The biggest problem with planting vegetable and other seedlings, is watering. Without good watering, the seedlings will suffer transplanting shock and stress, which can easily set them back a few weeks or worse still - result in their death!
All plants that have roots, have minute root hairs - invisible to the human eye - which are responsible for the uptake of life-giving moisture for the seedling. Root hairs are always damaged in any transplanting operation, but anything you can do to minimise this damage, will result in a healthier plant establishing quicker.
Vegetable seedlings should be well watered a few hours before being transplanted. This will help to ensure that the seedling has moisture within its system, to help it get over the shock of transplanting in the early stages.
Make sure that the planting hole is big enough to take the seedling plant without having to force it into place. If the ground is very dry, then also water the planting hole before planting, but if the soil is visibly moist, there is no need for this prior watering. It is very important that soil is then placed back in the hole around the planted seedling and firmed down gently to ensure that the vegetable seedling is firmly set in its new home in the garden.
Small pots - and a watering can. Both are great things to help vegetable seedlings to survive, then thrive.
After planting is completed, water the seedlings with enough water to help the soil settle around the root system.
It is far better to transplant seedlings in the evening rather than morning. This will give the newly planted seedling twelve hours or so before the drying sun and breezes can unsettle it. There are fewer breezes in the night! If the new seedling is planted at the start of the day - especially if hot or breezy - then it is more prone to transplanting shock than if planted in the evening.