Herbs in the Garden Attract Beneficial Insects and Pollinators

small thyme flowers

The herbs in my garden live among the annuals, perennials, vegetables, and shrubs. I have not designed a separate, formal herb garden and now every new herb plant gets tucked in any space I can find. If I remember and have time, I harvest the leaves for teas or for cooking. If I forget or get too busy, the herbs just thrive without me. By summer, they are blooming along with everything else but that’s okay, they still serve a purpose. Even if I didn’t get to harvest them, they are helping the tomatoes, peppers, cucumbers, and beans by attracting beneficial insects.

In addition to attracting pollinators such as bees and butterflies, flowering herbs can attract beneficial insects that will destroy the “bad” bugs. These beneficial insects are either predators, i.e., they eat harmful bugs, or parasites–they lay their eggs in or on the “bad” bug which release larvae that consume the bug.

Many of these beneficial insects are small, thus preferring easily accessible nectar chambers in small herb flowers. In many cases the adult insects need the nectar and pollen of the herb flower while the “babies” or larval stage eat the insects we don’t want in the garden. For example, the larval stage of ladybugs, which look like mini alligators, consume aphids, many beetle larvae, and spider mites, among others. One can attract ladybugs into the garden by planting cilantro, dill, fennel, oregano, thyme, and yarrow so the adult form, the ladybug, can enjoy the pollen.

pollinator on oregano

Lacewings are beautiful slender green insects with translucent wings. Their larvae, known as aphid lions, eat a large number of aphids –thus they have a lion’s appetite — and many beetle larvae to name a few. Lacewings are attracted to angelica, caraway, tansy, yarrow, dill, fennel, and cilantro.

Parasitic wasps are small, non-stinging wasps. There are many types but they all destroy pests by laying eggs inside or on the pest. The eggs hatch to release larvae that consume the prey, eventually killing it. Parasitic wasps will destroy tomato hornworms, bagworms, cabbage worms, Japanese beetles, and squash vine borers. The wasps are attracted to dill, fennel, lemon balm, thyme, yarrow, and cilantro.

Tachinid flies look like houseflies but as parasites, they destroy many kinds of caterpillars, Colorado potato beetles, cucumber beetles, Mexican bean beetles, and Japanese beetles in the same manner as parasitic wasps.  The flies prefer cilantro, dill, fennel, parsley, feverfew, and chamomile.

Hover or syrphid flies look like small wasps because they have yellow bands but they don’t sting. The adults–the flies–will “hover” as they drink nectar from dill, fennel, feverfew, lavender, mint, yarrow, and cilantro flowers. The larvae will consume aphids, cabbage worms, other caterpillars, and mealy bugs.

hover fly in the cilantro

Herbs also help beneficial insects by providing pollen and nectar when other annuals or perennials are not blooming yet.  For example, cool season herbs such as cilantro and chervil bloom in the spring, providing an early source of pollen to beneficial insects.

Many aromatic, perennial herbs, such as oregano, thyme, and lemon balm, are not eaten by deer and small animals so they become permanent fixtures or “houses” for beneficial insects. Plus herbs are usually planted in bunches or become small shrubs, providing a large “neighborhood” for these insects.

a beneficial insect attracted to agastache

However, despite the number of plants in the garden, these insects will only stay if there is a need, i.e., food for them, and if the surroundings are hospitable. Beneficial insects seek large populations of bad bugs in order to feed their own population. Some beneficial insects wait to lay eggs until there is enough “food” so it may be that the appearance of many aphids is the trigger to have ladybugs increase their own population because they now know there is plenty of “food.” In other words, if there a lot of aphids on bearded irises, wait to see if many ladybugs will arrive on the scene to correct the problem before reaching for an insecticide. Spraying chemicals may kill or alter the balance of beneficial insects. It is now known that plants that are under attack by bad bugs release chemicals which are signals to the particular type of beneficial insect that would be needed to correct the problem. There may be a little or minimal plant damage in order for the beneficial insects to receive the signal to come to that plant.

Herbs can be useful for their flowers as well as their foliage. Planting several different types of herbs in the garden helps protect the rest of the plants against pests.

 

Day Trip: Visit a Public Garden This Summer

Summer is the time for traveling, exploring, and spending time with family. Thinking of where to go? Consider public gardens and arboreta. Many of these are historic places as well, great for teaching your kids. On my website, pegplant.com, I list gardening books written specifically for the Washington DC metro area. Several of these books, copied and pasted below, are resources listing botanical, public, or historic gardens in east coast states. Check out these books from your local library and plan a day trip with the family. Enjoy your summer!

  • Maryland’s Public Gardens and Parks by Barbara Glickman, Schiffer Publishers, 2015
  • Capital Splendor: Parks and Gardens of Washington DC by Valerie Brown, Barbara Glickman Countryman Press, 2012
  • A Guide to Smithsonian Gardens by Carole Otteson, Smithsonian Books, 2011
  • Historic Virginia Gardens: Preservation Work of the Garden Club of Virginia by Margaret Page Bemiss, University of Virginia Press, 2009
  • Virginia’s Historic Homes and Gardens by Pat Blackley and Chuck Blackley, Voyageur Press, 2009
  • Garden Walks in the Southeast: Beautiful Gardens from Washington to the Gulf Coast by Marina Harrison, Lucy Rosenfeld, Rowman and Littlefield Publishers, 2006
  • Garden Walks in the Mid-Atlantic States: Beautiful Gardens from New York to Washington DC by Marina Harrison, Lucy Rosenfeld, Rowman and Littlefield Publishers, 2005
  • The American Horticultural Society Guide to American Public Gardens and Arboreta:  Gardens Across America, Volume 1, East of the Mississippi by Thomas S. Spencer and John J. Russell, Taylor Trade Publishing, 2005
  • A City of Gardens: Glorious Public Gardens In and Around the Nation’s Capital by Barbara Seeber, Capital Books, 2004
  • Barnes & Noble Complete Illustrated Guidebook to Washington, D.C.’s Public Parks and Gardens, published by Silver Lining Books, 2003
  • Complete Illustrated Guide to Washington DC’s Public Parks and Gardens by Richard Berenson, Silver Lining, 2003

Relax in DC’s Renovated and Sustainable Bartholdi Park

The U.S. Botanic Garden (USBG) has completed the renovation of Bartholdi Park. The new garden is a showcase of sustainable gardening. Created in 1932, Bartholdi Park has served as a demonstration garden for more than 80 years. In 2016, a complete renovation started that also provided the opportunity to increase accessibility, showcase the Sustainable SITES Initiative principles in action, and demonstrate USBG’s commitment to sustainability.

Some of the changes will be noticeable to visitors. For example, most of the plants are native to the mid-Atlantic region. There is an expanded collection of edible plants in permanent and seasonal plantings in a new kitchen garden. Some of the large trees and shrubs were retained while others were placed in other locations in DC. There is more signage and more places to sit and relax. The tables and chairs were made from white oaks that had fallen naturally during a storm. There is a bike rack, additional lamps/lighting, and a water fountain. There will be outside activities such as yoga and nature-in-motion walks. Not so obvious to visitors are structural changes such as using permeable paving and rain gardens to capture rainfall, diverting runoff from D.C.’s combined sewer system. The original soil was saved and then added back with additional compost. Flagstones from previous pathways were salvaged to create new paths.

Bartholdi Park has achieved the SITES gold certification for its sustainability strategies. It is the first project in Washington, DC, to be certified under SITES Version 2. Sites is a comprehensive system for designing, developing, and maintaining sustainable land. The Park serves as a model for communities interested in sustainable gardening landscapes that are accessible and enjoyable by the public.

The story of the renovated Park is shared through new signage in the Park. A new Field Journal, an interactive booklet for young visitors, can be picked up free at the U.S. Botanic Garden’s information desk. Tours of the Park and other activities can be found at www.usbg.gov/programs.

The U.S. Botanic Garden is open to the public, free of charge, every day of the year from 10:00 am to 5:00 pm. The conservatory is at 100 Maryland Avenue SW on the southwest side of the U.S. Capitol. The Bartholdi Park is across the street. All of these photos are courtesy of USBG.

July Pegplant’s Post Giveaway: Proven Winners Color Choice Tuff Stuff Hydrangea

Thank you Proven Winners Color Choice for sponsoring the July Pegplant’s Post giveaway. The winner will receive a Tuff Stuff hydrangea (Hydrangea serrata), in a 3-gallon container. Tuff Stuff has deep pink lacecap flowers that bloom all summer long. This hydrangea has improved bud and stem hardiness in addition to the ability to flower on new wood. Proven Winners is a well known, reliable name in garden centers, Color Choice is their line of shrubs. Look for their distinctive containers at your local nursery. Pegplant’s Post is a free monthly newsletter for Washington DC metro area gardeners. To view a previous issue, click here, and to subscribe, click on the “subscribe” button on right margin of pegplant.com 

Support National Pollinator Week: Plant Trees for Pollinators

sweet bay magnolia blooms in summer

It is amazing that something as small as a bee is vitally important to our food supply. As pollinators, bees transfer pollen thus ensuring that plants and crops develop fruit and seeds for us to consume. But bees are not the only keystone species that we depend on, we also need other pollinators such as butterflies, moths, beetles, flies, and birds, including hummingbirds. About 80 percent of the world’s flowering plants depend on pollinators (the others are wind pollinated). According to Cornell University, pollinators are responsible for every third bite of food we eat.

Unfortunately, pollinator populations have declined due to pesticides, habitat loss, and disease. Gardeners who are aware of this problem have deliberately planted flowering perennials and annuals to provide pollen (protein) and nectar (carbs). Because of their dramatic 90 percent decline in population over the past 20 years, monarch butterflies have received quite a lot of support. Many gardeners are planting milkweed – the one and only plant for monarchs — or trying to produce more butterflies with home kits. Bees too have received national attention. Nurseries promote bee friendly flowers and gardeners have planted bee magnets such as Joe-pye weed (Eupatorium), goldenrod (Solidago), and gayfeather (Liatris).

persimmon fruit, thanks to pollinators

Plant Trees to Support Pollinators

These efforts have helped the pollinators and certainly gardeners have come to appreciate the importance of pollinators. However, an overlooked source of food and protection for pollinators are trees. Trees provide more flowers, plenty of foliage for larva (caterpillars), and a large infrastructure to hold hives and nests. Because of the number of flowers a canopy provides, trees can provide more pollen and nectar compared to annuals and perennials. Plus, as homeowners move from house to house, the herbaceous landscape may change but usually the trees and all of their tiny inhabitants remain.

Plant Small Native Trees for Homes

“Trees are a permanent fixture,” said Steve Nagy, an International Society of Arboriculture (ISA) Board-Certified Master Arborist and Assistant District Manager of The Care of Trees. The Care of Trees is a division of the Davey Tree Expert Company, founded in 1880. Based in Ohio, the Davey Tree Expert Company has offices across North America–Steve is based in a northern Virginia office.

For attracting pollinators in the Washington DC metro area, Steve recommends native trees that thrive in our particular climate (cold winters and hot, humid summers). “We recommend native trees because the chances of them growing well is higher that non-natives,” he explained. For typical suburban lots where space is a premium, Steve recommends swamp white oak (Quercis bicolor), willow oak (Quercis phellos), post oak (Quercis stellata), cucumber magnolia (Magnolia acuminata), sweet bay magnolia (Magnolia virginiana), black gum (Nyssa sylvatica), little leaf linden (Tilia cordata), persimmon (Diospyros virginiana), and serviceberry (Amelanchier).

“Sourwood (Oxydendrum arboreum) is a great tree, too,” said Steve, “It is a typically overlooked native with good fall color.”

Plant Trees that Flower at Various Times

heavy with summer-blooming flowers, the crape myrtle branches bend down

While a tree can provide many flowers, usually it only flowers for a few weeks. Because different pollinators are active at various times of the year, Steve recommends planting trees with various bloom times. Instead of planting the well-known spring bloomers such as flowering cherry trees, flowering plums, star magnolias, saucer magnolias, and redbuds, homeowners can plant summer blooming trees such as little leaf linden (see video below for bees pollinating a linden tree), persimmon, cucumber magnolia, southern magnolia (Magnolia grandiflora), and crape myrtle (Lagerstroemia).

Plant Trees that Support Specific Pollinators

Another reason to plant trees is that certain pollinators require specific tree species or genera. Similar to the monarch butterfly’s relationship with milkweed, the spicebush swallowtail caterpillar only feeds on spicebush (Lindera benzoin) and sassafras (Sassafras albidum). The zebra swallowtail caterpillar only feeds on young paw paw leaves (Asimina spp.) and the pink-striped oak worm moth gets its name from its preference for oaks (Quercus spp.).

paw paw trees are vital to the zebra swallowtail

Plant Trees in the Fall

This week is National Pollinator Week. Now is the best time to learn more about pollinators and to identify new trees to plant to support them. However, summer is not the best time to actually plant trees. Because trees take longer to become established than perennials and annuals (larger plant hence more root structure and more foliage), Steve said the best time to plant trees is in the fall. “If you can get planting done by Mother’s Day,” said Steve, “the tree has a chance to make it through the hot summer but fall is the best time.” Steve also recommends to plant smaller rather than bigger but one can plant bigger plants in the fall. Fall, as opposed to spring or summer, offers warm soil but cooler temperatures, thus the amount of transpiration or water loss is less. The tree can devote energy into root establishment, not making up for water loss due to heat.

For information on how to plant a tree correctly, the Davey website has an extensive collection of articles and videos on tree planting and maintenance. If you need more personalized assistance, Steve mentioned that homeowners can request a free consultation by calling or completing a form on the website. A certified arborist can come to one’s home to evaluate the trees and landscape and devise a strategy to meet the goals for that specific property.

This week, celebrate National Pollinator Week by learning more about pollinators, identifying the best plants and trees for pollinators in your area, and incorporating best practices to protect, harbor, and feed pollinators.

 

This Week is National Pollinator Week: Learn How to Support Vital Pollinators

This week, June 18 to 24, 2018, is National Pollinator Week. Organizations across the country will host pollinator awareness events.  In Washington DC there are several events this week. Also, you can participate in the Million Pollinator Garden Challenge by making your garden pollinator friendly and registering your garden at the site (free). I just registered my Virginia garden, a typical suburban home, for the Million Pollinator Garden Challenge.

For National Pollinator Week in 2016, I featured an herb a day that attracts pollinators. Marjoram, cilantro, dill, sage, chives, basil and thyme are common culinary herbs that when left to flower will attract bees and butterflies. Day seven, marjoram, provides links to the herbs as well as other pollinator related resources and organizations.

This year I am focusing on a different group of plants that attract pollinators, see my article tomorrow on pegplant.com.

Happy Father’s Day! Enjoy a Bouquet of Summer Blooming Bulbs

Happy Father’s Day! In April I wrote an article about creating a container of summer blooming bulbs. Today, the container is in full glory. Earlier in the spring, most of the oxalis bloomed although you can see one lavender blossom on the left. The remaining burgundy foliage complements the color of the lilies. There is one dahlia on the right, this is actually the second one that has bloomed so far. The lilies are large and fragrant and there are several buds too. Looking forward to enjoying this all summer long.

Register to Learn How to Grow and Use 13 Culinary Herbs

On Saturday, June 23, from 10:00 am to 11:30 am, I will teach a class on culinary herbs at Green Spring Gardens. I will discuss 13 herbs, the cultural requirements, culinary uses, and harvesting and preserving methods. This is not a Powerpoint presentation. I will bring the actual plants so you can touch, taste, and smell!  Everyone will receive a handout with herb information and local resources. And, if you know me, you know there will be a giveaway. Someone will go home with an herb plant. Register online for the “Plants and Design: Herbs–A Baker’s Dozen” class at www.fairfaxcounty.gov/parks/parktakes using code 290-387-4801 or call (703) 642-5173. See you on Saturday, June 23.

Native, Deer-resistant, Summer-flowering: What More Can You Want in a Shrub?

A single blossom on a young Calycanthus ‘Aphrodite” in my Virginia garden

I have been admiring Carolina allspice (Calycanthus floridus) in other people’s gardens for a few years, taking photos whenever I can. This is such a beautiful plant I don’t know why other people don’t grow it more often. A native, deciduous shrub, Carolina allspice grows to 5 to 8 feet tall, is deer resistant, and has no major pests/diseases. The leaves are green and large for a small bush and the brown red flowers bloom all summer long.  Pollinated by beetles, the 2-inch flowers look like a cross between a star magnolia (outer strap-shaped petals) and a lotus (curved inner petals with a central, raised button). In the fall, the leaves turn golden yellow.

Calycanthus ‘Aphrodite’ at High Glen Gardens looks like a cross between a star magnolia and a lotus blossom

Fortunately Spring Meadow Nursery read my mind and sent me the cultivar Aphrodite two years ago as part of their Proven Winners ColorChoice collection. Aphrodite’s flowers are redder than the species and are supposed to smell like apples. In my Virginia garden, my 3-foot tall youngster is thriving under the edge of a red maple’s canopy, so it receives partial sun. This past week, Aphrodite bloomed for the first time.

I cut the flower and put it in a vase. There was no scent but I have read that young plants do not always have a fragrance. Apparently this attribute comes with maturity. I did crush a leaf though and the camphor scent was nice, almost lemony. It reminded me of a friend who would put eucalyptus branches in her car so the heat would release a pleasant scent. The bark too was aromatic when I scratched it.  Mark Catesby said the bark was as “odoriferous as cinnamon” although I think the scent is more like a cross between lemon and camphor. When my plant matures and I get more flowers I will use them for flower arrangements. In addition to the flowers, I could use the leaves and branches for potpourris. But I think I will pass on the car trick, it may create a strong odor, more like a disinfectant.

Regardless of its scent, Carolina allspice is a great shrub for the Washington DC metro area. Aphrodite certainly holds great promise in my garden.

Mature shrubs of Calycanthus ‘Aphrodite” at High Glen Gardens, Frederick, MD

Public Gardens and Demonstration Gardens in the Washington DC Metro Area

I have updated my list of public gardens and demonstration gardens in the Washington DC metro area, see tab with same name on my website, pegplant.com. Many of these places are perfect to take the kids and visiting friends and family to this summer.

Public gardens are living examples of which plant performs well in the area. Many public gardens have a reference library, gift shop, web site, and gardening hotline. Usually, public gardens host seminars, workshops, classes, events, and plant sales. They may publish their own books on plants for the area or distribute free handouts. Some have staff horticulturists who can identify plants or answer questions.

Demonstration gardens are a great way to learn what works in our area and how to manage our local issues, such as deer. The gardens are open to the public, every day, from dawn to dusk, free. Each county that has a Master Gardener program usually has at least one demonstration garden, managed by the volunteer Master Gardeners.

If you have suggestions for additions, feel free to send them to me by commenting on this post.