How to Build Winter Potting Containers
Assembling winter potting containers has been a festive way to end our gardening season. One of our head gardeners, Calla Butler, remarked, "they're a reminder that the gardening season never ends." Customers who want a cherry on top to their growing season ask for winter potting containers.
Atzinger Gardens started offering winter potting containers in 2019. They are installed weeks before Christmas, but color selections and styles are chosen for the entire winter season. The arrangements last through to spring due to the materials chosen, the durable installation technique, and the use of anti-desiccant spray.
For 12 years, Ruth Atzinger has put together wonderful annual potting arrangements in late May or early July. The three elements of a successful arrangement are thriller (upright), spiller (trailing), and filler (colorful mortar to the joints). In 2018, Ruth Atzinger attended a course with Deborah Silver of Detroit Garden Works to learn how to take those techniques from summertime pots to winter potting arrangements. Here is an example of how we have adapted these techniques.
1. Create the Form
Dry floral foam is only 2" thick max. We want 2" of foam below and 2" above the top rim of the frost-resistant or non-ceramic pots we've chosen. This allows for greens to be inserted horizontally into the edge of the foam, giving more fullness to the arrangement. Therefore, foam must be pieced together with hot glue before being cut to size for a tight, snug fit so that the arrangement stays in place through the winter.
2. Cut a hole for the centerpiece
A vertical (thriller) centerpiece will be lashed together with zip ties to a bamboo stake. Mulch or sand is put into the bottom of the pot for two reasons - 1) to gain a lower center of gravity so that the arrangement doesn't blow over in the wind, and 2) to provide material that the centerpiece can be pushed into, stabilizing the centerpiece. In order to make room for the centerpiece, cut a hole in the foam. Wear a dust mask - do not breathe in foam particles.
3. Add Greens
Source fresh cut winter greens such as boxwood, hemlock, thuja, noble fir, or juniper. Sharpen or lightly whittle each cut stem so that the stem fits snugly into the form. Start from the base and circle round and round until the center is reached. Do not skimp on material used. Select a secondary material towards the center of the arrangement for interest. Magnolia or eucalyptus are good choices.
4. Create the Centerpiece
Choose interesting, colorful branches or branches with interesting structure and texture that can be added as is or spray painted. Accent colors with a light spray of reflective spray paint. Cut a length of bamboo that will go to the very bottom of the pot but not be visible above the greenery. Range the centerpiece material around the bamboo and tie with zip ties tightly. Use more material than you think is necessary for a large, voluptuous centerpiece scaled to the size of the pot.
Fill the bottom of the pot approximately 1/3 full with mulch or sand. Then, set the foam form firmly into the rim of the pot. Once in place, insert the separate centerpiece into the hole in the foam, setting the bamboo stake into the mulch. Ensure the centerpiece is strait and set firmly. If a plastic or frost proof pot is used, water can be sprayed into the mulch so that freezing temperatures will set the centerpiece more firmly in place. Ceramic pots could freeze and break.
Anti-desiccant spray such as Wilt-Pruf should be sprayed over the arrangement. This prevents the greenery from drying out and helps to keep the color. Spray to the point of dripping.