hi there- i have a couple of potted agapanthus (very root bound, facing south) that have been with me for 5 or 6 years.
they have only reflowered once.
any advice to get blooms again?
I’m sorry to hear that your Agapanthus (Lily of the Nile) isn’t reblooming for you!
Note that there are 2 types of Agapanthus, deciduous and evergreen. Foliage of the deciduous plants (A. campanulatus, A. caulescens, A. coddii, A. inapertus) will die back in the fall and need a period of cool temperatures and darkness over the winter. Evergreen plants (A. praecox, A. africanus) need no special treatment and are generally treated as houseplants. It is important to determine which type(s) of Agapanthus you have, to ensure yours are being over-wintered appropriately.
Here are links to helpful information about these plants and their care:
- Ask a Master Gardener. Agapanthus
- Ask a Master Gardener. Are agapanthus winter hardy?
- University of Wisconsin – Madison. Master gardener program. Agapanthus.
The following issues are important to consider in order for your Agapanthus to bloom:
- Placement. Come spring, they need full sun, 6 hours of sun a day – as you indicate they are in a south-facing window, this is ideal. It is not clear from the information that you provide if you put the pots out during the summer. If so, when summer arrives, it would be a good idea to place the containers in spots that get both full sun and afternoon shade.
- Enough water. Keep the plant on the dry side until early May.
- Well-draining soil/potting mix. You mention that the plant is root-bound. Is the soil in good condition, or has it compacted over time?
- Fertilizer. Use a balanced water-soluble fertilizer, starting around early April – a couple of applications a month should suffice. If you over-fertilize the plants might get leggy.
- Over-crowding of roots. You may have identified the source of the problem for us! While the plants like their roots to be somewhat crowded, if they are extremely root-bound, as you suggest, it may be time to divide them. Sometimes this will be obvious where there are dead leaves in the middle of the plant, or when they have stopped flowering. The plants should be repotted as needed. This may be every 4-5 years for the evergreen varieties and less frequently (every 6-8 years) for deciduous varieties, although will depend on how root-bound your particular plants might be!
To divide a plant, you may be able to tease the roots apart or, if the roots are very congested, you would have to cut through them. If the latter applies, use a clean, sharp knife (clean with rubbing alcohol) and cut the plant into a few sections, each of which includes a portion of the foliage and roots. Trim off damaged roots and dead leaves. Air these new sections (e.g., on a newspaper) overnight so that a callus forms over the cut areas (if you planted them right away, there is a risk the roots would start to rot). The next day, pot up each section and water thoroughly. This process is disruptive to the plant, and you may find that although the foliage is lush and lovely, the plant will not flower until the following summer or even the one after.
All the best with your lovely plants!