June 2019       Volume 9, No. 4 (?)
Hello Fellow Gardeners, and Welcome to Summer!  

On June 21st, the Summer Solstice or the longest day of the year will be here. This milestone usually brings warm temperatures and hopefully a lessening of the frequent rains of spring. Our gardens and landscapes are lush and full of bounty and bloom this month. I hope you can get out and enjoy!

Pruning Season is Here: How and Why We Prune

One cardinal rule is this: after it's done blooming, pruning can happen. So we start in late June by pruning the early spring flowering plants such as quince, fothergilla, lilac and forsythia. Later we'll turn to rhododendrons, azaleas, weigelas, and the like. Evergreens such as yew, holly and boxwood are pruned in the summer once their bright green new growth hardens off. And we will also prune vegetative growth (meaning just leaves on a tall shooting sucker, no flower buds) from wisteria, rose and honeysuckle. Small flowering trees such as crabapple, dogwood and styrax can also be pruned in summer. We wait until August to prune birch and Japanese maple trees so that they do not bleed sap as they do in the spring.

Here at PBOG, we prefer a naturalistic style of pruning rather than shearing plants into balls. So you'll see us out with our hand pruners, saws of all sizes, and loppers. This technique promotes openness so that air can circulate among the branches and leaves, leading to better overall plant health. There will be fewer hiding places for pests and diseases to gather.  

If height needs to be reduced below a window, for example, we will work carefully to remove the tallest branches in a manner that will still promote natural form and bloom. Or we may recommend moving that particular shrub so that it can reach its full potential and suggest a more compact plant for the spot beneath the window.

Priscilla is also available for one-on-one garden coaching sessions where she'll teach you how to prune! Please schedule your appointment here (

June is a month of Pests and Preventative Care

Near complete defoliation of Exbury azalea by azalea sawfly (
Our Plant Health Care Department team, Reese and Roy, are busy this month with spot spraying. Using only organic products, we aim to catch the pest at the propert time for best control.  We often use a Neem oil product for this purpose.

It's time for various sawflies to emerge. Larvae feed voraciously on leaves. The azalea sawfly skeletonizes as it feeds, leaving only a leaf midrib. We'll be watching for the hibiscus sawfly and dogwood sawfly later this summer. Both make holes in the leaves of their specific host plants. Boxwood pysllid is also active and will be monitored.

Of course, our Tick and Mosquito spray program continues this summer.   We are able to spray only on dry days with our natural essential oil product.   The compost tea program provides Summer Foods to microbial populations in the soil as they rapidly reproduce and expand with
warmer soil temperatures.

We've noticed that soils with lower Phosphorus have many fewer pests, as insects find plant parts high in Phosphorus easier to digest.   Make a note to start our soil testing and amending program this season!
Meet Some of our New Staff 

We're proud to introduce a few of our new 2019 staff:

Holly Ben Joseph is a landscape architect from Acton who has a specialty in designing school grounds.  She came to us part-time to learn some new techniques and plants and is especially enjoying pruning and fine garden maintenance work.

Lisa Murray has been active in the Groton community as a volunteer gardener and leader. She continues to be amazed at how much work gets done by our teams on a daily basis, thanks in no small part to her helping hands.

Erica Willis ran her own small design and maintenance business in Groton for several years, then switched to real estate staging. She's now back in the garden, and we're so happy to have her expertise and quick study on the job daily.

Mike Woods has arborist experience, and we're going to be counting on his expertise during the upcoming summer pruning season. He's also an expert edger and is learning more about perennial and annual flowering plants as we make our rounds.

Plant Pick -  Cornus kousa

Cornus kousa
What is the starry white tree that you see blooming everywhere these days? Most likely it's the Kousa dogwood, native to Japan, China and Korea. This is the analog to our native dogwood, the Cornus florida. However, as dogwood anthractnose began to infect native stands, many people decided to plant the resistant Kousa dogwood instead. This tree is 20'-30' tall and wide, has glossy green leaves and four-part ivory or pink flowers. It has a long season of bloom in June and July.  Beginning life as an upright specimen, it gradually becomes more rounded and horizontal as it matures.

Recently, I visited the Wakefield Estate in Milton during a garden party to herald Dogwood Days, the week in early June when about 300 Kousa dogwood trees came into bloom. Polly Wakefield, the late owner of the estate, was a plant enthusiast who took propagation classes at the Arnold Arboretum in Boston. She went on to grow Kousa dogwoods from seed and patented seven cultivars including 'Greensleeves.' All the Kousa dogwoods on the estate were grown by Polly, as well as many other interesting woody plants.  I enjoyed a long stroll through various garden rooms, connected by pathways lined with Kousas. When lantern-style lights came on at dusk, I had an entirely new experience of this tree in bloom!

I have a special interest in Polly Wakefield, as she was a graduate of the Lowthorpe School of Landscape Architecture for Women, which once operated on Main Street in Groton (1901-1945). Ten years ago I was invited to research and lecture on the history of the school and its graduates for the Groton Historical Society. That project sparked my interest in the fascinating early days of the field and fueled my intention to write a book on the school's history in my retirement. There is much primary source information on the school in local repositories that has not been published.

You, too, can visit the Wakefield Estate. Plan your visit at

Priscilla's To-Do List for June:
  • Deadhead iris, peony and rose promptly after bloom and in dry weather only
  • Stake tall plants such as delphinium BEFORE they begin to flop
  • Finish planting by the end of the month so that plants can begin to establish before the hottest weather of the year arrives
  • Fertilize annuals weekly with dilute fish fertilizer or liquid organic fertilizer and deadhead promptly to promote more bloom
  • Clean up bulb foliage as it yellows and fertilize bulbs at this time with an organic bulb fertilizer
  • Wait for bright green new growth to harden off before pruning evergreens and broadleaf evergreens in July and August
  • Prune quince, fothergilla, lilac, forsythia, deciduous azaleas
  • Prune vegetative growth of wisteria, rose and honeysuckle
  • Keep up with weeding and cover disturbed bare soil with a plant or mulch as a preventative against rampant weeds
  • Pinch back tall asters, perennial chrysanthemums, helenium, boltonia, obedient plant, Joe Pye weed twice before July 4th to control sprawl later
  • Refresh spring containers with summer flowering annuals or perennials
  • Keep up with harvesting in your vegetable garden, pulling spent plants and replanting immediately
  • Sow a second crop of beans, summer squash, radishes, lettuce or kale
We hope to see you soon in your garden for some late June planting, a small hardscape project, or early summer pruning!

Priscilla and the PBOG Crew

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