From my perspective as a Black-eyed Susan, the very best time for you to undertake this process is when I am dormant. This is typically in the early spring, just as the soil becomes workable and my new green shoots are barely peeking from the ground, or in the late fall after my flowering show is complete and my foliage has died back. During these periods, my energy is concentrated entirely within my root system and crown, not in supporting blooms or extensive leaves. This means the shock of being lifted and separated is significantly less traumatic. You are working with my natural cycle, not against it.
Please approach this step with gentleness. Use a sharp spade to dig in a wide circle around my central clump, ensuring you are well beyond my drip line (the outer reach of my foliage). My root mass is dense and fibrous, and you must sever the longer taproots cleanly. Once you have loosened the soil around me, carefully lift my entire root ball from the ground. A forceful yank can cause unnecessary damage to my structural roots, setting back my recovery.
This is the core of the process. Your goal is to create several new, viable plants from my single clump. You can often tease younger, newer growth from the outer edges of the clump apart with your hands. For the older, woodier center of my crown, you will likely need to use two garden forks inserted back-to-back to pry the sections apart, or a sharp, sterilized knife to cut through the tough tissue. Each new division must have two crucial components: a healthy section of my roots, which are my mouth and stomach for absorbing water and nutrients, and at least three to five growing points (shoots or "eyes") from which new stems and leaves will emerge. Without both, the new plant will struggle to establish itself.
Before replanting my divisions, it is wise to prepare both them and their new homes. Gently shake off excess soil from my roots so you can inspect them. Trim any that are broken, damaged, or excessively long. If my foliage is present, you can also trim it back to reduce water loss through transpiration immediately after planting. Dig a new hole that is twice as wide as my root system and of a similar depth. Create a small mound of soil in the center, place my division on top, and spread my roots outward and downward. Backfill the hole, firming the soil gently around my base to eliminate large air pockets.
The first few weeks are critical for my success. Immediately after replanting, I need a deep, thorough watering. This settles the soil around my roots and provides the essential moisture my damaged root system must now work to absorb. Continue to water me regularly, keeping the soil consistently moist but not waterlogged, until I show clear signs of new growth. This indicates that my roots have established themselves and are functioning properly. A layer of organic mulch around my base (but not touching my crown) will help retain that crucial soil moisture and regulate temperature.
