Large pots, the bigger the better. The larger the soil volume in the pot, the less chance there is of baking or freezing the bulbs within. This is especially important if the pots are black or dark colored, and they sit in full sun all day.

A good potting mix is:
40% sand
30% peat
30% compost

But I'm sure there are folks out there who have other ideas about container potting mixtures for lilies. Need a good mix that drains well and doesn't turn to concrete over the season.

Make sure there are drainage holes at the bottom of the pot no matter what size, color or shape it is - drainage is the most important element with lilies. Don't settle for a layer of rock or gravel as drainage without several holes.

Water when the soil is visibly dry. Lilies don't like sitting in water and the bulbs will rot.

I've got regal lilies in a pot. The pot is about 20 inches in diameter, I believe, and maybe about as high, or a little taller. I put three bulbs in there about a year and a half ago. I used Miracle Grow potting soil, NOT garden soil. I think the potting soil is a lighter mixture, suitable for plants in containers, indoors as well as outdoors. The pot is basically the same shape as your standard "terracotta" plastic pot you can find in Home Depot, Lowe's, etc, but large, with drainage holes beneath. I think mine came with an attached saucer, but I can't remember... it's attached now, anyways. I was a bit worried because we had so much wet, cold weather, both over the winter and early spring, but they came back, and have multiplied. And they're huge... they're pushing 5 ft now, and I'm starting to see the evidence of buds. They definitely need some support, especially if you have windy conditions. Usually, not so windy here, but we've been getting storms with some pretty high winds, so I'm glad I have them staked.

They are enjoying the patch of full sun I have them in (my concrete yard gets only a stripe of full sun) and I've heard they like to have shadier conditions near their roots, but sunny conditions for the plants. Mine did fine with just straight out full sun, though.

After they're done blooming, just let them be, even though the plant starts looking kinda ugly. This year, I've planted the space around the lily stems with some colorful "filler", so I can have something nice to look at after the lilies are done. Should be fun to see how this works out.

Hope this give you a reference point. I see that you are in NJ, which should be similar to PA, so what works for me could very well work for you. Good luck!

In 5th year w/ lilies in containers. Open ground is rocks & heavy clay. In all cases used commercial soilless mix (like Pro-Mix) w/ added vermiculite & sand. Smaller containers (12-13") get wintered in an unheated greenhouse. Some are in third year and looking strong; more robust than last spring. The large containers mentioned would be better but I can't handle them.

Last Fall, used some 18-gal storage tubs for new purchases. Overwintered these outside but tucked against small woods for protection from wind, etc. While the exterior isn't too classy, the bulbs are coming up like gangbusters. Will mostly be using them for cutting so "class" isn't major. Tubs do take a lot mix to fill.

I put about 5 or 6 Stargazers in a cheap 5-gal white pot. They were spectacular, even better than ones I planted in the ground that I bought in two separate shipments from the same vendor, never saw Stargazers like that.

I used a quality potting soil, oh yes, Canadian Gold. Now I use Miracle Gro because I can get it closer and it's not quite as heavy to carry. I did transplant those lilies out of the pot and set them in the ground last fall, they had a lot of roots I tried to take care about, and they are up and going this spring.

It will be interesting to see if the blooms are as gorgeous as they were in the pot.