Is there something wrong with your regular garden soil? Lilies don't really require a very rich soil - just one that is very well draining. If you are planting in containers, then a a good quality potting soil with a lot of texture is desirable. Miracle Gro tends to be very finely textured and excessively moisture retentive to be the best choice for bulbs.

I'm not sure of the quality of the soil in my backyard. Do you have any particular brand recommendations for the potting soil for containers? Thank you!

i cant grow them very successfully in my soil, so i use containers/pots. i use topsoil (sifted and bagged, most garden centres/diy merchants have it) and mix in a lot of sharp sand (get it from the building section in b&q , its exactly the same as the sand in the gardening section but half the price)

You never want to use garden soil or topsoil in containers. It just doesn't allow for the required drainage and aeration necessary for growing in containers. It is too heavy and with too fine a particle size. Only used a soil-less potting mix in containers. The Container Gardening forum will give you some great options for making your own potting mix OR you can seek out some better prepared bagged mixes. Fafards' Professional Mix, any of the Kellogg brands potting mixes (Master Nursery, Gardner & Bloome, Kellogg) or Dr. Earth potting mix are decent choices. Bagged soils tend to be regional in nature AFA brands are concerned but you want something with not too much peat or coir but with a high proportion of composted bark and drainage enhancers like pumice, perlite or granite grit.

i use (bought) soil and add plenty of sand, that does the trick and in containers its good to have some weight , it stops them being blown over if you have tall lilies like i do :)