Here in California's central valley, we will probably not see much in the way of rain until fall. Our climate is very dry, and very hot. Additionally, my front yard is fairly windy from the canyon-like effect of the street we live on. So it is particularly hard to plant seedlings past early March or so. Even with my clay soil, they tend to dry out too quickly, despite getting spot-watered before and after work.
So this is a trick I've learned to give seedlings a better chance. Maybe everyone knows it already, but I've never seen it mentioned in gardening books.
When I plant a seedling, I set it more or less level with the soil, but I make sure to completely cover the growing medium with native soil. The lovely free-draining nature of seed starting mix means that it works as a great wick for sucking moisture out of the soil if it is left uncovered, which creates a bone dry pocket around the seedling, even if the surrounding dirt is damp. Covering the mix with soil and then watering well helps to seal the moisture in. Of course, some sort of temporary shade shelter can also help.
This is an ornamental seedling that I am protecting with a thin layer of my clay soil.
Hopefully this will work on my late-started tomato and pepper seedlings. The earlier set was smashed by a fallen grow light.
On a brighter note, my oca have started to sprout. I was worried that they might have rotted, but no. Each tuber is now up with a little, clover-leaved sprout.