Can I plant perennials in mulch?

Hi!

I am new to planting. So, I need some advice on plants and mulch. I have 3 ornamental pear trees, probably about 5-8 years old. I put 3-4" of mulch around each of the trees, and now, I want to put plants around each of the trees. Can I plant perennials directly in the mulch, or do I have to plant them in the ground? I'm worried I might hurt the roots of the trees if I dig into the ground.

Type of plants: Hosta, Salvia
Zone: 6 (Western PA)

Any advice would be greatly appreciated.

Although I now live in Southern California before coming here I gardened in Southeastern PA for more than 20 years. I think your perennials will benefit from the mulch. To plant, scrape back the mulch so that you can get to the soil level without mixing the two together. Dig a hole just a little bigger than you perennial plant needs, add the plant to the hole and make sure the soil level of the potted plant is the same as the ground level, back fill with soil tamp in and water the newly planted plant. You may want to water more than once. After the plant has been planted and watered in correctly, move the mulch back to cover the new plant.

Since the trees have been planted over 5 years I am pretty sure they are established and the roots are in good shape. Do not did deep holes all the way around the tree. This could damage newly developing roots. Do not plant too many plants the first year but allow them to grow and fill in. It would be better to plant too few the first year and add more plants in the future to fill in.