What is the difference between a seedling and a transplant?
We get this question a lot, and so we’ve set up this page to hopefully answer the question once and for all [probably not!].
The difference between a seedling and a transplant is that transplants are simply seedlings which have been “transplanted” back into the ground in a controlled growing environment, and allowed to grow for another year or two. An evergreen transplant is therefore much larger and much more robust than an evergreen seedling, and has a root system which can reach much deeper for water. The larger and more expensive transplants are better able to survive field planting and moderate drought and heat than the much smaller and cheaper seedlings. However, the much larger size of these roots make transplants more physically challenging to plant. The easiest type of evergreen tree to plant is called a plug seedling, which has a very predictable “factory style” root system much like a flat of flowers, and can be planted using a garden auger
Seedlings are smaller and cheaper than transplants, and will need supplemental water and TLC during the first growing season. This is especially true if it is hot or dry, or if weeds try to take over. Once a seedling has been dug up, shipped and “transplanted” [see what we did there?] for a year or two, seedlings ARE transplants.
In a nutshell, it is more work initially to plant transplants, but it is more work to care for seedlings later when the heat and dry weather of summer arrives. The larger and husky are transplant tend to fend for themselves much better. However, even transplants will need supplemental water in the first season if you experience moderate drought or above average heat. Evergreen trees need water not just to grow, but also to moderate their temperature via transpiration of water [USGS web site], analogous to how we humans sweat.
There are more detailed descriptions of evergreen seedlings and evergreen transplants if you scroll down a bit on each page.