While I’ve known intellectually commercial potting soils differ widely, I’ve never really done a side by side comparison. Yes, we went through gobs of potting soil when I had Ashdown Roses but we bought it by the truckload and just used one type all season. We might use a different one the following season but never really compared them.
As you might recall I’ve recently been adding more and more perennials to my rose gardens. This is not only for beauty but also to keep building that “host environment” for beneficial insects. I particularly try to choose those with good nectar as food for the adults and also ones that will provide rough foliage through the winter to house them during the cold season.
Someone sent me some seeds of two types of Salvia Coccinea earlier this year (Thanks!). I sowed them in 72 cell trays. For the soil at this point I actually used very, very old composted manure from the back of our manure pile. Talk about black gold! The seeds sprouted nicely and then it was time to transplant them into slightly larger pots to grow on before putting them in the ground. Considering how hot it is around here at the moment that will be early September, giving them plenty of time to grow.
Eager to get started on the repotting process, I first grabbed a few bags of a basic cheap potting soil. My thought was they are going into the ground eventually anyway so why spring for the expensive stuff. Oops! When I ran out of the cheap stuff I then went ahead and picked up a higher quality with more organics in it and even some time release natural fertilizer. As you can see in the photo there is no contest as to which was better. I’m guessing I don’t even have to tell you which was the better one but just in case it’s the left. Keep in mind this photo was taken only about 7 days after potting them up!
I’ll go back and add some time release to the cheaper stuff but I should have saved myself the trouble.
Which brings me to roses grown in containers. Lots of roses grow great in containers. Floribundas, mini-floras, polyanthas, china roses and all of the smaller shrub roses. Select a container of at least 18 inches (45cm) in diameter and easily just as deep if not more. Roses like deep roots. Whatever you plan to add to the soil you use make sure to spring for the good stuff. Organic with natural organics and even time release organic fertilizer is the way to go. The most important thing is getting your roses off to a great start and in this case when it comes to size soil really matters!