It's already mid-August and while it may still feel like summer where you are, fall and cooler temperatures are right around the corner. Starting about 4 weeks before the first frost is the perfect time to take stock of your perennials and note what is overgrown and what areas of the garden may need a coverage boost. While it may be early, it's time to plan. In short, it's getting to be divide and transplant time.
We recommend this activity when temperatures turn a bit cooler in your area. And as noted in previous tips, we also recommend doing this when that day's temperatures are going to be the most moderate, typically in early evening.
Most gardeners will choose their most robust perennials to divide. Those that have outgrown their current location or are shading other plants from growth are likely to be top candidates. Smaller items like Dicentra, Baptista, Hellebores, and Lavandula tend not to do well with dividing. For those larger candidates, choose healthy plants that can take the stress of a transplant.
Besides transplanting when the temperatures are cooler, ensure your plants are sufficiently hydrated. Water the plant the day prior and the morning of transplant. In addition, soak the new location for the offshoot. Healthy soil is required for the offshoot, so consider amending the new location soil with organic matter.
Lastly, after digging up a perennial, choose small offshoot. For example, about 20% of the original size of the plant. These smaller sections are likely to develop strong roots and grow in seasons to come.