Plant Evaluation Notes Chicago Botanic Garden

Over a 12-year period, the Chicago Botanic Garden evaluated 26 taxa of Eutrochium species and related genera with the goal of identifying outstanding Joe-Pye weeds for Upper Midwestern gardens.

Over our 6-year trial, seven asters received five-star excellent ratings for their overall performance. Top-rated asters displayed consistently strong habits, superior flower production, excellent disease resistance, and full winter hardiness throughout a six-year evaluation term. Additionally, 19 asters received four-star good ratings for their strong performances.

From 2001 through 2009, the Chicago Botanic Garden (USDA Hardiness Zone 5b, AHS Plant Heat Zone 5) evaluated 78 Phlox taxa in full-sun trials. Download the results in this PDF.

Spiderworts may be pegged as common garden plants, but their unique flowers and strong habits mark them as uncommonly good garden plants. A kaleidoscopic palette of colors marks the ephemeral blossoms of Tradescantia cultivars. Just over half of the spiderworts in the study received four-star good ratings for their performance and ornamental qualities. As plants begin to turn shabby from decline or leaf spotting, shearing stems to the base will encourage a flush of new growth later in the season.

Throughout spring and summer the spiky flowers of Veronica rise like sentinels in the
sunny garden. Speedwells can be long-lived provided that garden soils drain freely, which is especially important during winter months. A midsummer shearing after the first bloom encourages late summer flowering. Deadheading throughout the bloom cycle produces many new, spikes later in the season.

Balloonflower is a bushy, clump-forming perennial, up to 3 feet tall, with winsome buds and exuberant blossoms in midsummer. In the border or cottage garden, balloonflowers are good companions to other summer-blooming perennials and are long-lived under normal conditions.