Once the season is over and the decorations are down, you may decide to keep your holiday plants in the hope of having them return to bloom next year. They are houseplants after all and it would be a shame to toss a healthy plant (this particular thought is helpful if you need help convincing yourself to try). With proper care, most seasonal plants will carry on for years to come.
Poinsettia- Once the colorful bracts begin to fade and lower leaves have mostly dropped, it is time to give your poinsettia a severe pruning by at least a third. As soon as new leaves begin to sprout from the bare branches, repot the plant into a slightly larger container with excellent drainage. From this point on, poinsettias generally just require at least four hours of direct sun and water as soon as the soil surface is dry. The complicated part of reblooming a poinsettia comes several months before the holidays arrive. Shortly after Labor Day, you will need to ensure that the plant receives 12 hours of darkness every night, while still growing in a sunny position. Some people accomplish this by moving the plant to a dark room or basement at night and then bringing it back out in the morning. A large box placed over the plant at night will also work (if you can do this without damaging the plant). The bracts that are formed in a home will be smaller than when growing in a greenhouse, but there is a sense of accomplishment in successfully reblooming this plant. Warmer temperatures and lots of fertilizer will encourage larger leaves. The other option is to grow the plant in a room where the lights are generally off in the evenings and see what happens. You will likely get some bracts with little effort.
Amaryllis- If you have a south-facing window and some space, keeping your amaryllis as a houseplant is well worth the effort. Choosing a miniature variety will give you a plant that is a more manageable size, but a large specimen plant of the standard amaryllis can be spectacular. Amaryllis bulbs which are grown in water and waxed bulbs can be very difficult to transition into proper growing conditions, so plan ahead if you want to keep your bulb long term. Amaryllis need at least six hours of direct sunlight in order to thrive. They will survive and bloom with less but expect them to be floppy. Amaryllis are actively growing once the foliage has reached about one foot tall. At this point, they should be watered when dry and fertilized at half strength with every watering. Every fourth watering should be clear water in order to avoid salt buildup in the soil. Once the leaves have matured and there are no new leaves growing from the center, switch to a blossom booster fertilizer to give the bulb energy to form buds. The leaves will begin to yellow naturally mid-summer. At this point, cut back on watering. Completely stop watering when the leaves are more yellow than green. Cut off the foliage after it dries naturally, then store the potted bulb in a cool dark place for at least 8 weeks. At any point after this, you can repot the bulb into fresh soil and start the process over again.
Christmas Cactus- Most likely, the Christmas cactus you purchased is actually a Thanksgiving cactus, so you should expect an earlier blooming next year. Keeping these plants cool and bright for the rest of this season should get you some more blooms through the winter. After blooming, these plants will grow. During the growth period, water when dry and fertilize regularly. Christmas cactus prefer a smaller container, but if repotting is necessary, do it as the plant begins to grow. These plants bloom best when they spend the summer outdoors in the shade. They require little care while outside other than watering and occasional fertilizing. As the weather cools, the plants head into dormancy. Budding is triggered by the shortening days of fall and cooler temperatures. The longer you leave these out, the better they will bloom. Bring in at night if temperatures are going to drop below 45°. Keeping the plant cool and bright in the house will usually extend the Thanksgiving bloom through Christmas.
Cyclamen- Giving these mildly fussy plants lots of light, cooler temperatures, and allowing them to go almost dry between waterings will get them through to spring. At this point, they will begin to yellow and go dormant. As the plant loses leaves, begin to restrict water and stop fertilizing. Set the dormant pot on a cool north-facing windowsill or in a protected location outdoors and water only enough to keep it from shriveling. Cyclamen can hold onto a leaf or two through dormancy but may die back completely. As the weather cools, the tuber will begin to sprout leaves. This is the time to repot. Generally, all that is required is a change of soil and not a larger container. Care should be taken to avoid damaging the tuber or overwatering at this stage. Once the foliage is fully growing and flower buds are emerging, begin fertilizing regularly. A cyclamen is able to live for a few years, but it will likely never reach the glory of season one.
Norfolk Island Pine- This is not a blooming plant, but many are purchased this time of year. These can be challenging in the home, but with proper care can be with you next year. Norfolk Pines enjoy consistently bright light with some direct sun. They should never be allowed to go bone dry or to stand in water. The real secret with this plant lies in keeping them cool in the winter. Hot dry winter air is their enemy. If you have a chilly room with a sunny window, this is where your Norfolk Pine wants to live.
While keeping your holiday plants and reblooming them for next year is well worth the effort, there is no shame in letting that poinsettia go in January and buying a new one next year. Plants should provide relaxation and happiness. If they did that job for a month, that is fantastic!