In the summertime it is critical that you put seedlings into the yard or garden on a cloudy day, in the late afternoon or early evening. The transplanting process is hard enough on the plants without their having to cope with bright, hot sun on their first day in the ground. Do everything you can to minimize damage to the root system of each seedling, and to reduce any other unnecessary shock to the plants.
Dig a hole big enough to contain the root ball and deep enough so the plant is settled in at about the same level it rested in the container. Pour a little water into the hole before placing the seedling. After all the seedlings have been set, give them a thorough watering, without drowning them. A little seaweed extract in that water can help minimize transplant shock.
Another Trick – there is now on the market a new microbial soil amendment product that actually replaces soil microbes that are usually absent from most home landscape soils in this country. A half a teaspoon of this powder in each planting hole is going to give the plants a better chance for long term health.
Yet One More Trick – Most garden centers now sell a material called “shade cloth”. It is fine netting designed to reduce the amount of solar radiation on a plant by a fixed percentage; e.g. 80% light, 60% light, etc. You will be much more successful if you cover your new summer transplants throughout the summer with this shade cloth. The plants will be happier and more healthy.