The Chicago Hardy Fig (CHF), a cultivar of the common fig tree (Ficus carica), is prized by northern gardeners for its notable cold tolerance. While it can survive temperatures well below freezing, this resilience requires proper seasonal care. The “hardy” designation means it is better suited for colder climates, such as USDA Zone 5 or 6, than most fig varieties, but it is not maintenance-free during winter. Successfully overwintering this plant requires specific actions to protect its woody structure and root system from sustained frigid conditions. This guide details the necessary process for preparing the tree for dormancy, whether planted in the ground or kept in a container.
Preparing the Tree for Dormancy
Preparation for winter dormancy must begin in late summer, typically August or early September, to signal the tree to slow its growth. Gardeners should cease all fertilizer applications, especially those high in nitrogen, which encourage tender new growth susceptible to frost damage. Gradually reducing the frequency of watering is also necessary to mimic the natural onset of drier, cooler autumn conditions.
The fig tree must be fully dormant before any physical protection is applied, indicated by complete leaf drop after a few light frosts. Allowing the tree to experience temperatures down to approximately 25°F helps properly trigger the dormancy response. Any unripened fruit remaining on the branches in late fall should be removed to conserve the plant’s energy for winter survival. A light structural pruning may also be performed to reduce the tree’s overall size, making the subsequent wrapping process easier.
Winterizing In-Ground Plants
Protecting an in-ground Chicago Hardy Fig is a multi-step project carried out after the tree is fully dormant, usually in late November or early December. The goal is to create an insulated, dry microclimate to shield the sensitive wood and root crown from deep freezes and harsh wind. Begin by loosely tying the branches together with twine to form a compact, upright column, minimizing the surface area exposed and streamlining the wrapping process.
Next, apply a thick layer of organic mulch (wood chips or shredded leaves) around the base, extending out at least 12 inches to insulate the root zone. Construct a protective cage, often called a “fig chimney,” around the tree using sturdy material like chicken wire or metal fencing. This cylindrical structure should stand 6 to 12 inches away from the tied branches to allow space for insulation.
Fill the space between the tree and the cage with dry insulating material (straw, dried leaves, or commercial fiberglass insulation). This material traps air, providing a thermal barrier. Wrap the entire structure tightly with breathable burlap to hold the insulation in place while allowing air exchange. Finally, place a waterproof cap, such as a plastic tarp or an inverted bucket, securely over the top of the cage. This prevents saturation, which would compromise thermal properties and lead to mold or rot.
Winterizing Potted Plants
For Chicago Hardy Fig trees grown in containers, the winterization strategy relies on relocation rather than external wrapping. As soon as the leaves have dropped, move the potted fig to a cool, dark, and sheltered location where temperatures are consistently maintained between 25°F and 45°F. Ideal storage areas include unheated garages, cool basements, or root cellars, as these locations prevent the root ball from freezing solid and suppress premature bud break.
Avoid storing the tree in a space that is too warm, such as a heated living area, because prolonged temperatures above 50°F can cause the tree to break dormancy early. Dormant fig trees require no light. Watering during the winter storage period must be minimal, providing just enough moisture to prevent the fine root hairs from desiccating. Check the soil once a month, applying water only if the soil is completely dry several inches down.
Spring Unwrapping and Reawakening
The spring transition out of winter protection must be timed correctly to prevent cold shock and damage. Begin removing protective layers when the danger of a hard frost has passed, generally in early to mid-March, when nighttime temperatures consistently remain above 20°F.
In-Ground Trees
Unwrapping the in-ground trees should be done gradually over a period of a few days. This allows the tree to acclimate to the increasing light and temperature fluctuations.
Potted Trees
Potted fig trees require a staged introduction to light and warmth. First, move them to a brighter, but still sheltered, location, such as a covered porch or cold frame, before placing them back into full sun. This gradual exposure prevents leaf scorch and thermal shock.
Post-Winter Care
Once fully unwrapped or moved outdoors, prune any branches that appear shriveled, brittle, or black from winter-kill back to healthy wood. This stimulates new growth. A light initial feeding and a return to a regular watering schedule will help the tree quickly recover and initiate the growth cycle for the upcoming season.