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Growing Agapanthus (African Lily) Where Winters Are Cold

agapanthusPURPLE - Nov 2016
Agapanthus in dark purple

Species of the genus Agapanthus (sometimes commonly called African lilies) are favorite perennials in many parts of the world where winters remain mild. In these regions (hardiness zones 9 to 11), all these plants need to give a long-lasting display of beautiful blue, purple, or white flowers is moist, well-drained soil and plenty of sun. But alas, not all of us live in frost-free areas, so if we grow Agapanthus, we must protect it during winter. A greenhouse is ideal for doing this. Simply put the plants in pots and move them into the greenhouse come fall.

Some knowhow is needed when transplanting Agapanthus, starting with preparing the pots and soil. Avoid under-sizing the pots. These plants do best in pots that are about 12 inches or larger in diameter. Also use a good quality potting soil that isn’t too acidic. Only the species A. africanus likes acidic soil, such as a peat-based one. Finally, for better drainage, I add about 25% sand to the planting medium.

Once the pots and soil are ready, following a few additional tips will help the transplants to flourish. Because Agapanthus has thick, fleshy roots that can easily break, take care when handling them. Ideally, you should divide the roots after the plants have finished flowering. There is no need to trim the leaves at this time.

Just remove the yellow ones. By leaving the green leaves intact, the plants

Agapanthus in bloom in the greenhouse - Nov 2016
Agapanthus in Roger’s greenhouse

will continue to store energy for next season’s blooms. Water the plants well after transplanting; then maintain a moderate level of moisture. These plants will rot if overwatered, and they’re unlikely to bloom if allowed to dry out too much. Initially, you should apply 10-10-10 liquid fertilizer every other week. During the winter months, however, cut back on both fertilizer and water. About one-third to one-half of summertime watering is best.

Temperature and sunlight are also important. These plants may not flower if they get too cold over the winter. About 40 degrees F (4o C) is the lowest temperature to allow. On the other hand, if kept too warm during the winter, the flowers sometimes grow well down in the leaves instead of projecting above them. Also don’t keep Agapanthus in too much shade in the winter greenhouse, or that, too, can inhibit subsequent blooming. I keep mine near the back of an attached, heated greenhouse, and they seem to like it there.