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Potted flowers induce spring fever

Azaleas can rebloom given the proper conditions. (Dave Wallis | The Forum)

By Don Kinzler, Forum News Service

Do you save bread bags, plus the twist ties? Do you collect sawed-off remnants of lumber because someday you might need them for something? Is a corner of your garage devoted to old greenhouse trays, packs and pots because it's a shame to throw away perfectly good growing containers in case you have a bumper crop of seedlings?

Join the savers club -- gardening style. Not only do we hoard pots, we're not about to throw out a once-bloomed plant if there's the remote possibility of coaxing it to reflower.

Garden centers and floral shops are filled with colorful pots of tulips, hyacinths, daffodils, azaleas and hydrangeas. Let's discuss the plants that give us spring fever.

Anytime plants are purchased in spring, they should be wrapped if outdoor temperatures are in the 50s or cooler. Even a quick dash across the parking lot between store and car can result in chill injury if plants are unprotected. Flowers can be damaged even if temperatures are not freezing.

Potted tulips, hyacinths and daffodils are grown from bulbs that have been "forced" into bloom with weeks of chilling followed by warmth and light that mimic the natural outdoor winter and spring cycles.

Can the bulbs be saved and replanted? Potted bulbs won't rebloom as indoor plants, but they can be planted outdoors this spring, if you'd like to save them. It will take a growing season or two for them to become outdoor spring bloomers. Potted bulbs are exhausted from the forcing treatment and will need to replenish strength.

While the plant is still blooming indoors, apply water-soluble fertilizer like Miracle Gro or Schultz once a week following label directions for indoor plants. Remove flower stalks when petals fade, and keep in a sunny window, watering as you would a houseplant.

The key to rebuilding energy in the bulb is to keep foliage green and healthy as long as possible so leaves manufacture food to be stored in the underground bulb as future leaf and flower buds. As leaves begin to turn yellow naturally as weeks progress, gradually discontinue watering. When leaves are crisp and brown, remove bulbs from the potting soil and store in a dry, dark, cool but nonfreezing spot. They can be planted outdoors in spring when soil is workable, or stored dry for midsummer planting. If all goes well, the bulb's leaves will emerge next spring.

Whether they bloom depends upon whether they rebuilt enough strength during the leafy time following flowering. If all you get are leaves, flowering might take an additional year. Remember to fertilize bulbs heavily during the green, leafy stage during and after bloom.

Azaleas thrive in acid soil high in peat moss. They can remain in their original pot for another year, but apply fertilizer labeled for acid-loving plants every two weeks. Azaleas enjoy being kept moister than is healthy for most other plants. Give full sunlight indoors until late May, then give them a summer vacation outdoors in partial shade by sinking pot-and-all into a sheltered flowerbed. Leave outdoors as long as possible in fall so the plant receives the cool temperatures that trigger flower bud formation, but not frost. Bring indoors to a very cool, sunny window with temperatures between 50 and 60 degrees. Keep watered. Buds should swell noticeably by Christmas. Maintain high humidity to prevent bud drop.

Hydrangeas grown as potted flowers are related to the outdoor landscape shrub types, but aren't suitable for our region. After blooming, continue growing in a sunny window, followed by a summer outdoor vacation in partial shade. Keep very moist, and fertilize at least monthly. Allow to receive fall frosts, then store in the garage or other location if temperatures can be kept around 40 degrees for six weeks. Keep moist. Then move indoors to a sunny window. Twigs will sprout new leaves, and blooms will follow in several months.

Cyclamens are grown from a bulb-like corm, which can rot if kept soggy. Avoid getting water in the central "crown" of the plant. Leaves turn yellow quickly if temperatures are too warm and direct sunlight is absent. After flowering, withhold water to induce dormancy. Store pot-and-all in a cool, but not freezing location for about eight weeks. Repot into a peat-based soil mix, leaving the upper half of the corm exposed. Resume watering, and begin fertilizing when growth appears. Locate in filtered sunlight indoors in summer, and increase sun exposure in fall and winter.

(Don Kinzler, a lifelong gardener, worked as an NDSU Extension horticulturist and owned Kinzler's Greenhouse in Fargo. Readers can reach him at forumgrowingtogether//