July 2019       Volume 9, No. 6
Dear Friends,

I hope you have been able to stay cool in the hot weather this month!  Remember that anything planted in May and June will need supplemental watering during this time. Please see our summer watering instructions for guidance, and let us know if we can help you keep up with watering or other garden tasks.

Bearded Iris Care and Pest Info

Tall bearded iris
T all bearded iris are the one plant that can be divided and transplanted at this warm time of the year! Blooming from late May into June, these plants enter dormancy in the hot summer. The spreading rhizomes are easily dug up with a spading fork, separated, roots trimmed, and replanted in a gritty soil mixture in full sun. We often bring a bag of builder's sand along for the purpose of "unimproving" rich garden soil. 

Keep iris away from your irrigation system, as they are quite drought tolerant and don't like to be overwatered. You can easily hand water any newly set divisions with a watering can until they "take." That moment comes when you can't pull them up by lightly tugging on their tops. If you're about to be vacationing now, don't despair - this work can be undertaken through the end of September. Iris need a period of time to root and settle before winter.

Iris borer larvae tunneling in rhizome

There is one pest of bearded iris that can be very destructive: the iris borer. You'll be able to quickly identify trouble if you smell something nasty as you handle the rhizomes. Then you'll notice a pinkish worm (the iris borer larvae) moving in and out of tunnels in the rhizome. Immediately bag and discard these plants, as this is the easiest way to contain the problem. Leave the area empty during the hot summer, and don't replant with new iris until next spring, becauase any larvae left in the soil will only invade the new rhizomes!  A better idea would be to rotate the position of your bearded iris to a new full sun spot and try a new perennial in the old location.

We also trim the fronds of tall bearded iris into low fans during the summer and fall to discourage adult iris borers from recognizing the plant and laying their eggs.  In addition, we clean up browned out foliage that is a result of the hot weather.

If you've had a problem in the past with iris borer, it can be effectively controlled in the spring by spraying insecticidal soap on the plants after the first two days of 70 degree weather.  This is a good preventative that is timed when the larvae begin to emerge.

Please let Kim know <> if you'd like our help with maintaining your patch of bearded iris.

And if you want to acquire some new varieties of Bearded Iris for your garden, show up at Verrill Farm in Concord on Saturday, July 27 for the annual sale organized by the Iris Society of Massachusetts. 
Hours are 11 am - 3 pm.

Plant Pick: Rhododendron maximum A1

This beautiful native plant is blooming now!  You may wonder why a rhododendron is blooming so late, and this is a positive ID for
Rhododendron maximum, or the Rosebay rhododendron.  Living up to its name, it is our tallest rhododendron growing 10'-25' tall and wide.  We often use it in designs where year-round screening is called for and place it in a semi-shaded or completely shaded position where it can reach its full potential.  This plant is scrawny when young and takes a few years to fill out, so be patient with it!  As with other rhododendron species, protect from harsh winter sun and wind.

Native from the Appalachians of northern Alabama to coastal Nova Scotia, you can visit both a native stand and a planted drift of mature Rhododendron maximum if you will be in New Hampshire this month.  Rhododendron State Park in Fitzwilliam, NH is located on Rhododendron Road, just off Rt. 119 heading to Brattleboro, Vermont. You can wander through towering plants in full bloom and imagine yourself in the cool mountains of North Carolina.
The Fells, an estate open to the public on Lake Sunapee in Newbury, NH, has mature stands blooming pink, lavender and white in their restored and renovated woodland garden. These plants are very striking from a distance or close up.  More information at <>

Are you Having Deer Troubles? A2

You're not alone.   Munching on daylily flowers, hosta leaves, phlox, sedum, new growth on hydrangea, weigela, viburnum, witch hazel and more has been reported as we make our rounds. The deer seem to seek moisture and tender new tips of plants at this hot time of year.

Deer browse on hosta
Cut back damaged stems and leaves on perennials immediately so that new growth can emerge.  Be more careful with woody plants - let us deal with deer damage on a case-by-case basis.  Radical steps may not be needed.

Damaged hosta

We're helping to keep one step ahead of the deer by placing garlic clips on woody branches or bamboo stakes near vulnerable perennials. These handy items release a strong odor of garlic that the deer don't like. We can also spray your plants with deer and rabbit repellent that is organically approved. This may need to be repeated after heavy rains.

Please let us know if we can help with critter control in your garden by contacting Kim <>

Summer Foods: What and Why

Our compost tea program is now segueing into the summer season with applications of Summer Foods.  This means we are quite literally providing food for the large colonies of microscopic life in your soil through the hot weather.  These "good guys" are actively seeking sustenance so that they can fulfill their role as predators of "bad guys" that may be lurking.  

Summer foods are not actively aerated like the compost tea we supply in spring and fall, but are mixed on site by Plant Health Care Manager Reese or Plant Health Care Technician Roy, then immediately applied to your landscape if you are part of our Plant Health Care Program.

Our soil amending program in the fall provides further slow release food through materials such as lime and greensand that are prescribed by your soil test. We will also pull soil biology tests at leaf drop this fall to see how the levels of microbial life have changed since last year.

Farewell and Thanks to Russell Stafford

Russell Stafford, part-time Crew Supervisor, left us in early July after working with PBOG since 2007.  This spring he relocated to Providence, Rhode Island and found the commute not workable.  We relied on Russell on Tuesdays (and Thursdays some years) to oversee work at many of our largest properties.  He instilled in all of us the importance of timely garden care and a broad knowledge of Latin plant names.  

Good luck, Russell, in your new garden territory!

Priscilla's Garden To Do List for Late July/Early August
  • Lift and divide tall bearded iris now through the end of September ( see article)
  • Keep up with weeding and deadheading
  • Top off mulch if bare soil emerges after weeding or heavy downpours
  • Stake any plant preventatively that threatens to flop
  • Prune spring blooming trees and shrubs
  • Remove spent vegetables from the garden and replant open areas with carrots, beets, summer squash, string beans or radishes
  • Keep up with watering containers and anything newly planted
  • Hold off on transplanting and dividing until cooler weather
  • Visit an open garden in your travels for fresh inspiration
  • Hardscape projects of any type can be undertaken now
  • Keep an eye out for deer and rabbit damage to gardens and take preventative measures (see article)
  • Follow the shade around your property as you work in the garden on hot days
  • Wear sunscreen and tick repellent when you are outdoors, avoiding edge areas where ticks tend to congregate
  • Prune long vegetative canes of roses to force energy into bud making on shorter, productive canes
  • Prune vegetative runners of wisteria
  • Dig and reset strawberry runners to create new plants (if desired) or else clip off this excess and discard, forcing energy into the mother plant roots

Enjoy all the color in the landscape this month!  If you find you're lacking this kind of show, now is the time to work with us on improving the view.   Fall planting season will begin in late August and run through October, so we're happy to meet with you now to design and plan a new planting, large or small.

We look forward to seeing you soon in the garden,

Priscilla and the PBOG Crew

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