Why is My Agapanthus Not Flowering?

Why is my agapanthus not flowering

Agapanthus (also known as ‘Lily of the Nile‘ and ‘African Lily‘) is a flowering, herbaceous perennial that should bloom in Summer with large blue flowers.

The reasons for Agapanthus not flowering are due to not enough sunlight, boggy soil, frost-damaged flower buds, too much nitrogen, or because of transplant shock due to recent planting, potting, or dividing.

Agapanthus requires full sun, well-draining soil, protection over Winter, and time to establish after planting to display flowers.

Keep reading to learn why your agapanthus is not flowering and how to ensure agapanthus flowers the following Summer…

Agapanthus Not Flowering after Planting, Potting, or Dividing

Agapanthus often displays fewer flowers in the first year after planting, re-potting, or dividing clustered roots due to transplant shock and potential damage to their roots when dividing.

Most gardeners are cultivating their agapanthus outside of the ideal South African climate and conditions, so it can take the agapanthus plant a while to adjust to its new settings as agapanthus are usually grown in a temperature-controlled greenhouse with optimal conditions before you purchase the plant.

Therefore the contrast from a greenhouse with controlled conditions to your garden can be quite a shock for the agapanthus which can prevent it from flowering.

In the first year of planting most of the plant’s energy is directed into growing and establishing the roots in the soil and to growing its lush green foliage rather than displaying flowers.

Also bear in mind that the optimal time for re-potting is in the Spring before the plants start growing, although it is still possible to successfully divide the plant in the Fall.

Dividing or re-potting in the Spring allows for the agapanthus to start establishing itself whilst the soil is warming up before it has to contend with high Summer temperatures which may make it more vulnerable to drought and therefore the conditions are not ideal for developing flower buds.

Water agapanthus well in its first year and feed it with some potash fertilizer after August to help develop the flower buds for next year, and if the agapanthus is in full sun and well-draining soil it should abundant display flowers the following year.

Watch this YouTube video for a visual guide to the best practices of re-potting and dividing agapanthus:

Protect the Flower Buds in Winter

Most Agapanthus cultivars are drought tolerant but not frost tolerant and they require protection from freezing temperatures during Winter if it is to flower (USDA hardiness zones 9-11).

The flower buds for agapanthus are formed in the Fall which then display the flowers the following year.

In cold environments, the flower buds are susceptible to frost damage which prevents the agapanthus from forming flowers in the following Spring.

The solution: To prevent agapanthus flower buds from suffering frost damage, plant agapanthus in pots and move them to a sheltered, frost-free place (such as a greenhouse).

Alternatively, you can use fleece (available for garden centers or Amazon) that is designed to insulate the plant and keep the cold out so that the flower buds remain undamaged.

If you are planting agapanthus in garden boarders then I recommend a deciduous variety rather than the evergreen as they are less vulnerable to the cold, although it is still important to protect the agapanthus flower buds with fleece or with a mulch such as straw over Winter.

With insulation from the cold the flower buds remain intact over Winter and your agapanthus can display the flowers in the Spring.

Use a High Potash Fertilizer to Encourage more Agapanthus Flowers

Heavy-handed use of fertilizer can cause agapanthus to grow more foliage at the expense of flowers.

Avoid the use of any high nitrogen fertilizers (as this results in an agapanthus with lots of green leaves and no flowers) and use a well-balanced 10:10:10 NPK all-purpose fertilizer at the start of Spring (also follow the manufacturer’s instructions).

The use of fertilizer is usually more important for agapanthus in pots and containers as there is less capacity for nutrients compared to garden boarders (if the planting area has been amended with organic material beforehand).

The key to promoting agapanthus flowering is to use a feed that is high in potash (Potassium) after you deadhead the flowers from this year.

Agapanthus develops its flower buds from around late Summer or early Fall. The developing flower buds have to be protected over Winter so that they can display the flowers in the following Spring.

A high potash fertilizer helps to encourage the development of flower buds so switch to a fertilizer with a higher proportion of potash (available on Amazon or in garden centers) to feed the plant with the right nutrients at the appropriate time.

Use a potash feed after this year’s flowers have faded from August until October (always follow the manufacturer’s instruction) as this encourages the agapanthus to develop more flower buds to be displayed the following Spring.

Agapanthus Prefers Full Sun for Flowering

Agapanthus are drought tolerant and thrive in full sun with at least 6 hours of sun per day.

The amount of sun is directly correlated with the display of flowers so if your agapanthus is not flowering then it may be because it is planted in too much shade or shaded by surrounding plants.

Potted plants should be moved to a sunny, warm location if in the shade, however, agapanthus should be transplanted (Ideally in the Spring or Fall) and planted in a sunnier garden border.

Ideally, you should avoid digging up agapanthus and planting in Summer as the plant requires time to establish, and transplanting in Summer heat can cause the plant to lose water and wilt before the roots have time to establish so they can draw up water.

Watering and Soil Conditions for Agapanthus Flowering

Agapanthus is native to South Africa where it grows in very well-draining soil in mountain meadows.

In gardening terms think of the soil and watering conditions for growing agapanthus as similar to growing Mediterranean plants such as Lavender, Rosemary, and Thyme, with good tolerance to drought and a preference for soil that dries out somewhat between bouts of watering or rainfall.

Well-draining soil is key as they are very susceptible to rot and fungal diseases if grown in boggy ground which causes stress and prevents the plant from flowering so avoid planting agapanthus in heavy clay soil.

Agapanthus requires light friable soil that has ideally been amended with compost and perhaps some sand or grit to improve drainage if you live in a climate with high rainfall.

Agapanthus grows particularly well in pots and containers due to the favorable drainage conditions.

In most climates, water potted agapanthus once a week during the Spring and Summer with a good soak to encourage the roots to establish to keep the plant healthy so it can flower, whereas agapanthus planted in garden soil rarely requires any watering after the first year of planting.

Key Takeaways:

  • The main reasons agapanthus don’t flower is because of not enough sunlight, too much fertilizer, the flower buds being damaged in frost, boggy soil, or due to stress after planting, re-potting, or dividing.
  • Agapanthus flowers in well-draining soil, with protection from frost, and often flowers better a year after planting.
  • An application of fertilizer with a higher concentration of potash (potassium) in August can encourage flower buds to develop which display the following year.
  • Agapanthus grows and flowers best in full sun, with good drainage.

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