Neighborly Garden News
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Are native cultivars as good for pollinators as native species?
There has been a growing demand for native plant material to address pollinator decline in the United States. Creating pollinator friendly landscapes has been promoted as having ecological benefits, and good for our environment. Consequently, this has led to the selection and breeding of native cultivars. A native cultivar or ‘nativar’ is a cultivated variety of a native plant that has been cross-bred and/or hybridized by plant breeders seeking certain desirable traits. The flowers of nativars may vary from native species by the size, shape, color, abundance and bloom time. These attributes are known to affect pollinator behavior; how and when pollinators will visit the flowers. Nativars are also bred and selected for disease resistance and more garden friendly sizes; which could make them more desirable landscape plants.
However, when humans choose traits they find attractive, such as double flowers or unusual colors, these traits may be less alluring to pollinators, and actually decrease the quantity, quality, and accessibility of the plant’s nectar and pollen. Generally, only native species are used in land restoration projects, however nativars are widely used in the landscape industry; it is actually hard to find true native species at local garden centers, it is almost impossible to find a non-cultivated variety of Echinacea purpurea these days.
With agencies like the ‘National Pollinator Garden Network’, and ‘Pollinator Health Task Force’ working to register and improve millions of acres of land and pollinator gardens, it is crucial that we investigate how nativars compare to native species. Do they perform the same ecological functions in pollinator habitats? Annie S. White, doctoral student of Plant and Soil Science at the University of Vermont, has been studying this topic. Under the guidance of Dr. Leonard Perry, she established identical experimental pollinator gardens in northern Vermont locations (zones 4a and 4b). Ms. White has been studying pollinator visitation to 12 native species, and 14 nativars, evaluating garden performance, and nectar production.
One very strong trend was observed across all species evaluated; the more manipulated the cultivars became; the less attractive they were to pollinators. Nativars that were the result of many repeated breeding selections had significantly fewer visits from pollinators. However, some nativars attracted as many or more pollinators than the species. These were typically those varieties that were selected from open pollinated seed nativars such as: Asclepias tuberosa ‘Hello Yellow’.
Asclepias tuberosa ‘Hello Yellow’
The nativar Veronicastrum virginicum ‘Lavendelturm’ (aka ‘Lavender Towers’) unexpectedly attracted many more pollinators than the native species, and actually performed better as well. The results strengthen the idea that there is potential to select and market those varieties that have more appeal to our pollinators.
Veronicastrum virginicum ‘Lavender Towers’
Nectar production was also affected by hybridization of native species. Our native Lobelia cardinalis, which is pollinated by hummingbirds, has been hybridized and also crossed with the native Lobelia siphilitica (which is bumble bee pollinated). The resulting plants have beautiful flowers, but offer decreased volumes of nectar, and nectar sugars than the non-hybridized species. These plants will grow well, and be very showy in the garden, but the pollinators will be rewarded with 20% less of the nectar energy than they would receive from the native species, according to Ms. White. Results may vary regionally, but the research done by Ms. White shows that pollinators, and particularly bees, show strong preferences for native species of flowers. She suggests limiting nativar use in pollinator gardens to those that are open-pollinated and seed grown. Cultivars that differ significantly in color and appearance from the native species should be used only sparingly, and those cultivars derived from crosses of two species should be avoided for use in pollinator habitat restoration.
Lobelia siphilitica-The Great Blue Lobelia
November’s ‘to-do’ list
It would be disingenuous to say this autumn was like no other; as no two years are ever alike. That we are still in the throes of a drought; and many communities continue to clean up after the ‘derecho’ storm from last month, speaks to the extremes of weather we have seen during this past growing season, both here in New England and elsewhere. As I write this, we have finally had a good 24 hours of soaking rain; the first in seemingly months. The rain has helped replenish the deficit, but it is too late for our growing season, as most plants have gone into dormancy already. It is my sincere hope you were able to enjoy your gardens and yards, and it was a place for you to find respite, in this uncertain and frequently sad time.
Keep watering woody plants until the ground freezes. We have had drought conditions summer through fall, and this can have a negative impact on the health of our trees and shrubs. Evergreens, especially, need to go into winter well hydrated to avoid winter injury. Newly planted evergreens may benefit from a timely application of an anti-desiccant type spray, to help minimize winter drying.
There is still time to transplant deciduous trees and shrubs; as long as the ground remains unfrozen, and weather permits. Their roots will continue to grow even though they’ve dropped their leaves. Be sure to water them regularly, and mulch the roots well to retain moisture.
Now that the leaves are down check out your trees for any weakness; broken or split branches that should be removed before storms pull them down. Pay particular attention to any trees adjacent to buildings, driveways or power lines.
Now that roses are dormant, prune them back to 18” tall and use mulch to cover the bud union to 6” deep. Protect the rose canes with a rose cone, or tie the canes together and wrap them with burlap. Prune out any rampant suckers from your lilacs. These take away energy needed to put out flowers. Suckers are the vigorous shoots that emerge from the base of the plant. Leave any major pruning until next year, after the lilacs bloom.
Finish clearing out gutters before it snows. Clogged gutters create ice damns later in the winter; which can lead to leaks and roof damage. Protect your foundation shrubs from snow falling off the roof. Heavy snow and ice can flatten a mature plant in seconds. A simple wooden ‘teepee’ will provide a safe haven, and is re-useable year-to-year. Call our office if you’d like to have us make you a set.
If you’d like to set up a living Christmas tree this year, dig a hole now before the ground freezes, and mulch the hole with straw covered with a tarp to keep the soil workable. It may also be helpful to stockpile some unfrozen soil to backfill the planting hole.
Hang out suet feeders to encourage insectivorous birds to keep scouring your garden for bugs. They will continue to hunt for insects, just beginning to hide for the winter, throughout your beds. Consider adding bird friendly shrubs for food and shelter throughout the seasons to your garden. Even if you feed birds, they still need a place to fly back to quickly, to hide from predators. Hawks in particular love to swoop down on bird feeders and snatch away unsuspecting birds. It is important to thoroughly clean and disinfect feeders before each feeding season. Birds require water throughout the year, adding a heater to your birdbath, can help with their survival through winter.
Need a hand with fall cleanup chores? Give our office a call: (413) 458-5586 or email: firstname.lastname@example.org
Adapting our gardens for happier plants
If we first consider how plants grow in the wild, it can illustrate how truly different our cultivated gardens are. Plants are social creatures; having evolved to be members of diverse social networks. For example, in the wild almost all the soil is covered with groups of interconnected plants. In our garden beds, plants are often arranged as solitary specimens surrounded by seas of bark mulch.
Many plants have adapted to grow amongst other plant communities; for example: Asclepias tuberosa, a great addition to the pollinator garden, will put out flowers at exactly the same height as the grass it grows with. It has developed leaves and roots equipped to grow through the dense foliage and fibrous roots of its companion plants.
According to Thomas Rainer; author with Claudia West of “Planting in a Post-Wild World: Designing Plant Communities for Resilient Landscapes”, the next wave in horticulture will be planting in communities of interrelated species. This concept is a hybrid of ecology, and horticulture; fusing the functionality and biodiversity of ecology, with the beauty, color and order of horticulture.
Research developed by Richard Hansen, & Friedrich Stahl created a scale to rank a plant’s ‘sociability’ and inclination to spread on a scale of 1 to 5. A low sociability plant is almost always found growing by itself in the wild. A high sociability plant will spread to form large colonies. Plants are arranged by the sociability ranking. Plants with low numbers (1,2) will be set individually or in small groups, higher ranking plants (3-5) get planted in swaths of 10-20, arranged loosely around the other types.
This explains why some groupings just never seem to work well; large groups of Echinacea always seem to flop over, and masses of phlox invariably get mildew (both are ranked as level 1 in sociability) in the wild, tall phlox usually grows up through much shorter plants, and because of good air circulation, never gets mildew.
There is a wealth of information on what plants to grow for different conditions, but little written about how to group them so they will co-exist harmoniously. If we study a plant’s shape, this will help you understand its sociability rank. Upright or spiky plants with low or minimal basal foliage have adapted to grow up through other plant groups. Spreading, suckering plants are adapted to grow beneath other taller species.
‘Layering’ your garden in this way, will create a biodiverse ground-cover layer, and a more design-oriented upper layer. So take a second look at your garden; how social are your plants?
Do you feed birds through the winter? Even though birds will take food from bird-feeders, this is only a supplement, and they get most of their food from the plants and insects around them. Try planting trees and shrubs to provide a living winter food source, and offer protection from predators and winter weather for our feathered friends. Plants that will provide autumn and winter fruit and nuts are good choices.
Ilex verticillata-Winter-berry Holly is an outstanding native plant. This deciduous holly bears bright red berries, very attractive to birds, and great for Christmas decorating. There is also an orange fruited Winter-berry Holly variety. Grows 3-8’ tall, depending on the cultivar. Winter-berry Holly is known for its propensity to grow in wet or swampy locations, a plus if you have a wet area to landscape. Ilex verticillata will grow in full sun to full shade exposures, it is very adaptable.
Ilex verticillata ‘Winter Gold’
Ilex verticillata ‘Winter Red’
Rhus typhina-Staghorn Sumac develops dramatic red fall leaf color; the female plants bear red plumes of tiny seeds. I’ve seen flocks of cedar wax-wings passing the fruit to each other, enjoying a sumac smorgasbord. ‘Tiger Eyes’ is a cultivated native variety, with attractive fern-like chartreuse colored leaves. This native tree can grows 6-15’ tall, and will grow into colonies of sumac. Prefers well drained soil, and can tolerate dry soil, grows best in full sun, but will thrive in partial sun as well.
Rhus typhina fruit
‘Tiger Eyes’ Sumac
Picea-The Spruce family are majestic conifers, which offer tasty cones for seed eating birds. There are native as well as non-native species available as nursery trees. Spruce also provides necessary shelter from winter storms and a place to roost. Most Spruce are full sized trees, growing 40-60’ tall. All spruce prefer full sun exposure, and moist, yet well drained soil, but will tolerate clay soils.
White Spruce cones
Picea Glauca- White Spruce
Juniperus virginiana-Eastern Red Cedar and its cultivars bear firm berries that persist throughout the year; ready for hungry birds. A handsome native tree or large shrub; Junipers are excellent for creating a sheltered area for birds. There are many cultivars to choose from, grows from 3-40’ tall. Eastern Red Cedar is not fussy about sun exposure, and is adaptable to many soil types.
Eastern Red Cedar berries
Juniperus virginiana-Eastern Red Cedar
Cornus kousa & Cornus mas, are the Kousa Dogwood and Cornelian-Cherry Dogwood, respectively. Typically grown for their beautiful spring flowers; these two Dogwood species develop outstanding edible red fruit that attract many kinds of birds. Typical trees grow 15-30’ tall, some dwarf varieties will only grow to 8’ tall. The Kousa and Cornelian-Cherry Dogwood trees will grow best with rich and consistently moist soils, but are adaptable, once established, to drier conditions. They will happily grow in full sun, or partial shade.
Cornelian-Cherry Dogwood fruit
Cornus kousa fruit