By David H. Trinklein
The ukulele-playing Tiny Tim may have strummed it best. “Tiptoe Through the Tulips” is good advice for gardeners. Tiptoe through the bulb garden, doing little for bigger, more beautiful blooms next year.
Spring bulbs need some care after their flowers have paled, said University of Missouri Extension horticulturist David Trinklein.
“The question of what to do with the plants after they have flowered is an important one to consider, especially if we want to enjoy them again next year,” Trinklein said.
Spring-flowering bulbs require little care during their flowering season. After flowering, however, the plants need to keep their foliage so that the bulbs grow larger the following year. Leaves feed the bulbs and allow them to store food reserves. Larger bulbs result in more lavish displays of flowers.
Bulbs weaken when leaves are removed prematurely. “It is best to allow foliage to remain on the bulbs until it begins to yellow and die back naturally as the season progresses,” Trinklein said. At Missouri’s latitude, this usually happens in late May or June, depending on the temperature.
Remove yellow leaves as soon as they turn. At this point, a lack of chlorophyll prevents the leaves from making food for the bulb. Trinklein also recommends taking the removed leaves out of the garden to lessen the possibility of spreading diseases.
Gardeners often tie the foliage of bulbs together to neaten flowerbeds or borders and to make room for other herbaceous ornamentals. But leaves tied together do not intercept as much sunlight as those left untied, Trinklein warns. This reduces the amount of food the leaves are able to make for bulb enlargement.
Trinklein recommends removing flowers after they wither. This, too, directs the plant’s energy to the bulb and not to seed formation. This practice is especially important for large bulbs such as hyacinth, tulip and narcissus.
Bulbs need proper nutrition for their spring’s work. Use a fertilizer high in phosphorus and low in nitrogen in early spring, when new foliage appears. A fertilizer such as 5-10-5 applied at the rate of 2 pounds per 100 square feet is a good choice. Many gardeners prefer bone meal. However, bone meal can attract digging animals. Manure is not a good choice unless it has been well-aged.
Whatever fertilizer type you choose, avoid spreading it on leaves or too close to the base of plants, Trinklein said. This prevents burning the leaves.
Sometimes bulbs need to be moved, such as when larger tree canopies prevent bulb leaves from receiving enough sunlight. Trinklein recommends waiting until fall to move bulbs. Spring transplanting often results in weakened or dead bulbs.
When moving bulbs, check the new location for proper drainage. Bulbs planted in wet soils tend to rot. Tight soils with poor drainage can also result in stunted bulb growth.
If bulbs have been forced in pots for indoor enjoyment, remove them from their pots and plant them outside or store in a cool location for fall planting.