A. Lack of flowering
can result from any of several causes. The most common is insufficient
light. Even plants which flower in filtered light will not produce many
blossoms when planted in deep shade and may appear leggy or spindly.
Diseased plants, mottled, discolored or with chewed leaves usually indicate the
presence of a disease organism or plant pest. Careful inspection of the
lily will determine if the plant is healthy or if it is appropriate to treat for
infestations. Overcrowding and competition for light, nutrients and water
often decrease flowering. Dividing the clumps in the fall will help to
minimize the crowding and perhaps encourage blooming. Also, plants require
a balanced diet of nutrients such as nitrogen, phosphorous, and potassium to
grow and bloom at peak. Excessive nitrogen from high nitrogen fertilizers
throws off the balance of nutrients and encourages lush, green leaf growth at
the expense of blooms. Fertilize the plants with 0-10-10 in late March and
see if that encourages blooming. As another measure to encourage blooming,
check the soil to insure that it is an acid type soil and is well drained.
(Send a soil sample to your nearest Extension Agency to determine the pH value
in order to be certain that this is not the problem.) Easter lilies and
Madonna lilies will succeed in alkaline soil but all lilies prefer the more
acidic soil. Sulfur and alum will acidify soil. Rotting leaves
should also help.
Determining the type of lily is important but since you indicated that it is a day lily (hemerocallis), I will assume you know that the flower is indeed a day lily and not a member of the lilium family, which does not bloom well in our warm climate in the Galveston area. Lilies need 6 weeks of temperatures at 33 degrees F. in order to bloom. Perhaps you should examine the plant carefully to determine if it is an Asiatic Lily, Oriental hybrid or Trumpet hybrid, rather than a day lily. (Note: lilium does best in Zones 4-8 and hemerocallis can do well in Zones 3-9.)
Day lilies are qualified as evergreen, semi-evergreen or domant. Evergreen types with arching grasslike leaves continue through winter in frost-free climates with the plants blooming in their normal cycle. This is the most frequently chosen by gardeners who know that the heat of the Gulf Coast is pretty hard on other day lily varieties. Dormant varieties require a dormant period brought on by frost in order to bloom, and tend to rot in frost-free climates. Semi-evergreens are between the two and may be evergreen in the warmer climates like the Coastal areas or Houston. The short blooming period of lilies have made them less likely to appear in the far reaches of the Coastal area. However, you can successfully use several varieties for continued summer blooms. Early blooming varieties such as Mary Todd and Bertie Feris and mid-season bloomers like Stella de'Oro, Ruffled Apricot, Double Decker, Fragrant Light, Pardon Me, Prairie Moonlight and Sombrero Way which blooms later in the summer, will keep the garden blooming with some color. Remember, day lilies bloom for only a "day" and the fact that they must have several blooms on the plant usually guarantees some color even though the blooms expire quickly. The lily is frequently not chosen in the Coastal area because of this tendency to produce little color for the space it takes in the garden.
A lily-like plant called the Spider Lily (Galvestonensis) is native to Texas and is one of the most indestructible plants. They are generally hardy and can tolerate the Coastal weather and produce clusters of white blooms. Foliage dies back so it should be grown behind other plants to hide the unattractive foliage during the winter. Another lily-like bloom is Crinum (Amaryllidaceae) which has massive clusters of long tubed, lily-like flowers of white or pink. It blooms March through October and remains evergreen throughout the year. It is easy to grow in this area and is commonly called milk lily, wine lily or swamp lily. It naturalizes well and multiplies. So if you are having no luck getting some of the lilies to bloom in a couple of years, then try some of these more Galveston-friendly varieties and enjoy the blooms!