The key is to be generous with your bulbs. For a large mixed pot, plant your bulbs shoulder to shoulder in a smaller plastic nursery pot, and then sink it into a larger container. Then plant the fillers and spillers around it.
Remember how tall your bulbs will get. If you have a deep pot, fill some of the space with pinecones or packing peanuts before adding soil. This not only saves on the amount of potting soil you’ll need, but it also significantly reduces the weight of your container. Choosing a fiberglass pot will also make it more lightweight and easier to move around when necessary.
For the best show, plant lots of bulbs. Place bulbs shoulder to shoulder across the surface of the soil, leaving no space between them. Then top off with more potting soil so the bulbs are just slightly below the surface. Water each container thoroughly, and finish with a layer of mulch such as mini pine bark nuggets. Leave pots outdoors for winter chilling. The more exposure to cold the bulbs get, the better they’ll bloom. In the South, bulbs in containers will bloom better than bulbs in the ground because cold air envelopes the pots, reaching all of the soil.