Plants of the Year – 2014

Lots of organizations designate special plants of the year to highlight plants with great features and help gardeners choose plants to add to their landscape.  Here are some of the choices for 2014.

The Delaware Nursery and Landscape Association (DNLA) has been choosing a woody plant (tree or shrub) and a herbaceous plant (one that dies back to the ground each year) yearly to promote to Delaware gardeners.  A selection committee that includes industry members, garden writers, university professors, local landscape designers, and local landscape consultants comes up with a list of plants that meet the criteria each year.  The plants must be available in the nursery trade (nothing is more frustrating than reading about a plant and then not being able to find it to buy and plant in your garden).  They must also grow well in our region, have few pest and disease problems, provide an interesting or showy element to the garden and be somewhat underused in the Delaware landscape.  What is the point in promoting a plant that is already overused!  Then the DNLA board of directors’ votes on the plants they think best meet the criteria from those nominated plants.  Everyone has their favorites and the discussion can get sticky at times, but the process routinely churns out great plants that Delaware gardeners will enjoy in their home landscapers.  The two choices for 2014 are:

 Paperbark Maple (Acer griseum) – This small tree grows in moist, well-drained soil in full sun to partial shade. It has an oval to oval-rounded habit and is known for its peeling, cinnamon to reddish brown bark. Trifoliate leaves are dark green, but turn red in the fall. Its seed is a two winged samara.  It has no serious disease or pest problems. Paperbark maple is a slow grower (6 inches – 12 inches per year) and makes an excellent tree specimen tree for small properties. It is appropriate as an understory tree in a woodland garden or as a specimen in many locations around the home.

Christmas Fern (Polystichum acrostichoides ) – This fern is best grown in organically rich, dry to medium moisture, well-drained soils in part shade to full shade. It will tolerate a dry site better than most ferns. Christmas fern is a local native that can be found on both dry and moist wooded slopes, moist banks and ravines. It typically grows in a fountain-like clump to 2′ tall and features leathery, lance-shaped, evergreen (green at Christmas time as the common name suggests) fronds. While it is considered evergreen and provides winter interest (unless the ground is covered in snow!), the old foliage is pretty beaten down by the end of the winter and gardeners will be looking forward to young fiddleheads emerging in spring. There are no serious insect or disease problems. But, avoid planting in poorly drained soils, where crown rot can be a problem, particularly in winter. Christmas fern looks great in woodland gardens, shade gardens or shady areas of borders, wild or native plant gardens. It can be planted in shady areas along walls or foundations. Christmas fern is a good plant for massing on slopes (including dryish, rocky ones) to help combat soil erosion.  Another big benefit in our area is like all ferns, Christmas fern is deer resistant.

 The Society of Municipal Arborists has named Persian ironwood (Parrotia persica ‘Vanessa’) as their 2014 street tree winner.  Parrotia was chosen for its many merits including resistance to drought and pests, upright habit, hardiness, slow growing smaller size, fabulous fall color and interesting bark.

The Perennial Plant Association also picks a plant of the year and for 2014 that plant is Northwind switchgrass (Panicum virgatum ‘Northwind’). This tall ornamental switchgrass has a distinct vertical habit. It is the sturdiest of the cultivated switchgrasses – guaranteed not to flop. Olive-green to blue-green foliage turns tan in the fall and along with its airy flower panicles provide great winter interest.  By the spring, this still-bold foliage has almost a white color and looks striking when combined with an evergreen, like Eastern red cedar (Juniperus virginiana). It looks so good, it might be hard to cut back the foliage in the spring to make room the new growth.  But, never fear, Northwind switchgrass will grow back quickly and provide a great backdrop for other plants in the garden.

The National Garden Bureau picks a flower, vegetable and perennial each year to showcase and the 2014 choices are petunia, cucumber and Echinacea (coneflower).  There are many great new coneflower cultivars available.  In 2009, Mt. Cuba Center conducted an evaluation of many Echinacea species and cultivars for our region.  A copy of the results can be found at http://www.mtcubacenter.org/images/PDFs-and-SWFs/Mt_Cuba_Report_Coneflowers_for_Mid-Atlantic.pdf.

Not be outdone, the International herb association also picks an Herb of the Year™.  The selected herb must be outstanding in at least two of the major herb categories—medicinal, culinary or decorative.  The 2014 Herb of the Year™ is Artemisia. This diverse herb family contains many strikingly different plants, from the highly decorative Artemisia ludoviciana ‘Silver King’ to the delicious and tender French tarragon (Artemisia dracunculus ‘Sativa’). Artemisia has a long history, prominent in folklore, its virtues used in numerous ways: to protect and heal, create tasty beverages and foods, decorate the home and work its magical properties.

Finally, 2014 in the Chinese Year of the Horse.  What does that mean for plant lovers?  How about planting a horse chestnut in your garden?  Horse chestnut (Aesculus hippocastanum) is a large tree native to the Balkans that has palmately compound leaves and very showy flowers born in upright panicles.  Our native Aesculus is Aesculus parviflora (alright its common name is bottlebrush buckeye-so connecting this plant to the year of the horse is a stretch) and it is a wonderful, summer-flowering shrub that forms a large mounding colony.  It is quite showy in bloom or in fall color.

A recent article in Audubon Magazine written by Susan J. Tweit (January-February 2013) highlights the importance of planting native shrubs with high fat berries to support our overwintering native songbirds.  Consider the black-capped chickadee, one of the most common North American wintering birds.  They lose heat quickly because they have a large surface area for their size.  They have to feed all day on foods rich in antioxidants and fats.  Then they spend the night crammed into tiny cavities shivering and burning the day’s fuel.

You can help chickadees and many other birds by planting native shrubs and trees with high fat berries. Choose native plants because birds recognize them easily and have to spend less energy foraging. Another benefit of choosing native shrubs is they will support native insects and provide food for baby birds in the spring.

A study conducted at the University of Rhode Island looked at the amount of fat stored in different types of berries.  They found the best berry for fat content was our native bayberry, Myrica pensylvanica, with berries that are half fat! Northern bayberry is a large, semi-evergreen shrub that can get rangy with age.  It makes a great plant for the back of the shrub border of in a naturalized setting.  If you want a more refined selection for a small garden, consider planting Bobbee™ bayberry (Myrica pensylanica ‘Bobzam’).  This cultivar will stay compact, but still provide lots of high fat fruit for the birds.

^{Source: Designing Gardens with Flora of the American East, 2010, by Carolyn Summers} 

Some other plants recommended for winter fruit include:

 Wax myrtle (Myrica cerifera) – Smaller bayberry that grows well in the coastal plain, especially at the Delaware beaches.

Southern arrowwood (Viburnum dentatum) – Prefers sun to partial shade, moist, acidic soil; foliage rich burgundy in fall; important for native bees and butterflies as well as birds.

American beautyberry (Callicarpa americana) – Likes light shade and will grow in the hottest areas; moist soils; gorgeous purple berries; deer love to browse

Common hackberry (Celtis occidentalis) – Drought-tolerant, craggy tree with knobby bark; fruits eaten by many bird species; attracts butterflies and moths.

Staghorn sumac (Rhus typhina) –Large rangy shrub for big natural areas, leaves turn brilliant scarlet and orange in the fall and berries are high in vitamin C.

Smooth sumac (Rhus copallina) – A little smaller shrub with great red fall color with berries high in vitamin C.

Aromatic sumac (Rhus aromatica) – This sumac is lower growing and has a cultivar, ‘Gro Low’ that makes a great groundcover.

Winterberry holly (Ilex verticillata) – Many cultivars of this popular deciduous holly have large, red fruit (or orange) that can last well into the winter.

Depending where you live and the bird populations present, you may find these shrubs are stripped of their fruit well before they would help our overwintering birds.  In that case, you are helping the fall migrators.  But, the more people who plant native shrubs, the more food we’ll be providing and that can’t do anything but help those birds we love to watch!

Forcing Bulbs and Branches for Winter Color

If the winter silhouettes of trees, red berries and white snow are not enough horticultural beauty for you over the next several months, try forcing bulbs and branches for early bloom.  These early flowers will easily brighten up any winter day.

To force bulbs, first purchase high quality bulbs.  Tulips, daffodils, hyacinths, crocus, scilla, lily-of-the-valley all work for forcing.  Some bulbs, like paperwhites, do not need a cold treatment, but most fall bulbs (means normally planted in the fall to bloom in spring) require a period of cold before they will bloom.  Don’t mix species of bulbs because they have different forcing times and probably won’t bloom together.

Begin by potting the bulbs in clean, sterile clay or plastic pots. Do not bury the bulbs; leave the “noses” of the bulbs exposed. The soil should be a mixture of good garden loam (three parts), peat moss (two parts), and sand (one part). You can also use a commercial soil-less mix, but be careful the medium doesn’t stay too wet.  Don’t worry about soil fertility or feeding bulbs because they have enough stored food to flower one time.

Plant the bulbs close together in the pot. Usually 6 tulip bulbs, 3 hyacinths, 6 daffodils, or 15 crocus, will fit into a 6-inch pot. Place the flat side of the tulip bulb next to the rim of the pot since the largest leaf will always emerge and grow on that side, producing a more desirable looking pot.  Fill the pot loosely with soil.  Don’t press the bulbs into the soil. Allow 1/4-inch of space at the top of the pot so it can be watered easily. Water immediately upon planting, and never allow the soil to become dry.

Bulbs require a cold temperature treatment of 35– 48 degrees F for a minimum of 12–13 weeks. This cold treatment can be provided by either in a cold frame, an unheated attic or cellar, or even your refrigerator’s vegetable section. In the refrigerator, the pots should be covered with plastic bags that have had a few breathing holes punched in them. With cold frames, cover pots with deep mulch for insulation. The bulbs must not be allowed to freeze.

If you are starting this process in January, you won’t get to bring bulbs indoors until March, but bulbs should bloom quickly once brought indoors.  (Ideally, this process should be started in October or November to get bulbs that will bloom all winter).  A temperature of 50–60 degrees F is preferred for the first week or until the shoots and leaves begin to expand. Then, they can be moved to warmer locations such as the living room. Avoid direct sunlight. Once the bulbs are blooming, move the pots to a cool location each night. The cooler temperatures will prolong the life of the flowers. Small pots of crocus can even be placed in your refrigerator overnight.

Discard tulips, narcissus, crocus, and hyacinths after flowering as they normally are “spent” and are not likely to ever flower satisfactorily again.

Hyacinths, crocus, and narcissus also can be forced in water. Special clear, glass vases are made for hyacinths or crocus. Place the bulb in the upper portion, water in the lower portion. Keep the vase in a cool, dark room (preferably under 50 degrees F) for four to eight weeks until the root system has developed and the top elongates. At this point place it in a bright window, where the plant soon will blossom.

If the whole cold period process sounds intimidating, try using bunch-flowering narcissus, such as Paper White and Soleil d’Or, that don’t require a cold period.  Grow them in shallow pans of water filled with crushed rocks or pebbles. Secure the bulbs in the pebbles deeply enough so that the basal plate is in contact with the water. Keep them in a cool, dark room for several weeks to ensure root growth, and then place in a sunny location. Each bulb will send up several flower stems bearing many tiny blossoms. Discard these plants after flowering.

Another easy option is amaryllis. The amaryllis is a tender bulb that will bloom without special treatment. Pot it in light, rich soil in a pot that is only 1–2 inches larger in diameter than the bulb. Plant so the upper half of the bulb is exposed above the soil. After watering thoroughly, allow the soil to become quite dry. Water more frequently after the flower stalk appears, but never water when the soil is already moist. Put the plant in a warm, sunny spot until the flower buds show color, and then move it out of direct sunlight.

Another easy option for getting spring blooms indoors during the winter is to cut branches of spring flowering plants and place them indoors in water.  Some cherries and witch hazel will start blooming now.  Pussy willows, winter hazel (corylopsis), flowering quince, forsythia, and any other spring blooming shrub can be brought indoors about a month before they normally flowers outdoors.  Place stems in water and change the water every few days to keep it fresh and oxygenated.  Place in a warm, sunny location and watch the wonderful process of opening buds.  You can even force non-flowering stems, like beech.  An unfurling beech leaf bud is subtle but as pretty as most flowers.  Some branches, like red-twig dogwood, will root in water indoors and can be planted outdoors as soon as the ground warms up in the spring.  So not only will you enjoy flowers and leaves during the winter, you’ll become an amateur propagator!

Fall has arrived in Delaware!  Leaves are starting to color and will soon be falling to the ground.  Just as we get a reprieve from grass cutting, it is time to deal with fall leaves.  But, can’t we just let the leaves sit where they fall, that’s what happens in nature, right?  No one rakes up the leaves in a forest.  True, but no one is trying to grow a non-native ground cover in the forest either.  Turfgrass, the primary component of most lawns requires light to grow and in fact to simply survive.  It requires about 4 hours of light per day.  So when leaves fall from trees and sit on the lawn, they exclude light, eventually killing the lawn below.  How do we manage those fallen leaves?  One solution is to have less lawn in your landscape.  Only use lawn where you need a path, gathering space or play area.  The rest of your landscape can become something else, like a meadow, a forest or a landscape bed.  There is no need to rake leaves in a meadow – not too many fall there because a meadow is mostly tall grasses, rather than trees.  Leaves that fall in the woods or in a landscape bed can be allowed to simply stay where they fall and provide mulch for the plants in the bed or woods.  Depending on the ground cover in your landscape bed and the size of the leaves, you may need to rake some of those leaves, chop them up in your mower and spread them back on the bed.  A few more steps, but the result is great natural mulch that sifts down through the ground cover.

So how about the remaining lawn?  You have several choices.  The easiest option is to keep mowing your lawn, even though the grass isn’t growing much.  If you have a mulching mower, you can simply let the chopped up leaves fall right back into the lawn where they will decompose and provide nutrients for your lawn to use as it grows roots in late fall and early winter.  Some of those decomposed leaves will also provide nutrients for spring green up next year.  If you would rather bag your chopped leaves, you can use them as mulch on landscape beds or vegetable gardens that you are putting to rest for the winter.  Leaf blowers can be used to blow leaves off the lawn and into beds but they won’t be chopped up so be careful not to smother ground covers.  Another option, if you like lots of equipment, is to buy a leaf vacuum, which will vacuum the leaves, chop them finely and produce mulch that is excellent for placing around delicate plants and ground covers. Whatever you do, DON’T let the valuable resource of your trees’ leaves exit your property.  Reuse them somewhere in the landscape.  Sustainable landscaping is all about letting biological processes occur naturally in the landscape.  Leaf fall, decomposition and recycling of nutrients back to the soil (and ultimately to the plants growing in that soil) is one of those important natural biological processes.

Leaves raked from the lawn provide mulch for this grove of trees.

After a summer of heat, rain, sun, humidity — yes, we’ve had it all — are you ready to buy and plant some new perennials?  If so, the UDBG Fall Plant Sale is for you!  Fall flowering plants are essential as nectar soruces for migrating monarchs, red admirals and hummingbirds, as pollen and nectar sources for native bees, and as the plants that will set seed for wintering birds.  All of these creatures partially depend on your garden to provide these plants. The Fall Plant Sale is Thursday, September 12, 4-7 PM (UDBG members only), Friday, September 14, 4-7 PM and Saturday, September 14, 9 AM – 1 PM.  Lots of native and non-native perennials are offered for sale.  To learn more about the plants, come to the Guided Plant Walk of Fall Sale Highlights  on Thursday, September 5, 4 – 5:30 PM, led by Dr. John Frett.  Cost is UDBG members $5; nonmembers $10.  Or attend the Fall Plant Sale Highlights Lecture – “Birds, Butterflies and Blossoms:  Perennials that Attract Birds & Butterflies.”  On Tuesday, September 10 at 7 PM join Chanticleer’s Lisa Roper as she discusses the recipe for success – the right plants, and the cultural conditions for them to thrive.  Lisa will also dazzle us with examples of attractive combinations.  Cost is UDBG members $5; nonmembers $10.

Echinacea is just one of the bird and butterfly attracting perennials you’ll find at the Fall Plant Sale.

Do you plant the same annuals in the same locations year after year?  If so, you are like most of us, you find a system or design you like and stick with it.  But, this strategy may cause you problems.  When you plant the same species in the same location year after year, and it is prone to a disease, it may have a little bit of disease present one year, but the inoculum builds up from year to year and eventually you get to the point where you simply can’t grow that plant in that location any more.  This has happened in the Midwest with impatiens downy mildew and it has moved east.  Few plants have the flowering impact in the shade provided by impatiens, but if you have impatiens plants with yellowed leaves, stippling, or white growth on the undersides of leaves, you may have downy mildew.  As the disease progresses, plants appear stunted and foliage drops, resulting in green, leafless stems.

Downy mildew can develop in the home landscape in three ways: it occurred last year and overwintered in plant residue; it was brought in this year on infected plants even though they showed no signs of the disease; or it got blown in by wind and rain from a neighbor’s yard.

Moisture is the key that allows the disease to spread from plant to plant in a landscape bed.  We’ve certainly had plenty of moisture this year and plants that are grouped together in shaded locations where they never dry out are especially susceptible to this type of disease.

The best control is to remove infected plants and prevent inoculum from overwintering.  Then try some new shade loving annuals and expand your horizons.  Alternatives include New Guinea impatiens, begonia, caladium, cyclamen, fuschia, lobelia, perilla, and torenia.

Caladium