Planting impatiens under forsythia shrub

Planting impatiens under forsythia shrub is a great idea as these flowers require shade ( no direct sunlight)
My tips:

1. Water them everyday during hot days 
2. Best to plant in containers as they can be kept indoors during winter. 
3. Provide them liquid fertilizer 10-10-10 NPK every two weeks. 
4. Deadhead spent flowers
5. Water them early in the morning as evening watering will invite slugs and snails.
6. Layer with mulch to keep them moist and with egg shells to repel slugs and snails.