In the spring. In some mild areas, fall transplanting is fine or even recommended, as trees will not dry out during winter. In areas of very cold and dry winters, however, fall-transplanted trees are likely to be seriously damaged by moisture stresses caused by transplanting and winter drying.
The worst time to move evergreens is right after the season's flush of new growth has begun. This growth is very "thin skinned," leading to rapid water loss, and almost certain dieback.
Evergreens are best moved in the spring.
The best time to transplant evergreens is in the Spring. The bigger the plant the more risk. Keep well watered for a full year after moving.
Summer
Soon after puberty.
The best time is after the first frost and before the last frost of your region. This is because you want to transplant when the plant is dormant.
The best time to plant most trees is during dormancy, so late Fall to early Spring is the best time to plant or transplant hybrid poplars. I feel, if you transplant around December, your trees have plenty of time to get used to their new location before new root, leaf and stem growth begin.
The best time to transplant a peach tree is January. The trees are still dormant from the winter, which will reduce the shock of transplantation. It is also best to transplant a peach tree when it is at least one year old and preferably not after they reach three years old.
Rainy season is the best time to transplant seed. During rainy season, there is a lot of humidity, hence the seed sprouts will get required good quality of water for a better growth.
Spring
Early Spring where I live. Early Spring where I live.
I just read on Fox Hills Lilac Farm's website that the best time is between April and Oct. They stated that 75% are done in the fall.
This is best carried out when the leaves have fallen. With Evergreens do it in the early Spring.