To keep your primrose blooming inside as long as possible you should keep it in a cool place with bright, diffuse light. This could be an east or north facing window, also on a table in a bright room is a good place. Make sure it does not dry out completely, these are shade-loving, spring plants, meaning they really like their water! You will want to fertilize your primrose regularly to ensure it has lots of reserves for when you plant it outside. To keep your primrose looking great and blooming you should remove any “spent” flowers. Simply use your finger nail and snip of the stem of the flower as close to the base as possible.
Once your primrose ceases to produce blooms you should maintain the same care schedule. Make sure it is watered, fertilized and any dead leaves are removed. You will keep doing the same care until the weather outside improves enough to plant your primrose in the ground. A good indicator of when to plant your primrose outside is when at least 2 different kinds of bulbs have sprouted (generally the first to sprout are crocuses and grape hyacinths) and the evening temperature is steadily between 0-8 ºC.
You will want to choose a place that is out of direct, hot burning sunlight for your primroses. If you choose the correct spot you will likely see them bloom again this fall.