nuts are one of the tastiest of the season's wild bounty. Native Americans crushed and boiled them to extract their nutritious fat and oils for use as cooking oil or to add to other foods.

Here I placed some Shagbark Hickory (Carya ovata) nuts on the planting plan for the Living off the Land portion of the new Heartland Harvest Garden. Hickories are a prime example of a native edible. Shagbark Hickory nuts are delicious but it's not easy to crack and extract the nutmeat. It is worth the effort as hickory nutmeat is great raw or in hickory nut pie and other baked goods!

Horticulturist Richard Heter stands next to one of Powell Gardens' old Shagbark Hickories. This tree is only 3 feet in diameter but 100 feet tall (see the series of images below looking up to the crown of this tree). It grows in the core of Powell Gardens up the creek bed behind the Marjorie Powell Allen Chapel. Powell Gardens has several presettlement hickories--the easiest one to see is in the road ellipse in front of the Visitor Center. The bark of local trees is not as shaggy as typical; I will have to find out why.

Hickories are also valued for their strong, shock-resistant lumber and of course it is a favorite for smoking food: hickory smoked flavor is legendary. Hickories are never seen in nurseries and rarely planted by gardeners. A seedling tree can grow a 5 foot tap root--with little above ground growth. With proper root pruning they can be grown in special containers or root bags for transplanting. This strong root growth contributes to the drought tolerance and longevity of the tree.

See below for a quote from my favorite tree book: Native Trees for North American Landscapes by Guy Sternberg. (A great gift for anyone with interest in trees and available at Powell Gardens' Gift Shop).

This is the great tree whose name was adopted by Andrew "Old Hickory" Jackson, the hickory-tough, battle hardened, seventh president of the United States. He even planted a few shagbarks at the Hermitage, his home near Nashville, TN (they are still there today!). It is unfortunate that few others have followed his example, as hickories are notoriously slow to mature and challenging to transplant, and modern folks want "easy" trees. Many of our most magnificent specimens in wooded neighborhoods are remnants of presettlement vegetation, and as they begin to die out, no one is replacing them. Please plant a hickory -- any hickory -- for posterity! My sentiments exactly.

Shellbark Hickory (Carya laciniosa) has the largest nuts of any but they are still hard to crack. These are often called Kingnut or Missouri Mammoth Hickories. We have several of these trees in our Heartland Harvest Garden nursery. They will be worth the wait and I know future generations will be glad we planted them. They usually grow wild in deep soils on flood terraces in our region.
These are Mockernut Hickory (Carya tomentosa) nuts. These nuts are so hard to crack that they make a mockery of anyone who tries. The tree is a magnificent and beautiful plant, especially in fall when cloaked in golden foliar attire.
Red Hickory (Carya ovalis) has reddish tinted brown nuts. This tree often grows on very dry ridges in our region. Botanists have trouble differentiating it from the Pignut Hickory (Carya glabra) whose nuts were at least good for pig fodder.

The toughest of our local hickories is the Black Hickory (Carya texana). This tree grows really slowly and often is just a small tree growing on some or our poorest, driest soils. The trunks of larger trees are charcoal black.
I couldn't find any nuts of our most well known hickory: PECAN (Carya illinoinensis)! This image is looking up into trees in our nursery. Pecan nut husks remain up in the tree like black "flowers." The nuts have fallen and are immediately devoured by a whole host of creatures from people to 'possoms, Blue Jays and crows. Pecans are native to floodplains in the immediate area and several selections that will thrive in our area and produce larger-sized, easier-to-crack nuts than the typical wild trees can now be purchased from mailorder nurseries. These "northern" pecans have rich flavor, superior to the paper shell "southern" varieties commercially grown outside the pecan's native range, which is from Illinois and Missouri southward into Texas.
Some of our pecans in our old nursery are getting quite large. We do plan to transplant some of them, hiring Colonial Nurseries' largest tree spade. These were twice transplanted in youth so should make the transfer. Seedling and sapling pecans are true to their hickory relatives and grow a long deep taproot that makes them difficult to transplant -- the earlier transplantings helped us prune their roots for future moving. Look for these trees in the future pecan orchard of the Heartland Harvest Garden. They are already bearing nuts.