Second, to protect garden mums from winter damage, wait until the top has been killed by frost. Cut the dead top off at about two inches above the ground. After several hard frosts, cover the plant with six to eight inches of mulch. This stops the alternating freeze-thaw cycles that can kill the roots. Remove about half the mulch in the spring as the new growth begins to grow.
Third, the soil in the flower pot is probably very different from the garden soil. It is likely to just be peat moss and some bark chips or perlite. It will dry out very quickly. Winter air is very dry and even slight winds will dry off the soil. The mulch will help but if there is no snow cover, you may need to water the plants a few times over the winter.
I once planted several species and many varieties of bulbs very late in the fall. There were varieties that were supposed to bloom in early, mid, and late spring. Since none of them grew roots in the fall, they did that in the spring and then they all bloomed at once in late spring.
For most gardeners in northern areas, it is better that the bulbs are in the ground in the fall, even if planted late. Southern gardeners who don’t have cold enough winters to give the bulbs proper growing conditions may buy the bulbs in pots in the spring. Those pots have been kept in refrigerators over the winter.
You can do this yourself. Plant the bulbs in pots with normal potting soil for house plants. The wider the pot, the better. We don’t need a lot of roots like we would for a houseplant, so a shallow, wide pot allows more bulbs to grow in the pot for a better display of flowers in the spring. You can plant large bulbs near the bottom of the pot and small bulbs above them so that there are two levels of flowers. You can plant small bulbs on one side and large bulbs on the other side for a one-sided display. You can plant one kind of bulb in each pot so that as a pot comes into bloom it can be added to the display, and as it goes out of bloom it can be removed.
After it is potted up, water the soil. Since refrigerators dry out everything that is in them, it is a good idea to place the pot in a sealed plastic bag. After at least 90 days, take the pots out and let the plants grow in a bright but cool location. You need to give them spring weather conditions, not hot summer conditions for the best flower display.
