Alliums are one of those plants that offer a huge amount of gorgeousness in return for the littlest amount of effort – you simply put them in the ground and they magically return spring after spring. They are hands down the bulbs that give me the greatest sense of achievement because they consistently provide weeks and weeks of drop dead glamour in the borders. Planted in swathes, their sparkler heads are just spectacular.
From the humble onion family, they are the unlikely sirens of the garden – their globes are held aloft on long, strong stems, and they are excellent for cutting when in flower or as dried, decorative seed pods. You can’t beat alliums for adding late spring and summer pizzazz – explore our range of allium bulbs in all shades of purple, as well as white and blue.
With their beautiful spherical blooms and versatile bulbs, Alliums are a must-have for any garden. However, understanding how to properly water these plants is key to keeping them happy and healthy. In this comprehensive guide, we’ll explore Allium water needs for optimal growth.
Getting to Know Alliums
Allium is a genus of flowering bulb plants that includes popular varieties like onions, garlic, leeks, chives, and ornamental Alliums. They come in a wide range of sizes – from short 6 inch chives to towering 4-5 foot ornamental Alliums. Their water needs vary accordingly.
Alliums thrive in well-draining soil and full sun. Too much moisture can cause bulbs to rot. But insufficient water especially during growth and flowering can cause stunted plants and poor blooms. Finding the right balance is critical.
When gauging Allium water requirements it helps to understand their growth habit and key stages
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Spring Growth – Bulbs send up green shoots and roots. Plants need ample moisture to fuel growth.
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Summer Flowering – Flower buds open into colorful blooms. Adequate water prevents drying out.
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Die Back – Leaves yellow and wilt after flowering. Water needs decrease.
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Dormancy – Plants go dormant over winter. Water sparingly during this rest period.
Water Needs During Growth and Bloom Season
During the active growth and flowering stages in spring and summer, Alliums benefit from deep, thorough watering. Here are some tips:
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Aim for 1 inch of water per week – This can come from rainfall or supplemental watering. Adjust as needed based on climate.
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Water deeply – Moisten the entire root zone, not just the surface. Deep watering encourages deep roots.
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Water at soil level – Avoid overhead watering to reduce disease risk. Use drip irrigation or direct water to the base.
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Water in morning – This allows foliage to dry out during the day, preventing mildew and rot.
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Check soil – Dig down a few inches to ensure moisture is penetrating deeply into the root zone.
Adjusting Watering Based on Plant Size
Larger ornamental Alliums have a higher water demand while smaller chives and leeks require less.
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Larger varieties – Need more frequent watering, up to 2-3 times per week if soil dries out.
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Smaller varieties – Require less watering, even as little as once per week. Rely more on occasional deep soaking.
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Container plants – Dry out faster than in-ground plants. Check soil daily and water when top few inches become dry.
Reducing Water During Dormancy
After flowering ends, Allium foliage starts to yellow and die back as the plant goes dormant. At this stage, reduce watering frequency:
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Taper off watering – Slowly reduce irrigation over several weeks as lower leaves wilt.
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Water every 2-3 weeks – This occasional deep watering keeps bulbs from shriveling.
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Stop overhead watering – Prevent diseases like botrytis during die back.
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Check bulbs – Water again if bulbs start to shrink and papery outer layers emerge.
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No water in winter – Once dormant, bulbs shouldn’t need any irrigation until spring.
Signs of Under or Overwatering
It’s important to recognize symptoms of too little or too much water for Alliums:
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Underwatering – Wilting, scorched leaf tips, stunted plants, poor flowering
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Overwatering – Yellow lower leaves, bulbs rotting, root diseases
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Just right – Steady moderate growth, lush green leaves, large blooms
By tuning in to your plants’ signs and adjusting your watering practices, you can maintain optimal moisture levels for your Alliums to thrive.
Best Practices for Healthy, Hydrated Alliums
Follow these tips for successfully watering your Allium plants:
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Choose well-draining sites with full sun to reduce disease risk.
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Mulch beds to conserve moisture and reduce weeds.
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Group plants with similar water needs for easier irrigation.
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Use drip lines or soaker hoses for efficient watering.
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Water early in the day so plants dry out by nightfall.
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Check soil frequently and water when top few inches become dry.
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Reduce watering frequency as plants yellow and go dormant in fall.
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Remove excess mulch after die back to prevent overwintering diseases.
Understanding your Alliums’ seasonal water requirements ensures they get the hydration they need for robust growth, spectacular blooms, and successful dormancy. A little attention to their moisture levels goes a long way in growing vigorous Alliums.
how to plant alliums
Allium bulbs should be planted outdoors in autumn. Dig a hole for each bulb, or if you are planting lots in one go, dig a trench. I tend to plant in good drifts, rather than in twos and threes to avoid a dotty look. On heavy soil spread a 5cm (2in) layer of grit (or spent compost) over the bottom of the hole or trench. As a general rule, make sure the hole is at least twice the depth of the bulb, and leave a gap of at least 3 times the bulb width between each bulb. For small- and medium-sized bulbs (such as ‘Purple Sensation’), this is around 10-15cm (4-6in) deep and 10-15cm (4-6in) apart. For the larger varieties (such as Purple Rain) it’s around 15cm (6in) deep, but at least 20-30cm (8in-1ft) apart as they need more space for their much larger flower heads and foliage. Giants like ‘Globemaster’ need to be 30-45cm (12-18in) apart to accommodate their gorgeous heads. Place your bulbs on the bottom of the trench/hole and then cover them up – if on very heavy soil, mix in about one-third grit to two-thirds soil to fill in. After planting, firm the ground with your hand.
how to care for alliums
Alliums are drought tolerant so are unlikely to need watering if planted in the ground; they will be watered by rain through the winter. If there’s a long dry spell in April or May, water accordingly, paying particular attention to pots which can dry out quickly.
On poor soil, it’s worth giving almost all spring-flowering bulbs a potash feed in the early spring. This helps feed the bulbs and will encourage them to stick around and flower on and on for years. We use comfrey pellets, rich in natural potash.
Alliums are usually grown for their ornamental heads which look good after they have gone to seed. If you want to minimise seedlings, you can remove the heads before the seeds ripen. All bulbs do best if you minimize the number of leaves you cut when you pick the flowers. As with all bulbs, it is best to leave the foliage to die back naturally so that the bulbs store as much energy as possible for the following year. However, in the case of alliums, if the foliage is really tatty and brown when they are in flower, there is no harm in removing it.
If planted deeply enough, in full sun (so they don’t stretch toward the light), and in a sheltered position (so they don’t blow over in the wind), even the very tallest alliums won’t need staking, as their strong stems can support them.
Over a few years, allium bulbs can clump up by producing offsets, and a drift of alliums can become congested. When this happens, thin them out. When they have finished flowering, lift and divide them. Replant bulbs elsewhere in the garden, or share with a friend.
As well as lifting and dividing alliums, you can propagate the plant by seed – wait until the seedhead is dry and collect the seed to sow immediately or store and sow the following spring. Hybrids won’t be true to the parent plant and it can take several years to reach flowering size.
Alliums are hardy so don’t need any special winter care. If youve grown them in containers, you can move the pots to a sheltered spot to stop the compost becoming waterlogged.
- Early alliums, such as ‘Purple Sensation’, flower in May.
- Enjoy a spectacular show of allium flowers.
- Water during a dry spell, paying particular attention to alliums in pots.
- Plant your allium bulbs in garden borders and in containers.
- If the weather is very cold and wet, bring pots undercover or to a sheltered spot.
5 Quick tips on watering your indoor plants
FAQ
How often should I water Allium?
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Do alliums like well-drained soil?