Culture Report: Garden Gems Cercis Collection
What’s better than a native tree that offers three seasons of garden interest? A native tree that offers three seasons of garden interest and fits on a patio!
The Garden Gems Cercis Collection is the result of a partnership between Star Roses and Plants and the JC Raulston Arboretum at North Carolina State University. Bare root plants of ‘Garden Gems Amethyst’ and ‘Garden Gems Emerald’ were first received by Star in 2016. After extensive trials by both partners, it was clear that these plants were game changers for the cercis market.
Maturing at about half the size of a typical cercis tree, Garden Gems lend themselves well to smaller containers and smaller garden spaces. This opens the ornamental tree market to growers who traditionally sell shrubs in 3- and 5-gallon programs. It also makes Garden Gems perfect candidates for deco and patio programs. Retailers have already taken notice of this breakthrough, awarding Garden Gems a Retailers Choice Award at the Cultivate tradeshow in 2023.
Think of Garden Gems as an alternative for Japanese Maples; they have the similar foliage colors, the added benefit of spring blooms, they’re North American natives, and they’re faster and cheaper to finish for growers. These compact trees are currently available in two foliage colors — Amethyst and Emerald — with additional colors and habit forms to be released in the coming years.
Growing Garden Gems from bare root is not unlike growing other cercis varieties. We hope the tips outlined here will help you fall in love with these trees as much as we have.
The recommendations that follow are best practices for successfully growing Garden Gems cercis from bare root. Bare root are available for the spring 2025 season.
RECEIVING BARE ROOT TREES
For Star Roses and Plants, the harvest and grading of bare root trees like Garden Gems cercis begins in early December and is usually finished by early January. Growers receive bare root tree shipments starting in January if located in a mild climate or as late as early March if located in regions like the Upper Midwest or Northeast U.S. The extended period of time between first harvest date and last shipping date necessitates a plan for proper storage of dormant plants.
Bare root cercis plants should be stored in a refrigeration unit with good ventilation. Upon receipt of dormant bare root plants, make sure to water the roots and store between 35º F to 40º F. To prevent drying down of roots during storage, keep them consistently moist with additional waterings when needed. Soak roots immediately prior to planting, making sure not to soak for more than four hours.
GROWING MEDIA
Container media should have 50% to 70% total porosity and should average 10% to 20% air-filled porosity. The desired pH for growing media is 5.8-6.8. Prior to planting, prune back any broken branches. It is extremely important to keep bare root plants from drying out through the entire planting operation. During planting and spacing, be sure that the trees do not go an extended period without water and that they are not exposed to temperatures below 22° F. Firming the soil around the roots during potting helps to mitigate air pockets that cause drying.
TRANSPLANTING BARE ROOT TREES
Select a container size appropriate for the size of the bare root plant being received. Garden Gems cercis do best in 3-, 5- and 7-gallon containers. Root pruning is not recommended unless the roots are too big for the container, in which case, trim only the minimum and curl the rest of the roots carefully into the pot. For cercis, it is critical to plant bare root inputs at a depth of 2 inches from the graft point to the top of the soil level. Be sure that the root collar is planted just below the soil level. Planting too deep can result in the tree struggling to break dormancy, stunted looking new growth or death of the plant. If staking, do so at the time of potting.
TOPPING AND TRIMMING BARE ROOT TREES
Make sure to top and trim the trees within two weeks of potting. Cut the leader at a 45-degree angle to a height appropriate for the container. For flowering trees, it’s recommended to top a 3- or 5-gallon at 38-42 inches and a 7-gallon at 45-48 inches. Trim lateral branches back to 3-4 inches. Three-gallon containers planted in March will finish by June. For larger containers, grow on and overwinter. Plants will be saleable the following season.
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