Use & Care NotesCompanion Plants
How to Use and Care for Jack Frost Brunnera in 20-Cell Plug Trays
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Jack Frost is a classic shade perennial with heart-shaped leaves so heavily frosted in silver that only the green veins show through, giving a crackled look. Here is how to get the most from Jack Frost Brunnera 20-cell plug trays: what to do the day they arrive, how to plant them and how to care for them through the first season and beyond.
What comes in a 20-cell tray
One 20-cell tray holds 20 large, field-ready plugs of Jack Frost Brunnera in cells about 2 3/4 inches wide and 3 1/4 inches deep. Each plug has a bigger root system than a small cell, so it can go straight into the garden or into a 1-gallon pot. Planted about 14 inches apart, one tray fills about 30 square feet.
The first 24 hours
Open the box right away and set the tray in bright shade out of the wind. Lift a few cells: if the tray feels light or the soil looks pale, water from below by setting it in an inch of water for 10 minutes, then let it drain. Give the plugs a day or two to recover before transplanting. Plants that have been in a box need 7 to 10 days of hardening off: set them outside in light shade for a few hours, leave them out a little longer each day, and bring them in if frost is forecast.
How to plant Jack Frost Brunnera 20-cell plug trays
Choose a spot with part sun to full shade and rich soil that stays evenly moist. Water the tray an hour before planting. Push each plug up from the bottom of the cell or squeeze the cell; never pull plugs out by the stems. Plant at the same depth it grew in the cell, firm the soil around it and water in well. Space plants about 14 inches apart, their mature width. These larger plugs can go straight into the garden. If your beds are not ready, pot them into 1-gallon containers and plant them out within the season.
Watering through the first season
Plug cells dry out fast. Check new plantings every day for the first 2 weeks and water whenever the top inch of soil is dry. After that, water deeply once or twice a week through the first summer unless it rains. A thin layer of mulch, kept away from the stems, holds moisture and keeps weeds down.
Season-by-season care
Plant in part to full shade in humus-rich soil that stays evenly moist; protect from hot afternoon sun, which can scorch the leaves. Hardy in USDA zones 3-8. Remove spent flower stems after bloom and trim tattered leaves as needed; it rarely needs dividing. Expect flowers starting in early May with peak bloom in mid May, single flush. First-year blooms from plugs are often lighter; the plants put their energy into roots and fill out by the second season.
Winter care by zone
Jack Frost Brunnera is hardy in USDA zones 3 to 8, which includes West Michigan (zone 6). Fall-planted plugs should go in the ground at least 6 weeks before the ground freezes so roots can anchor before winter. In the first winter, add a few inches of loose mulch after the ground freezes to keep young roots from heaving. Check your zone with the USDA Zone Finder and your last frost date with the Frost Date Estimator.
Where to grow Jack Frost Brunnera
Brunnera needs shade and evenly moist soil, so it belongs in a shade garden with hostas and ferns rather than in a sunny lavender bed.
More help
Read more about this plant in our Jack Frost Brunnera field note, or shop Jack Frost Brunnera 20-cell plug trays. Something looks off? The Plant Health Checker can help, and the Care Calendar sends seasonal reminders.
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