The best way to grow hollyhocks in a garden is to sow seeds where they are to grow, so transplanting issues are never encountered. The seeds may be sown in spring or summer to produce a leafy rosette of leaves that overwinters. In the second year of growth, hollyhock plants produce the tall flower spike. Butterflies and bees pollinate the large flowers, resulting in numerous seeds that fall to the ground and germinate in summer. The perennial plants die back in winter and again sprout and bloom the following late spring or summer depending on climate.
For the highest rate of success of transplanting hollyhocks, they must be dug up and replanted when small. Larger sized hollyhocks have such deep and sparse roots that digging destroys the root system and the plant dries up after transplanting. The best time to transplant seedlings is in late summer or early autumn, when the seeds that dropped earlier that summer sprout and produce seedlings that are about 3 to 6 inches tall. Only focus energy on digging up and moving small hollyhocks that display two or three leaves. Do not count the two embryo leaves that first emerge from the soil in this leaf tally.
When hollyhock seedlings are the proper size, success in transplanting is quite high. Use a large garden shovel and slice into the soil about 6 inches away from the seedling's stem all around it. Lift the root ball in the shovel's blade, trying to preserve the mass of soil around the roots. Immediately plant the root ball in the new planting hole. Once planted, the root ball of the hollyhock seedling needs to be at the same depth in the new planting hole as it previously grew.
Deeply water the transplanted hollyhock seeding to diminish any transplant shock. Don't be alarmed if the plant still wilts after watering. Monitor the transplant daily for the next week, adding water daily to maintain an evenly moist soil. If weather is unusually hot or dry, shade the wilting seedling from midday sunshine. Trimming of oldest, dead leaves may be required. By the time fall starts and cooler temperatures dominate, chances are the roots are again well-established, and the transplanted young hollyhocks are well-prepared to overwinter and grow larger to bloom next year.