Harbingers of spring

Little did I know when I planned to write this article, we would have a week with temperatures in the sixties and even reach the seventies for a few days in February.  It does feel as though spring is arriving early this year.  However, leaves are not out yet and you can still walk through the woods and find some of the early harbingers of spring.  One of my favorites is the skunk cabbage (Symplocarpus foetidus). Much maligned for its smelly foliage, inconsequential flowers and leaves that start to melt down in late spring; it has wonderful qualities as well.  When the forest floor is still completely brown with old leaf litter, you can find the unusual flower buds peeking up through the leaves.  Look in wet woods where skunk cabbage is plentiful and you will find four-to six-inch high hood-like leaves that enclose the flowers.  Some leaves are deep wine or red and others have mottling with patches or stripes of yellow or yellow green.  The leaves usually twist and eventually open to reveal a round flower head peering out. The flower is a cluster of petal less flowers with stamens that protrude, giving it an interesting texture.  Skunk cabbage is one of the first flowers available for our pollinator insects.  Bees are already out visiting flowers this spring, and they are finding skunk cabbage pollen to bring back to their hives.

The large, wide leaves emerge after the flowers.  Their chartreuse green color is stunning in the otherwise barren woods.  Skunk cabbage grow in moist conditions and only last a few months.  The leaves start to die back at the end of spring/early summer.  However, their early flowers are a fun find and their colorful leaves brighten up the bleak woods at the end of winter.

Another early spring ephemeral (plant that comes up in spring and dies back to the ground before summer) is Virginia bluebells (Mertensia virginica).  Virginia bluebells have bell-shaped (duh!) blue flowers borne on spiral shaped cymes at the end of arched stems.  Some flowers are pink, especially in bud.  This flower is another bee and butterfly favorite.  Its bright green leaves also brighten the forest floor in early spring.

Bloodroot (Sanguinaria canadensis) is another early bloomer with white flowers that come out before the leaves in early March.  Delicate white petals and yellow stamens are quite showy.  Leaves emerge after the flowers, are a fleshy consistency, and spread out to a wide toothed platter shape. Bees and flies pollinate bloodroot, but ants spread their seeds.

If you are tired of looking down at the forest floor for spring interest, look up.  Red maple is blooming now!  The flowers have very small petals, but the bright red stamens are showy enough that trees look red when viewed from a distance.

We will probably still have some cold weather to endure at the end of winter and beginning of spring, but seeking out the early blossoms and bright, cheerful leaves of these native woodland species can provide some diversion before the weather warms up completely.  Enjoy!

Mottled twisted leaves are covering early flowers and a few bright green leaves are starting to open on this skunk cabbage growing at the edge of a stream.

Delaware Plants of 2017

Every year the Delaware Nursery and Landscape Association selects an herbaceous plant (usually a perennial that dies back to the ground each winter) and a woody plant (usually a tree or a shrub) to designate as Plants of the Year.  Plants are selected that will thrive in Delaware’s conditions and that have few disease and insect problems.  If sited properly, these plants are guaranteed to succeed.  These plants are often underused in the Delaware landscape.  So, if you purchase one of these plants, you will be a trendsetter in your neighborhood.  The 2017 selections were just announced at the Delaware Horticulture Industry Expo in Dover.

Schizachyrium scoparium ‘Standing Ovation’

‘Standing Ovation’ little bluestem is a warm season grass with blue-green spikey stems and leaves. Leaves have a purplish caste at the base.   Fluffy, light-catching seed clusters appear in late summer/fall.  In fall, little bluestem turns an apricot color that brightens the winter landscape.  ‘Standing Ovation’ has sturdy blades that are thicker than most bluestems, remaining sturdy even in richer garden soils.  ‘Standing Ovation’ with its sturdy habit and excellent fall color makes a good accent or mass planting in a perennial or shrub border.  Cut back in early spring to make room for new emerging leaves.   Little bluestem is a great addition to a meadow.  If you are managing a meadow and want to add some interest, buy a few ‘Standing Ovation’ little bluestems to spark up your meadow.  They can also be planted in a garden bed, but be careful about rick soil.  While ‘Standing Ovation’ can tolerate garden soils, most little bluestems do best in sterile, non-organic soils (i.e. the kind we have throughout Delaware if we aren’t working hard to improve the soil).

‘Standing Ovation’ little bluestem looks fantastic throughout the year. Photo credit: North Creek Nurseries

Taxodium distichum

Bald cypress is a pyramidal, deciduous conifer that grows 50-70 feet tall.  It thrives in average to wet soils, preferring sandy soils, but tolerating anything from dry conditions to standing water. Trunks are buttressed at the base, often developing knobby root growths, called knees, when grown in water. Soft, yellow-green needles turn an attractive orange/cinnamon-brown in fall. Purplish green cones mature to brown.  Bald cypress is a striking specimen tree for a variety of large areas since it tolerates a wide range of conditions.  You can see lots of bald cypress in Trap Pond State Park in Laurel, Delaware.  You can canoe or take a pontoon boat out into the water to see the most northern natural collection of bald cypress trees.  Remember, these trees are deciduous, meaning they lose their leaves in the fall.  So, don’t get out the chain saw when the needles begin to drop.  They are conifers and most conifers are evergreen so you would not be the first person to think the tree had died.


Bald cypress turning coppery in the fall. Photo credit: Rick Darke

Bald cypress needles and interesting cone. Photo credit: John Frett

Visit a garden center in Delaware this spring and pick up one or more of these great plants for your garden!

Fall Leaves – Asset or Annoyance

Of course they are an asset.  Just consider the rich soil of a forest.  Leaves fall naturally and decompose on the forest floor, where they return nutrients for plant uptake and provide organic matter to improve soil structure.  But, when leaves coat the lawn or, in my case, the patio, they can be an annoyance.  A few weeks ago after I had carefully swept and raked both patios on a Saturday, the weather turned cold and windy.  My husband looked out on the patio on Sunday morning and decried “You didn’t do a very good job raking the patio yesterday!”  There were about 4 inches of leaves covering the entire surface.  Haha – grit teeth.  He was kidding, of course, but the chore still required repeating, so — annoyance!

Leaves can’t be allowed to cover the lawn for too long, because they exclude light and prevent the lawn from thriving.  But they can easily be raked into nearby landscape beds and gardens.  If you don’t have enough garden space to accommodate all your leaves, you have two choices.  Either plant more beds (much more attractive and better for the environment than lawn anyway) or compost your leaves.  If you are lucky enough to live within the city of Newark, the city will compost your leaves for you.  Just rake them out to the road and a truck will come and suck them up!  You can pick up composted leaf mulch from the pile on 896.  For those of us outside city limits, we can chop leaves up with a lawn mower or leaf vacuum. They will shrink dramatically in size, making them easier to store.  When they decompose, they provide rich mulch for next year’s beds and gardens.

Leaves can also be used to protect tender plants.  I have been using a wire cage filled with leaves to protect a fig plant that is marginally hardy here for several years now.

Cutting back perennials is another fall garden task.  The more you cut back in the fall, the less you need to do next spring.  But, be sure to leave some perennials with attractive structure to make the winter landscape interesting.  Echinacea seed heads with caps of snow are beautiful and contain seeds to feed birds.  There are many perennials that get beaten down by the winter weather and won’t require much, if any, clean up next spring.  It is important to remove weeds before they go to seed or seed heads from aggressive plants you want to control in your garden.  I have a nice patch of cup plant (Silphiumn perfoliatum), which I love to see bloom in the back of my perennial border, but if I don’t remove the spent flowers, I will have a border that is nothing but cup plant.  In other areas, I want the aggressive plants to spread.  A patch of sea oats (Chasmanthium latifolium) has been spreading in a section of the garden where I want it to take over, so I don’t cut them back until spring, after they’ve dropped their seeds.

Our warm weather has made fall garden tasks a pleasure.  You still have time to rake those leaves into your beds, prune back aggressive perennials, pull a few weeds, pick up sticks and branches the wind brings down and then enjoy a warm fire with the kindling you gathered.


Fig with wire basket of leaves for winter protection.

Fall in Delaware

Cooler temperatures and lower humidity and (thank goodness) some rain have come along with the start of fall this year.  On a recent trip downstate, I saw sweeps of yellow from sweet goldenrod (Solidago odora)—our state herb.  Goldenrod often gets a bad rap as the cause of fall allergies.  In fact, goldenrod pollen is extremely heavy.  It is pollinated by bees, butterflies, moths etc., but not by wind.  It blooms at the same time as the inconspicuously green-flowered ragweed.  Ragweed has light pollen, is wind-pollinated and is the most likely cause of many fall allergies. Contributing to the roadside yellow were also tickseed sunflower (Polylepis bidens) and swamp sunflower (Helianthus angustifolius).  Warm season grasses, switchgrass (Panicum virgatum), Indiangrass (Sorghastrum nutans) and little bluestem (Schizycharium scoparium) are also blooming in great sweeps along our roadways.  Fall is the season in which Delaware’s native vegetation shines.  Along Route 1, groundsel bush (Baccharis halmifolia) is poised to burst into bloom with white fleecy flowers.  Soon our native sumacs (Rhus typhina, Rhus copallina, Rhus glabra and Rhus aromatica) will turn bright red and make a great combination with groundsel bush.  The first fall color we see in Delaware is the crimson color of black gum (Nyssa sylvatica).  At the northern end of Route 1, the black gums are just starting to show hints of red.

Goldenrod, Delaware’s state herb, blooming in community common land in Northern Delaware.

Goldenrod, Delaware’s state herb, blooming in community common land in Northern Delaware.

If you want to do more than view our beautiful fall landscape, there are plenty gardening activities best accomplished in the fall.  Fall, once we get some consistent rainfall, is a great time to plant most trees and shrubs.  Trees and shrubs put energy into root growth in fall, so plants quickly become established in their new sites.  One exception is with evergreens, which do not grow many roots as the weather gets cooler and the day length shorter, so avoid planting evergreens in the fall.  Perennials can be planted in fall, but if you are planting very small plants or plugs, it is best to wait until spring.  Alternate freezing and thawing during winter, pushes small plants out of the ground.

Fall is the best time to renovate your lawn.  Start by evaluating how you use your lawn.  Where do you need circulation? Play areas? Gathering spaces? Or green carpet to unify the scene?  If lawn is not serving a purpose, get rid of it.  Allow it to become a meadow or forest; or plant landscape beds or vegetable gardens in place of unused lawn.  For those areas you do use, a thick, dense lawn will keep the weeds out and serve the intended purpose fully.  Grass seed requires good contact with the soil to germinate.  If you are over-seeding a relatively weed-free lawn, use a hard rake or core cultivator to expose soil before spreading the new seed.  If you are renovating a poor quality lawn, it is best to kill the existing vegetation before seeding.  You can smother the existing grass and weeds with black plastic, but if the area is large and full of perennial weeds, it will be more effective to use an herbicide, such as glyphosate. Take a soil sample to determine pH and nutrient deficiencies.  Correct pH with lime and add nutrients following the recommendations of the soil test.  Next core aerate or till to expose soil.  Then spread grass seed.  Turf type tall fescue is the preferred grass for all of Delaware.  It is drought tolerant and tough enough to withstand modest play and traffic.  Cover your newly seeded lawn area with a light layer of straw or salt hay to help keep the soil moist.  Water frequently (daily at first) until the grass becomes established.  Cut when the grass reaches 3-4 inches with a sharp mower blade.  Dull mower blades may pull the seedling out of the soil instead of making a clean cut.  Fertilize again once grass is established, usually by mid-fall.

More meadows

The trend is growing.  Longwood Gardens has a meadow.  Mt Cuba Center has a meadow.  Winterthur has several meadows.  Isn’t it time YOU manage a meadow too?  As people become concerned about pollinators and bee decline or just want to see more songbirds in their gardens, they are turning to landscaping with native plants and one of the cheapest and easiest ways to get more native plants in your landscape is to manage a meadow.   Dr. Doug Tallamy, professor of Entomology in the College of Agriculture and Natural Resources at UD and author of bestseller, Bringing Nature Home, was the keynote speaker at the recent American Society of Horticultural Sciences meeting in Atlanta Georgia earlier this month.  He spoke about the role native plants play in supporting native insects and more importantly life as we know it.  His talk was the buzz of the meeting (no pun intended).

I just met with a couple who live in Middletown, DE on about 5 acres.  They are tired of cutting grass and managing a lawn plagued by crabgrass.  Instead, they plan to focus on maintaining a small healthy lawn right around the house where they want to entertain and play sports.  The rest of the property is destined for meadow and maybe ultimately a forest.  They started last week manipulating hoses to get the mow lines for the meadow just right.  Then, they plan to kill the existing turf with glyphosate (sold as Round Up or other generic products).  They will core cultivate to open up holes in the soil and improve seed/soil contact when they seed.  They may use the sawdust method, which involves mixing meadow seed with sawdust and spreading a one-inch layer over the entire site.  The sawdust provides a good germination medium for the seed and prevents light from reaching crabgrass and foxtail seed reducing their germination and encroachment into the new meadow.  The best time to seed a meadow is late spring, but now is a great time to start deciding where your meadow will go.  Just stop mowing the sections of your lawn that you want to turn into meadow and see how it looks.  You will get a sense of the shape and feel of the meadow, before it is time to seed next spring.   The gardens I mentioned earlier do a great job of using cues of care to indicate meadow management.  Mow edges around your meadow and mow curving paths through the meadow.  You can add artwork to the meadow or plant native perennials at key intersections or edges.


Path mowed in a backyard meadow.

Path mowed in a backyard meadow.

I have a bee-keeper friend who is taking the simpler route to meadow establishment.  He simply stopped mowing his lawn.  He is still mowing a circular area off the back patio, but the rest of the backyard is starting to grow tall and will hopefully provide nectar for his bees in a year or so.  He needs to apply those same cues of care, by mowing a path from the end of the driveway to the mowed section.  The clean crisp line between mowed grass and meadow is critical.  It will take a bit longer to establish a native plant meadow with this method, but eventually native warm season grasses and perennials, like common milkweed, will grow.   A middle-of-the-road strategy to jump start the meadow is to open up the soil and plant pockets of native grasses and perennials, either from seed or plugs into the now tall lawn.  These plants will eventually produce seed and spread into the surrounding meadow.  You can’t just throw seeds onto an existing lawn, though and expect them to germinate.  Only seed that stays moist and is in contact with the soil will grow.

To manage a meadow, plan to mow once a year in early spring, and possibly again in late June.  This will keep woody plants from taking over the meadow and still allow the native plants to flower.  Jump on the meadow bandwagon; do your part to encourage wildlife; and help provide the ecosystem services we need right in your own home landscape!

Rose rosette and microscopic mites

A writer from the News Journal heard about invasive microscopic rose bud mites in Delaware that are killing plants.  She became concerned and wanted to learn more about this situation.  These are very small eriophyid mites that spread rose rosette disease, also known as witches’-broom of rose, which is caused by a virus (Emaravirus sp.). The disease is limited to plants in the genus Rosa but some roses are believed to be resistant. Its main host is the multiflora rose, which is considered an invasive plant in Delaware. Multiflora rose has a small white flower in early spring and has taken over many natural areas in Delaware.  It can grow as a shrub or a vine and become intertwined with other shrubs and trees in the woods.  Interest in rose rosette has been generated by the threat to garden roses and also its possible use as a biocontrol for multiflora rose.

Rose rosette disease starts as a red color on the underside of leaf veins and quickly progresses to sharply increased growth at branch tips.  The growth is more succulent than normal and colored in various shades of red. Leaves often become deformed, crinkled, and brittle with yellow mosaics and red pigmentation. As the disease progresses, leaves become very small, petioles are shortened, and most lateral buds grow, producing short, intensely red shoots (witch’s broom). The disease causes the plant to be exceptionally susceptible to freeze damage. Symptoms on cultivated roses are typically less severe than on multiflora rose. Symptoms can be confused with some forms of herbicide damage.

The disease is transmitted by an eriophyid mite, a wingless mite that can travel passively in the wind as well as on contaminated clothing and equipment. The mites feed and reproduce in the tips of rose shoots. Females overwinter under bark or on bud scales of living roses. The females move to newly developing shoots where they lay one egg a day for about 30 days. The young hatch in 3-4 days. They can reach adulthood in about a week depending upon temperatures. Multiple generations occur each year until fall when females seek overwintering sites.  The mites are hampered by low humidity and can only survive about 8 hours without being on a host plant.

The virus is transmitted most readily between May and mid-July when plants are actively growing. Symptoms from new infections usually start appearing in mid-July. In general, smaller plants go through the disease stages more quickly than larger plants. Small plants are usually killed in about 2 years, while a large plant may survive for five years in a deteriorated condition.

To control this disease, you can:

  1. Remove ornamental roses with symptoms. Remove and destroy the entire plant including the roots by burning or placing in a plastic bag. Take care when working with diseased plants as you can spread the mites that spread the disease. Bag the plant before removal, cut it at ground level and then dig out the plant’s roots. Soil need not be removed. Clean tools and put on fresh clothing before moving to a disease-free plant or area.
  2. Plant ornamental roses as far away as possible from known stands of multiflora rose. Maintain at least 300 feet between your roses and any stands of multiflora rose. Even greater distance is preferred especially if they are upwind of your desirable rose plants.
  3. Control the disease by controlling the mite. Start mite control early by pruning your roses hard in late winter (back by 2/3) to remove as many overwintering mites as possible and then spray with horticultural oil to kill any remaining mites. Use horticultural oil or soap, which are less harmful to natural predators that feed on the problem mites. Apply weekly during the months of June and July paying particular attention to the new growing tips where the mites will congregate. Refrain from using leaf blowers around roses as they can spread mites.
  4. Help to isolate your roses. Do not plant roses too close together. With extra space between the plants mite movement can be reduced. Also, consider interplanting roses with other ornamental plants.
  5. Using rose rosette disease as an IPM strategy. The multiflora rose is an exotic invasive species that is responsible for the degradation of millions of acres of farmland and recreational areas. Using the disease to control this invasive weed can cut costs and be considered environmentally friendly for reducing the amount of synthetic chemicals used. However, the disease also affects cultivated roses. One should be extremely cautious and good neighbor-minded when it comes to rose rosette disease.

    Multiflora rose growing at the edge of the woods. It would be great if this virus killed multiflora rose without harming our desirable garden roses, but that does not seem to be the case.

    Multiflora rose growing at the edge of the woods. It would be great if this virus killed multiflora rose without harming our desirable garden roses, but that does not seem to be the case.