Why Are My Alliums Not Flowering?

Alliums don’t flower when the bulbs aren’t fully mature, planted in a way that is too deep, overcrowded or kept for too long prior to planting. They also don’t bloom when they are planted in soil that drains slowly and are less likely to flower if they are they are in full shade.

The majority of the causes for non-flowering alliums have in some way connected with the bulb, whether it’s the quality of the bulb or the way they are planted, but there are also environmental factors that could hinder the blooming of alliums.

Continue reading find out the reason why your allium hasn’t bloomed and the best way to fix the issue so that your alliums bloom next year…

Size of Bulb Affects Flowers (Small Bulbs May not Flower the First Year)

The one of the most important factors that determine whether or not an allium is going to bloom within the first year after planting will be the dimension and maturation that the plant has.

It requires a lot of energy to make a plant flower, therefore if the bulbs are small, there’s less energy and resources to flower.

Low quality bulbs or those that are small typically spend their first year switching their energy to growing, adapting to the changing soil conditions and growing properly. They could possibly flower next year when they reach maturity.

The larger, more mature bulbs have a better chance of blooming than smaller bulbs because they have more energy in them that is ready to bloom in spring.

If you’ve planted your allium bulbs and they haven’t bloomed in the first year , they will likely to bloom the following year.

When choosing bulbs made of allium (or bulbs of any kind) at the garden center, ensure that you make an effort to select the largest oldest bulbs to increase the chances of blooming and a healthy plant.

Allium flowers

Planting Allium Bulbs at the Wrong Time Can Prevent Flowering

The best time to plant bulbs of alliums to ensure they bloom is in the autumn in September, and until November while the soil is warm and not yet frozen.

If the bulbs of alliums are planted too late in the season, there is a higher chance of the bulb becoming rotten in the soil and not flowering in the spring.

There is a possibility of planting allium flowers in spring, but they are more likely to channel its energy towards establishing itself in the soil, rather than flowering. However, with patience the allium will bloom well next year since it has had plenty of time to grow.

Bulbs are Too Crowded For Alliums to Flower

One common error when planting bulbs for alliums is to plant them too closely to each other that can stop the bulbs from flowering.

If the bulbs of allium are planted too close, they will have to compete with each other for sunlight, space, water and nutrients which could cause bulbs to not have enough resources to blooming.

To increase the chances of blooming in the coming year, you must remove them and spread the bulbs in a proper way.

The ideal distance for bulbs of allium is approximately 8 inches from each other. At this distance , they are close enough to make an attractive display, but each bulb is spacious enough to provide the necessary resources to flower.

If you think the reason your alliums are not blooming is due to overcrowding, then you should dig the bulbs out (ideally in the fall) and provide each bulb with enough space. The allium will bloom the next year.

Planting Depth of Bulbs can Influence Flowering

The ideal depth of planting for bulbs with allium depends on how big the bulb is, with older bulbs benefiting from more extensive planting while smaller bulbs benefit from relatively shallow planting.

As per to RHS the ideal planting depth is four times larger than the size of the bulb, which typically is around 8 inches or more.

If the bulbs aren’t deep enough, they could be susceptible to damage from frost during the Winter which can damage the bulb and stops the allium from flowering.

Let Foliage die Instead, cut back to Enhance the Flowering

The most common mistake made by the allium (and other plants like Irsis) is to cut back the foliage after they have faded to ensure that the garden boarder appears neater than only the stems and leaves which eventually turn yellow with the flowers die is turned off.

After flowering the leaves of your allium is taking in sunlight to produce photosynthesis, and taking nutrients and moisture from the soil to generate energy. This energy is kept in your bulb to ensure that the next year’s flowers will are able to get all the nutrients they need to grow and blooming in the spring/summer.

The removal of foliage means that there’s little time to allow the bulb’s energy storage within the bulb, so the next blooming could be disappointing or the bulb might not even flower at all.

To ensure the most beautiful possible display of flowers for the coming year, it is recommended to remove the flowers that have faded (so your allium doesn’t burn its energy in producing seeds) and leave the foliage green until it turns brown in the fall or Winter.

The foliage part of the allium will be able to use the fall and summer months to store all the energy needed for next year’s flowers.

Certain gardens suggest that the post-flowering period is the ideal moment to use a fertilizer that is natural, such as seaweed liquid, to ensure that the bulb gets additional nutrients available to grow and matures to show flowers in the next year. However, when the soil is in good condition, it isn’t always required.

When the leaves have died back, it is able to be removed and composted to ensure that your garden boarder appears neat for winter and the next Spring.

Storing Bulbs For Too Long Prevents Flowering

Allium bulbs are brimming with the energy needed to flower.

Bulbs can be kept for a period of 12 months prior to planting, however if they’ve been stored for more than 12 months or kept in less than optimal conditions, then bulbs’ quality may diminish as the resources of the bulb deplete in time, which could hinder flowering.

Allium bulbs which have been stored for long periods of time could require two years of growing before they bloom However, if they are stored poorly they might not bloom in any way.

Bulbs that have frozen during the winter or exposed to heat during Summer while in storage will not bloom.

Allium bulbs should be kept in a cool location like a garage, to ensure they are not in use and will not freeze in the winter or get too hot during the summer months prior to planting (The most ideal time to plant bulbs of allium is in the beginning of autumn).

Be aware that the bulbs could be stored for a while at an outdoor garden centre, so make sure to purchase your bulbs from a retailer with an excellent reputation for quality to ensure that your bulbs will bloom in the very first spring after having been planted.

Too Much Nutrients Prevents Alliums Flowering

Allliums like soil that drains well and not excessively abundant in nutrients prior to flowering. If you add fertilizer or cover the ground with organic matter that is rich in nitrogen (such as manure from poultry) the alliums could be lush with foliage , but not many flowers.

Nitrogen is an essential element for all plants, but excessive nitrogen can encourage growth of foliage, but and can harm flowers.

To prevent this from occurring to your alliums Avoid adding fertilizers to the soil until after the blooming season has ended (alliums bloom in spring and summer, but the their exact timing can differ depending on the specific cultivar and the conditions).

Alliums thrive and bloom best when they are well-drained and soil mixes that are often grittier and compost that is multi-purpose and good.

Thus, a high concentration of nutrients prior to Spring or Summer are not ideal for flower displays.

If you’ve applied fertilizer to your alliums, there’s nothing you can do except reduce the amount of mulch fertilizer, make sure that the soil drains well and wait until the next year, when the nutrient profile of your soil will be more balanced, and the alliums will begin to bloom.

Boggy Soil Can Prevent Alliums From Flowering

Alliums are native to areas that have sandy, dry soils like Central Europe and Persia therefore they require well-drained soil to last through winter without rotting, and to flower during the summer.

In boggy or slow draining soils, the allium bulbs are more likely to decay and never even if they flower. when your soil is…

  • Clay soil that is heavy or compacted.
  • The soil is naturally boggy and low lying.

…then the best choice would be to grow (or transplant) bulbs of allium in containers, pots or raised beds. This will allow you to cultivate alliums to flower.

It’s much easier to make a great potting mix and plant alliums in pots. The next step is to alter garden boards to accommodate alliums.

If you are planting in pots, it is recommended to include a little horticultural sandy or even grit (around 15% by volume) to ensure drainage . You can use the remainder as multi-purpose compost to ensure the best combination of drainage that is good and soil nutrients to allow alliums to show off flowers.

Pots also have the benefit of being portable , so if rain is heavy, you can put the containers and pots under covers to stop the bulbs from decaying in moist soil.

For alliums that grow in garden boarders, it’s recommended to make the soil more fertile by amending by grit or sand to recreate the well-draining, sandy conditions that alliums thrive in.

Not Enough Light for Alliums to Flower

Alliums flourish in full sun and usually bloom best when there is at minimum 6 hours of direct sunlight.

In hot climates or the summer months with intense temperatures, the alliums could be benefited if they are situated within 6 hours of morning sunshine with shade during the afternoon and midday to shield them from the intense heat, which can cause dryness and wilting, which could obviously impact the flowering.

Alliums may flower in shade, but when they are in a shaded area, they won’t bloom at their peak. it is best to transplant them by lifting them carefully using a the fork and locating an area with more sun.

If you can, cut back limbs of trees which may have created an overhanging canopy that casts shade over your alliums. You can also cut back any plants that could be clogging your alliums.

With longer hours of sunshine, the allium is able to use greater energy, and more resources to show flowers.

Drought Can Affect Alliums Flowering

Alliums like soil that is well-draining (it is recommended to sprinkle some grit on the ground prior to plant bulbs in order to guarantee proper drainage of the soil surrounding the bulb) However, they may suffer when there is a drought.

If the conditions are dry for the allium during the spring and summer, the allium might not bloom or show a mediocre display of flowers.

If the weather is dry in the fall, when alliums store the energy needed for the next year’s flowers in their bulbs, this could also hinder a beautiful flower display the following year.

They are easy to maintain most of the time, but when there is a severe drought in the Spring, Summer or Autumn, provide the garden with a good wash every week to ensure that the plants can absorb the water when needed.

Avoid watering in winter because bulbs are in a state dormancy, and excessive water may increase the chance of the onset of.

Potted alliums are more susceptible to drought than bulbs that are that are planted on garden boards. So, water them every week, in dry weather, to encourage flowering in spring.

Key Takeaways

  • The reason that alliums don’t bloom is typically because the bulb isn’t mature, or is planted in a shallow area, or planted in the wrong time of the year. Lack of sun, drought and boggy soil may hinder the blooming of alliums.
  • Alliums need to be planted in a sandy well-drained soil, and must be grown in full sun for enough energy to bloom.
  • The soil which has been altered by manure or nitrogen fertilizer can often encourage foliage growth , but at the expense of flowers.
  • Cut back the foliage too early when it’s still green in the fall and summer months could prevent the allium from providing the bulb with moisture, nutrients and energy to produce next year’s flowers. Cut back the foliage only once it begins to turn brown.


Went from a bad gardener to a half-decent one over 10+ years. Super happy to share my tips and tricks with you :)