If you want to grow a variety of plants together, you can order different refill 3-packs and combine them as you wish. Refills last up to two years when stored in a cool, dry place, so feel free to stock up on them!
Great news related to this: currently, we have special combo packs available. These packs feature three different sets of plant refills (9 capsules in all) that play well together, and are being offered for a steal. Check them out here: http://www.clickandgrow.com/collections/all-products.