When it comes to gardening, there always seems to be something new to learn. Even experienced gardeners may not know what to do with alliums after they have flowered. If you’re wondering the same thing, don’t worry – you’re not alone! Although alliums are not particularly high maintenance, learning what to do with allium bulbs after flowering will ensure that they return to brighten up your garden year after year.
What are Allium Bulbs?
Allium bulbs are the bulbous underground storage structures of plants belonging to the Allium genus. This genus includes a wide variety of plants, many of which are commonly used in cooking such as onion and garlic.
- Diverse Genus: The Allium genus comprises over 700 different species, making it incredibly diverse.
- Culinary Varieties: Some of the most well-known Alliums include onions, garlic, shallots, leeks, and chives. These plants have been cultivated for thousands of years for their flavourful bulbs and leaves.
- Ornamental Varieties: Ornamental alliums are prized for their tall stems and large, globe-like flower clusters that can range in colour from purple and blue to yellow and white. They are often used in gardens for their ability to attract pollinators.
- Growth Habit: Allium bulbs typically sprout in the spring, producing tall stems and flowers, and then go dormant in the hotter summer months. The foliage dies back, and the energy is stored in the bulb for the next growing season.
- Health Benefits: Many culinary Alliums are not only valued for their taste but also for their health benefits. They are known to be rich in antioxidants, have anti-inflammatory properties, and can contribute to heart health.
What to do with Alliums after Flowering?
With minimal effort, these perennial beauties can grace your garden year after year.
1 – Removing the Spent Flower Head
- Once the allium flower has lost its lustre and begins to fade, it’s time to act. Gently snip off the spent flower head and the stem.
- Why is this important? Post-flowering, plants will divert their energy towards seed production. By removing the faded bloom, you’re ensuring that the allium redirects its energy towards strengthening the bulb instead.
2 – Leave the Foliage in Place
- While the flower head might be gone, the green foliage still has a crucial role to play. Ensure you leave it untouched.
- The green leaves are the plant’s solar panels. Through the process of photosynthesis, they capture sunlight and convert it into essential nutrients. These nutrients are then stored in the bulb, setting the stage for next year’s growth and bloom.
3 – Let Nature Take Its Course
- Over time, the green foliage will start to yellow and wither. There’s no need to intervene during this phase. Let the leaves die back naturally.
- Once the foliage has completely died back, and the bulb enters its dormant phase, your work is essentially done.
- The dormant bulb doesn’t require watering. However, come early spring, a light application of fertiliser can give it the boost it needs to kickstart the new growing season.
How to Lift and Divide Allium Bulbs?
Every 3 to 4 years, allium bulbs will self-propagate into clusters that can be separated to form new bulbs.
Steps 1 & 2 – As Above
Steps 1 & 2 are the same as above. You will want to ensure that you remove the stem and deadhead the flower but continue letting the foliage continue to grow and absorb sunlight, therefore, refuelling the bulb’s energy stores.
Step 3 – Lift Your Bulbs
Once the foliage has all but died back, you can lift your bulbs. Dig an area around the bulbs being careful not to scratch or scar them as this open wound can leave your bulb susceptible to disease and rot.
Step 3 – Clean Your Bulbs
Once your bulbs have been lifted, they will require a clean. It is best to do this with a soft brush. Gently shake off any excess soil and then using a soft brush, give the bulb a gentle clean.
Step 4 – Divide Your Bulbs
Once you have lifted your bulbs and brushed them off, you will see where the new bulbs have formed, and you will be able to just gently break these apart with your fingers.
Important: It is best to replant all of your bulbs old and new immediately in the places you wish them to grow next year.
How to Store Allium Bulbs?
Storing allium bulbs correctly is essential to ensure their viability for the next planting season. Proper storage prevents rot, keeps the bulbs from drying out, and ensures healthy growth when they are planted.
Lifting the Bulbs
- Wait until the foliage of the alliums has turned yellow and withered. This indicates that the plant has completed its growth cycle for the season.
- Gently dig around the base of the allium plant using a spade or fork, taking care not to damage the bulbs.
- Lift the bulbs out of the ground and gently shake off any excess soil.
Cleaning and Preparing
- Remove any remaining soil clinging to the bulbs. You can use a soft brush or your hands.
- Trim off any remaining foliage, leaving about an inch or so of the stem attached to the bulb.
- Lay the bulbs out in a single layer in a dry, shaded area for several days to allow them to air dry. This process, known as “curing,” helps to toughen up the outer skin of the bulb and reduces the risk of fungal infections during storage.
Note: Examine each bulb and set aside any that show signs of damage, rot, or disease. Only healthy bulbs should be stored.
Packing the Bulbs
- Place the bulbs in a mesh bag, onion sack, or tray. If using a tray, ensure the bulbs are in a single layer and not touching each other.
- For added protection, you can nestle the bulbs in peat moss, sand, or sawdust. This helps regulate moisture and prevents the bulbs from touching each other directly.
Choosing the Right Storage Location
- Store the bulbs in a cool, dry, and dark place. Ideal temperatures range from 2°C to 10°C. A basement, garage, or garden shed can be suitable, provided it remains cool and doesn’t experience freezing temperatures.
- Ensure the storage area has good ventilation to prevent mould and mildew growth.
- Periodically inspect the allium bulbs during storage. Remove any bulbs that show signs of rot or mould to prevent it from spreading to healthy bulbs.
- Ensure the storage area remains consistently cool and dry.
- When it’s time to plant in the next season, take out the bulbs from storage. Discard any that have become soft or show signs of rot. Healthy bulbs will be firm to the touch.
Alliums are extremely low maintenance and do not really take much in the way of looking after them. As long as you let the leaves continue to grow after the flower has gone, they will still be able to store enough energy to flower the next spring. Many people will just mow over the leaves once the flower has gone but this is not a good idea as you will end up with stunted alliums the next spring and that is if they even grow at all. If you need to lift and store your allium bulbs, it is not too difficult either providing you follow the steps that we have laid out for you, you will have beautiful alliums year after year.
Garden Doctor Tips
“Replant stored bulbs in early spring once the ground has thawed!”
“Do not forget to leave the foliage in the ground until it dies back on its own. The bulb needs the foliage for photosynthesis!”
“Over time, allium clusters will expand. Lift and separate bulbs every 3 years and plant a few elsewhere to establish new clusters!”
“If storing bulbs for winter, check on them every 4 weeks to ensure that none of them have rot and gone mushy, if any have, throw them away immediately!”
Frequently Asked Questions
How many years do allium bulbs last?
Allium bulbs do not really like to be out of the ground but those that are in storage and cared for properly will last around 12 months before they require planting.
Do you have to dig up allium bulbs every year?
No, alliums do not need to be lifted every year. Alliums will do fine being in the ground through the winter although it is a good idea to lift bulbs every 3 or 4 years to separate the bulb clusters.
Can allium bulbs be left in pots?
Yes, allium bulbs can be left in pots as long as they are planted deep enough and are protected from heavy frost.
Trevor Wright is not just a seasoned horticulturist; he’s the esteemed Garden Doctor. With a BSc in Horticulture and years of hands-on experience in the soil, Trevor has become a trusted mentor for all things gardening. As the founder of Garden Doctor, he’s committed to clarifying the intricacies of gardening, offering straightforward advice that’s rooted in years of practice. His writing is a garden of how-tos, savvy insights, and comprehensive guides that enable individuals to nurture and grow their garden dreams. When he’s not knee-deep in garden beds, Trevor is at his keyboard passing on his green-thumbed wisdom to budding gardeners, ensuring that the legacy of sustainable and joyful gardening blossoms far and wide.