Eva Monheim on Hedgerows

Heartland Gardening recently talked with Eva Monheim, author of “Shrubs and Hedges” (Cool Springs Press, March 2020) about the under-appreciated hedgerow – its rich history, diversity and ecological value. Eva teaches at world renown Longwood Gardens as well as the Barnes Arboretum at St. Joseph’s University. She is co-founder of Verdant Earth Educators, a horticulture education and consulting firm, and was assistant professor at Temple University’s Department of Landscape Architecture and Horticulture for over 12 years.

The valuable large trees in the ancient hedgerow provided valuable shade for early farmers as a place for rest out of the hot summer sun.

What is a hedgerow?

If we look back into history, hedgerows were first developed after humankind transitioned from hunter gathers to the agrarian lifestyle. Woodlands were cut down to create fields to grow crops and strips of the ancient forest were left to protect the crops from wind and other elements. Small narrow lanes were created between the hedgerows, so wagons could pull crops to local villages to store. So, when we think of hedgerows, they were first used for farming. They were also used to protect the crops from animals. As man began herding animals, they also used hedgerows for keeping animals in a field, while trying to keep other undomesticated animals out. More complex hedgerows developed – especially in England where pleaching was developed. Trees were cut halfway through and snapped. These half-felled trees began sprouting and then the sprouts were braided into an intricate lattice structure. This design further curtailed unwanted animals from moving in or farm animals from wandering out.

A farmer maintains a hedgerow in England.

What was their initial ecological appeal?

Early farmers knew hedgerow’s diversity provided pollinators for crops and habitat for birds. Hedgerows here in the U.S. are one of the most threatened habitats, especially by new constructions projects. The first thing to go is usually the hedgerow. Most people think they are junky, but they are anything but junky. They also are critical to prevent flooding downstream, protecting farmers from the elements, and providing additional food sources, like berries and other small fruits. Their structure contains large trees, layers of shrubs and ground covers, perennials, annual plants, and seed store.

Mixed hedgerows develop over time. They don’t have to be perfectly clipped in order to provide valuable services for wildlife. 

How is it different from a hedge?

Hedges came about to define boundary lines other than fields. Hedgerows were a form of protection from the elements, keeping snow on the fields for deep watering before the crops were planted. Hedges came about as gentry began pushing farmers off the land and securing land for themselves. Usually one or two species were used to make a hedge of thick green walls impenetrable to passersby. Hedges are still used like this today as a delineation between me and you – owner and non-owner. In Europe, there is a crossover between hedges and hedgerows. Here, 600- and 700-year-old hedges are called “hedgerows” as they gain a mix of species over time.

What is the value of hedgerows today?

With the few hedgerow remnants remaining in the U.S., they are even more important today. If you are concerned about pollinators – hedgerows are critical for their preservation. Swarms of bees can live in hollowed out trees and old tree stumps. If there are no large woodlands around, these areas are even more valuable. The exposed sides of the hedgerow have valuable habitat for in-ground native bees and other pollinators like bats that roost in the trees. Old snags and logs become a haven for beetles that provide invaluable services for our gardens and crops. Birds also use these habitats for nesting and some birds can live their entire lives in the hedgerow which provides food and protection from the elements. I can go on and on about the value hedgerows – it’s the unseen that is the most valuable – the enormous opportunity for seed store that contributes to diversity. They should not look clean and tidy. They should be strips of diversity.

Where is a good place to add a hedgerow?

While a typical hedgerow can’t be built (it’s an evolutionary process), you can make a pseudo-hedgerow along a property line by creating a layered plant community or buffer. Start with trees. You can start all your plants out small and let them grow into place then slowly fill in with varied understory small trees and shrubs. It would be like building a woodland – but in a narrow strip 10’-25’ wide.

What shrubs do you recommend for a pseudo-hedgerow?

Depending on where you are building your buffer – along a stream or along a boundary, the species will vary depending on the site:

  • Viburnum acerifolium – maple leaf viburnum
  • Viburnum prunifolium – blackhaw viburnum
  • Viburnum dentatum – arrowwood viburnum
  • Viburnum nudum – possumhaw viburnum
  • Prunus virginiana – chokecherry
  • Ilex verticillata – winterberry holly
  • Ilex glabra – inkberry holly
  • Ilex opaca – American holly
  • Lindera benzoin – spicebush
  • Taxus canadensis – American yew
  • Amelanchier sp. – serviceberry
  • Chionanthus virginicus – fringe tree
  • Vaccinium corymbosum – highbush blueberries (needs low pH)
  • Vaccinium angustifolium – lowbush blueberries
  • Hydrangea arborescens – smooth leafhydrangea and there are lots of cultivars too! (you can also use other hydrangea like Hydrangea macrophylla – bigleaf hydrangea and Hydrangea serrata – mountain hydrangea)
  • Sambucus nigra subsp. canadensis or (syn. Sambucus canadensis) – American black elderberry
  • Aesculus parviflora – bottlebrush buckeye
  • Aesculus pavia – red buckeye
  • Rhus aromatica – Fragrant sumac
  • Rhus typhina – staghorn sumac

Some Trees  

  • Maclura pomifera – Osage orange
  • Quercus imbricaria – shingle oak
  • Quercus stellata – post oak
  • Quercus phellos – willow oak
  • Quercus macrocarpa – burr oak 
  • Sassafras albidum – sassafras

How do you go about installing a hedgerow?

I would typically start by planting trees — both deciduous trees and conifers. Remember you are building a remnant of a woodland. There is no need to move or remove any soil or remove any lawn. Plant your trees as if you were planting them in your lawn and plant your shrubs in between. (Make sure to plant long-lived species such as oaks as well as short-lived species such as cherries.) When you have planted all that you can, use newspaper and cardboard over the entire area making sure all the paper products overlap. (There is an art form in doing this. Start at one end and work to the other. Mulch the entire area with triple ground hardwood or woodchips or combinations of mulch. Pine straw is great, too!) Allow the area to settle in for a year to kill weeds and invasive plants and then you can go in and plant additional shrubs and trees and plant bulbs, native woodland flowers and ground covers. Lay a few logs in the mix too for beetle habitat.

How do you expand the hedgerow?

When planting a hedge make sure to leave a well cultivated area around the hedge. They can be planted like the hedgerow (described above) leaving the lawn intact. Make sure to be generous and methodical about using newspaper and cardboard in between, in front and behind the hedge, and cover with triple-ground hardwood (no dyed mulch – too many chemicals in them). A more refined mulch will create a good sound cover. The following year, you can plant perennials, bulbs, or annuals or a combination along the edge to provide a more diverse habitat.You can also use several different types of plants to make your hedge and instead of creating a straight line of plants stagger them – in and out. Plant them the same way as you did the above. The following year, you can plant bulbs, perennials and annuals in the alcoves that were created, maybe even some shorter shrubs that will add different seasonal interest to the hedge.

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