Horticultural Garden Notes: 2017 Growing Season

Longenecker Horticultural Gardens, view from the pinetum

Longenecker Horticultural Gardens, view from the pinetum

Weather and Maintenance

Weather extremes posed challenges for the Longenecker Horticultural Gardens collection this year. The growing season started out wet, cool, and cloudy and ended dry and warm. The period from January to July was the second wettest in Madison’s recorded history. That was followed by two months of drought-like conditions, with the warmest temperatures of the growing season occurring in September. These conditions contributed to fungal growth in the first half of the season and drought-stressed plants in the second half.

Garden maintenance continued thanks to many helping hands. We were fortunate to have 173 individual volunteers who logged more than 1,325 hours. Two UW–Madison students also worked with us through the season: Mark Herbeck, a senior in forest science, and Leah Stoltz, a junior in landscape architecture. We also had the help of a hard-working team of nine AmeriCorps members during May and June.

New Plantings

Emerald ash borer feeding galleries

The Longenecker collection is an ever-evolving garden, with changes every year to incorporate new unique plant acquisitions along with the latest woody plant industry introductions appropriate for our area. In 2017, 47 plants from 43 taxa (distinct kinds of plants) were added to the collection. Selections ranged from the pawpaw (Asimina triloba), North America’s largest native fruit, to the chastetree (Vitex agnus-castus), which attracts butterflies in late summer with its spikes of blossoms, similar  in form to lavender, before it dies back to the ground in the winter.

Some specimens are also removed each year, generally due to declining heath or death. During 2017, 39 plants were removed—including a cultivar of black ash (Fraxinus nigra), our first confirmed emerald ash borer casualty.

Deer Fencing

Paper birch damaged by buck rub

A robust white-tailed deer population means that damage to garden plantings continues to be a management issue. Buck rubs were especially prevalent this fall. Male deer generally begin rubbing their antlers and forehead on trees and shrubs in September and continue through December. The rubbing removes the bark and underlying cambial tissue on stems and can lead to deformation, internal rot, and even death of affected plants. While not completely understood, this activity appears to be a way for adult males to signal their presence to each other by leaving both visual (rub damage) and olfactory (scent from glands located between the antlers) markers. Researchers at the University of Georgia identified 57 different volatile compounds produced in the forehead region of male deer. To help mitigate this damage in the Longenecker collection, wire cages are placed around the most susceptible plants to keep deer from the trunks.

Deer fencing is also erected each fall around specimens prone to winter deer browse. When food options are limited, deer are drawn to certain trees and shrubs to supplement their diet, often destroying their ornamental value. In the Longenecker collection, the evergreen foliage of yews and eastern arborvitae are prone to being eaten. Azaleas are also favored for their nutritious overwintering flower buds.

Arboretum Drive Fence

The new Pinetum entrance and split-rail fence in Longenecker Horticultural Gardens

The growing season also brought the beginning of a very special project: the makeover of the fencing along Arboretum Drive near the Pinetum area. Thanks to a generous gift from Arboretum neighbors Leslie Ladd and Bill Hantke, the decades-old woven-wire fence was replaced with a new section of split-rail cedar fence. A stone column entrance across from the Wingra Woods parking lot was also built to welcome visitors to the collection. These new structures enhance the landscape and complement the plant collection. Financial donations are needed toward an additional 2,200 feet of fencing to complete the project bordering Longenecker Horticultural Gardens. If you’re interested in making a donation to the fence campaign, please call Mark Wegener at (608) 265-2450.

—David Stevens, Longenecker Horticultural Gardens curator