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After the storm

M. Grabowski, UMN Extension Educator

Strong winds and hail have caused significant damage to plants large and small in Minnesota landscapes. Here's what gardeners need to know about treatment and recovery of storm damaged plants.


Storms often reveal hidden rot that
weakens trunks or large branches.
M.Grabowski, UMN Extension
Storm damaged trees may be unstable and can be a hazard to people and property. Contact a certified arborist to evaluate and treat large trees that have suffered from storm damage.

Smaller branches that have been damaged by the storm, are low in the canopy, and accessible from the ground can be treated by the gardener. Prune off branches that are split, cracked, or torn at a point where the wood is undamaged. A tree will heal over small scattered wounds from hail but severely hail damaged branches should be pruned out. A clean pruning cut at a branch union allows the tree to naturally heal over the wound site. A proper pruning cut does not leave a branch stub or remove bark beyond the branch collar. Painting over pruning wounds is unnecessary unless the tree is an oak tree.

Minnesota is currently in the high risk season for oak wilt infection. Sap beetles are attracted to fresh wounds in oak trees and can introduce spores of the oak wilt fungus, which are attached to their bodies. If oak trees have been damaged in recent storms, prune to remove damaged branches and then immediately paint over the wound with water-based paint, a pruning/wound sealer, or shellac.
Hail damage on hostas.
M. Grabowski, UMN Extension

Flower garden

In the flower garden, broad leaved perennials like hostas were most severely damaged by recent hail storms. Long tears in the leaf are signs of hail damage. The plants will tolerate leaf damage and produce new leaves as long as the growing point of the plant is undamaged. Gardeners can prune out the most severely damaged leaves. Do not remove more than one third of the plants foliage however, as the plant will need energy produced by its leaves to recover and produce a new flush of leaves.

Hosta leaves torn by hail
M. Grabowski, UMN Extension
Stems of annual or perennial plants that have been broken by the storm should be pruned back to the next undamaged leaf. Many flowering plants can produce new shoots from buds on the side of the damaged stem or from the crown of the plant. Annual flowering plants that were broken off at the soil level are unlikely to recover at this point however as the plants are not well established this early in the growing season. These plants should be removed and replace.

Vegetable garden
Eggplant leaves with hail damage
M. Grabowski, UMN Extension

Storm damage to vegetables in the garden will vary based on how well established the plants are. Spring greens like spinach, lettuce, bok choy, and Swiss chard likely suffered torn leaves from hail and wind. Plants will recover as long as the growing point is undamaged. Young newly emerged seedlings may have escaped damage due to their size or have been killed completely by a direct hit. Gardeners should evaluate vegetable plants over the next week. Young seedlings that produce new leaves are likely to recover. Seedlings that fail to produce new growth should be removed and replaced.

The apples will bear scars of
hail damage even at harvest
M. Grabowski, UMN Extension
Transplants with a central stem need to be evaluated carefully. A tomato or broccoli plant will tolerate and recover from tearing of the leaves. If the stem breaks near the soil level, however, it is best to remove and replace the plants. Tomatoes, peppers, and eggplants that suffer a break in the stem higher up may sprout from buds on the side of the stem and recover. Broccoli, cauliflower, and cabbage that lose their central growing point however may recover but will likely produce multiple small heads as opposed one large head. Reseeding of broccoli, cauliflower and cabbage can be done in early July where storms have significantly damaged the spring crop to produce a fall crop.

Disposal of plant material
In Minnesota yard waste cannot be sent to the landfill. Place all plant material in a backyard compost bin or bring it to a municipal compost facility.

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