One of my favorite times of the year is midsummer when my agapanthus begins to bloom! I just love the almost unique globe-shaped look of the flowers. But what do you do if yours isn’t blooming?
I’ve been growing agapanthus for many years, and I’ve learned many tips, tricks, and secrets for diagnosing why it isn’t blooming and what you can specifically do to get it to bloom the following year.
Let’s cut to the chase!
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.
In my experience, the reasons agapanthus does not flower are not enough sunlight, boggy soil, frost-damaged flower buds, too much nitrogen, or transplant shock due to recent planting, potting, or division.
We need to remember that to get our agapanthus rhizomes to grow and produce the flowers we all love, agapanthus requires full sun, well-draining soil, protection over Winter, and time to establish after planting to display flowers.
Keep reading to learn my methods for pinpointing the problem of why your agapanthus is not flowering and how to ensure agapanthus flowers the following Summer…
Why is My Agapanthus Not Flowering after Planting, Potting, or Dividing?
So I’ve seen this first hand, but it’s good to know that the research matches up with my own experience! 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.
I thought at first I had damaged my agapanthus every time I divided and repotted, which made me anxious!
To properly understand this, we need to appreciate how our agapanthus grow in their natural habitat.
Most gardeners (myself included) cultivate their agapanthus outside of the ideal South African climate and conditions, so it can take the plant a while to adjust to its new settings.
From working in the industry, I know that agapanthus is usually grown in a temperature-controlled greenhouse under optimal conditions before you purchase the plant.
Why does this affect things? Well, the contrast between a greenhouse with controlled conditions and your garden can be quite a shock for the agapanthus, which can prevent it from flowering.
We also need to be aware that agapanthus has a strategy when you replant them! In the first year of planting, most of the plant’s energy is directed into growing and establishing the roots in the soil and growing its lush green foliage rather than displaying flowers.
So, is your agapanthus foliage healthy but without flowers? This is why!
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.
Pro tip: I have personally had much more success dividing and repotting in the Spring, with most of my agapanthus able to flower in the first year, compared with dividing and repotting in the Fall, which, in my experience, often doesn’t flower well the following year. Other keen gardeners I’ve spoken to have experienced the same.
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.
So I have done some testing of my own, and what I’ve discovered is that if you 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. I personally have found a comfrey feed the best for this, although liquid seaweed also works very well!
Watch this YouTube video for a visual guide to the best practices of re-potting and dividing agapanthus:
Are Your Rhizomes Frost Damaged? Protect the Rhizomes in Winter
Remember how we talked about where agapanthus grows in its native environment? Well because of its South African habitat, 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).
It’s also surprising to note that the flower buds for agapanthus are formed in the Fall, and the flowers are displayed the following year. The foliage dies back, but the flower buds are formed near the base of the rhizome in the Fall, ready to grow the following year.
Do you live in a climate that experiences freezing temperatures? I do, too. In cold environments, the flower buds are susceptible to frost damage which prevents the agapanthus from forming flowers in the following Spring.
The solution: The best way that I’ve found to prevent agapanthus flower buds from suffering frost damage is to plant them in pots and move them to a sheltered, frost-free place (such as a greenhouse).
I have personally used a shed before, which worked great. Of course, once the foliage has died back for that year, the agapanthus doesn’t need direct sunlight, so a shed works well.
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.
What I typically find has worked is using a 4 layer of thick fleece that I pin down with tent pegs!
With insulation from the cold, the flower buds remain intact over Winter, and your agapanthus can display the flowers in the Spring. From my experience, the agapanthus itself can often survive freezing temperatures, but the flower bud is more cold-sensitive and dies back, preventing flowering.
However, I took a cold-damaged agapanthus and protected it well the following year. It was then able to flower, so do not give up on your agapanthus!
Use a High Potash Fertilizer to Encourage more Agapanthus Flowers
I got an email from a reader that said…
“I can’t figure out, why my agapanthus isn’t flowering? I have used a lot of fertilizer and watered it really well…”
Have you used any fertilizer on your agapanthus? Heavy-handed use of fertilizer can cause agapanthus to grow more foliage at the expense of flowers, which is a classic mistake I see people make, including the reader. Don’t worry, though; we’ve all made that mistake at some point!
I should say first of all that it’s important that you avoid using high-nitrogen fertilizers (as this results in agapanthus with lots of green leaves and no flowers), and if you are going to use a fertilizer, 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. For these reasons, I have personally experimented with using liquid seaweed, which is a recommendation from famous British Gardener Monty Don, and to be honest, I find it works better than the commercial Miracle-Gro fertilizer I was using.
Here is My secret success tip for fertilizing agapanthus so that they flower better: Agapanthus develops its flower buds from around late Summer or early Fall. Keep using liquid seaweed feed on your potted agapanthus all the way up until the point the foliage dies back. Why? Because even though the agapanthus may have finished flowering, foliage is still going to be photosynthesizing and storing energy in the rhizome to full next year’s growth. This fuels the growth of the following year’s foliage and flowers, and my agapanthus has bloomed much better!
A high potash fertilizer helps to encourage the development of flowers.
Is Your Plant in The Shade? Agapanthus Prefers Full Sun for Flowering
I always tell people it pays dividends to research where your garden (or houseplants) plants come from before you decide where and how to plant them. I think this exemplifies my point. Agapanthus are drought tolerant and thrive in full sun with at least 6 hours of sun per day in their native South Africa.
So what do we do to get ours to flower? Replicate their natural conditions.
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.
If your agapanthus is potted, this is a very easy solution. Potted plants should be moved to a sunny, warm location if in the shade; however, your agapanthus may be planted in a garden border…In this case, I advise transplanting the agapanthus (ideally in the Spring or Fall) and planting it in a sunnier garden border.
As we discussed, 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
Our agapanthus naturally grows in very well-draining soil in mountain meadows. So how on earth do we recreate this in our gardens?!
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.
I cannot emphasize enough that well-draining soil is key. Agapanthus is very susceptible to rot and fungal diseases if grown in boggy ground. This causes stress and prevents the plant from flowering, so avoid planting agapanthus in heavy clay soil.
Do you have clay soil or just a boggy, low-lying garden? Then, my solution is just to grow agapanthus in pots as clay soil is totally at odds with its natural soil conditions, and, from experience, it is very difficult to amend the soil to the agapanthus preferences if your garden is boggy.
However, I have seen great success amending the soil beforehand in most gardens (that don’t have a lot of clay). 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.
In garden borders, I like to add 30% horticultural grit to the planting area (with the rest being compost). I love to use grit because it creates a more porous soil structure than sand to increase drainage, which keeps the rhizomes healthy during winter.
My advice is that if you live in a cold and wet climate during Winter, agapanthus grows particularly well in pots and containers due to the favorable drainage conditions.
In most climates, potted agapanthus should be watered once a week during the Spring and Summer with a good soak to encourage the roots to establish and keep the plant healthy so it can flower, whereas agapanthus planted in garden soil rarely requires any watering after the first year of planting.
Do you have any questions about your agapanthus or any experience you’d like to share? Are you unsure of the exact reason your agapanthus isn’t flowering? Please leave a comment below, and I’ll reply! I love to hear from you!
Key Takeaways:
- The main reasons agapanthus don’t flower are not enough sunlight, too much fertilizer, damaged flower buds from frost, boggy soil, or stress after planting, repotting, 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 will be displayed the following year.
- Agapanthus grows and flowers best in full sun, with good drainage.