As soon as the trees start growing in your area. And remember with the Wedgle, there is No drilling of trees. Chemical is injected directly through the bark without drilling. No air enters the sapwood so chemical is readily absorbed. The vascular system is undisturbed, maintaining nutrient movement, upward and laterally. The chemical is injected into the cambial zone where the tree can use it effectively. You’ll see improved results from less chemical. Contact your distributor now to order your product and be ready for this year’s growing season. For more information, click here.