Getting started with shrubs in containers
Id like to grow some shrubs & grasses in containers. We have a front porch/patio that borders a driveway, and I'd like some plants as a visual buffer. As a complete beginner, I would like to ask a basic question that is probably too elementary to be covered here: what kind of soil should I use? I got some plain old clay earth from my waste pile, mixed in some compost from the twp. compost site, some Miracle-gro garden soil, a little organic fertilizer and some potting soil.
The plants are a clematis, which I planted about 2 months ago in a large rectangular cedar box next to a wall & trellis. And just today a kaleidoscope abelia in a probably 10 or 15 gal. tub, and 2 kinds of grasses in probably 5 gal containers. (Lowes is selling shrubs & perennials 75 percent off:)
Then I read a website on the subject, which says you shouldn't use regular soil but only 'potting soil". It says that using plain old regular soil increases the risk of "diseases". (then what about regular plants that you plant in the earth, don't they risk diseases too?) Plus potting soil seems a little weak to me for larger shrubs, as it is very light and substance-less... I thought it was only good for indoor tropical plants.
So, should I buy about 5 bags of potting soil, laboriously try to replace the dirt in my planters with as much potting soil as I can? Or is it too late and are they all going to die?
Also... since these are all perennials, I assume I can leave them out in the winter and treat them as I normally would? We are in southeast PA zone 6a... last year we barely got any cold weather at all.
I can take pictures tomorrow & post them. Any advice for a newbie would be appreciated!