Most likely, when you think of alliums, you picture those plants with the traditional round, purple flowerheads on long stalks that make borders look amazing in late spring and early summer. Alliums, however, are much more than this.
There are alliums that are white, pink, blue, and yellow. There are some alliums that resemble a fireworks display, and others that resemble knotted dreadlocks.
You can identify that alliums are related to onions, garlic, and leeks by the aroma released when you crush the foliage. This family also includes chives (Allium schoenoprasum), which have delicious leaves that may be sliced and used to salads and dips.
Alliums are a favorite of butterflies and bees, and even the dried flowerheads look lovely in the border or in floral arrangements.
When to plant allium bulbs
The greatest time to plant alliums is in mid- to late-autumn, at the same time as tulips and daffodils that bloom in the spring. Allium bulbs are resilient and can withstand harsh winter weather if they are planted in soil that drains effectively.
Some attractive alliums, like “Allium sphaerocephalon,” flower in the late summer. Most ornamental alliums bloom in the late spring and early summer.
Where to plant alliums
The majority of alliums thrive in full sun and well-drained soil. Tall alliums should be planted in a protected area to prevent the stems from blowing over in high winds. Plant purple-flowered chives (‘Allium schoenoprasum’), which appreciate afternoon shade, or yellow-flowered ‘Allium moly’ in shaded areas.
Tall alliums look great planted in broad swaths or punctuated across a border. Late-summer bloomer Allium sphaerocephalon has gorgeous wine-red flowers that stand out amid the grasses in prairie planting schemes.
Long, slender leaves on ornamental alliums fade back as the flowers emerge. To conceal the waning foliage, place allium bulbs under other low-growing plants.
Planting allium bulbs
- Remove any weeds by turning the dirt over. Dig in leaf mold or compost instead of using manure on heavy soil as this can change the soil’s pH level. Alliums thrive in soil with a pH that is neutral.
- Make a hole that is roughly four times the bulb’s depth.
- Put a bulb in the opening with the roots pointing down.
- Gently compact the earth after filling the hole.
Alliums can also be grown in large pots with soil that is a mixture of grit, John Innes No. 3 compost, and multipurpose compost.
Tips on caring for alliums
- Alliums planted in the ground usually don’t need watering.
- In the spring, alliums grown in containers will require regular watering. However, avoid letting the compost become soggy as this could lead to the bulbs rotting.
- Crushed eggshells around plants, copper tape around pots, beer traps, or wildlife-friendly slug pellets can all be used to deter slugs and snails from eating new spring leaves.
- When the plants are in bloom, spread a general-purpose fertilizer to aid in the development of the bulbs, assuring healthy flowers the following year.
- Once the leaves have withered back, remove them.
- There is no need to deadhead the flowerheads unless you choose to because they still look excellent after flowering has completed. As long as they remain in place at the border, they may be ignored.
- Put pots in a greenhouse or up against a wall of a house in the winter to shield them from the cold weather.
Growing allium bulbs from offsets
Offsets, which are little bulbs affixed to the main bulb, are produced by many allium bulbs. These can either be planted directly in the ground or split from the main bulb and placed in tiny pots to grow on. Before they have developed enough to produce flowers, it will take a number of years.
Wait until the allium plants are through flowering before using a garden fork to carefully uproot the plants and inspect the bulbs for offsets. Replant the bulbs after removing any offsets.
Best allium bulbs to plant
Alliums come in a wide variety, from large to little, with flowerheads that are rounded or exotic-looking twisted. Here is a selection of the most well-liked alliums.
- One of the most well-known alliums, Allium ‘Purple Sensation’ has the traditional deep purple spherical flowerheads on long, robust stalks. 1 m (3.5 ft) high.
- Large circular purple flowerheads up to 15 cm (6 in) across on robust stems that are 80 cm (3 ft) tall characterize Allium ‘Globemaster’.
- As its name suggests, Allium giganteum is a true giant with dense, spherical purple flowerheads on stems up to 1.8 meters (6 feet) tall.
Do alliums reappear each year?
The foliage of the allium often appears at least a month before the flowers do. Some species’ foliage starts to turn yellow and die off before the flowers are fully open. Plant the bulbs with other plants that will obscure the wilting foliage to help mask it. Alliums do well with hosta, astilbe, and perennial geranium.
When your alliums are blooming, you may anticipate seeing a lot of pollinators. Any type of habitat garden will benefit greatly from the inclusion of these bulbs.
Like their relatives in the vegetable garden, alliums hardly ever have insect or disease problems. Rarely do bothersome rats and deer show any interest.
Most alliums are perennial plants. They will typically bloom again if the species you are planting is winter hardy and the bulbs are suitable to the growing environment in your yard.
Caring for Alliums After They Flower
Allium wasted flower heads can be removed or left in situ once flowering is over. The seed heads are viewed as an intriguing decorative element by many gardeners. Depending on your environment, they may persist far into the beginning of the fall.
Large-headed alliums like Schubertii and Globemaster hardly ever produce viable seeds. Purple Sensation and drumstick alliums will reseed if the conditions are favorable. Simply remove the seed heads after the flowers have faded and before the seeds develop to prevent a carpet of tiny volunteers.
There are herbaceous alliums as well as alliums that grow from bulbs, including varieties like Millennium and Summer Beauty. These plants have a big root system and come back every year to blossom.
Alliums that emerge from bulbs require their foliage in order to generate energy for the blossoms of the next year. Therefore, it’s crucial to let these plants die back organically. The leaves may typically be removed with a simple tug once it has turned yellow and dried. Trim off the wasted blooms from herbaceous alliums with hedge shears or scissors once they have stopped blooming. This will maintain the plants’ clean appearance and might promote a second flush of blossoms.
How late can allium bulbs be planted?
Yes! Alliums are annual plants that grow again year after year. Due of their extreme cold tolerance, they can endure most zones’ winters.
Alliums planted in the spring will still blossom, yes. Although the blossoms won’t be quite as big, they will return the next year in full force.
Allium may only grow as foliar growth, with no blooms, or not at all, if you plant it too deeply. To ensure the best growth and lessen the possibility of shallow bulbs being dug up by animals, try to put allium 4 inches beneath the soil surface.
The spring is not the time to transplant allium bulbs. Wait until the end of the summer when the foliage begins to turn yellow so that the plant will be in a dormant state and not be concentrating on new growth. It will be difficult to locate the bulbs if you wait until the stems totally wilt.
When do I plant UK-grown allium bulbs?
Allium bulbs can still be planted for a fantastic spring show. The photographs demonstrate how Alliums, when planted properly, are low maintenance, return dependably each year, and are unquestionably one of the most fashionable plants for a border.
Alliums prefer a sunny location with well-drained soil, therefore they do not do well in wet, marshy soil, especially during the winter when the bulbs may rot. Alliums can be grown in containers for a patio display or placed in the borders if you don’t have the best growth conditions.
A. Moly, a bright yellow variety, and Chives, which the bees love (see second image), both of which grow to about 30 cm, are relatively little and perfect for the front of the border. The bees and we both enjoy eating chives, which make a great edging plant.
The outstanding Allium Cristophii (shown third image), one of the tallest kinds above 1m, and A. Globemaster are two of the taller types.
It is recommended to plant alliums in the first two weeks of October because they require to be planted in the early autumn. Bulbs may be purchased and planted for a lot less money than plants can this spring. As with all bulbs, it is ideal to plant them in pots that are four times as deep as the bulbs themselves.
Unusual variants include Nectaroscordum siculum, which is technically not an Allium but is sometimes sold as one (6th image).
Although most of us don’t have so much space, alliums look fantastic when planted in large groups, as in photographs 4 and 5, which are from an RHS garden. Alliums can be utilized well as a theme in smaller gardens when planted in groups and recurring perhaps 3/4 times. This will give a border true style.
Staking may be necessary for taller varieties, particularly in exposed places. Allium are simple to grow and put on a fantastic display. They offer good value for money because they come back and bloom year after year with little care.
Allium’s leaves are not appealing, especially after flowering, hence historically, companion plants like Achillea Mollis or Euphorbia have been planted with Allium to hide the leaves.
Are alliums winter-grown?
Allium bulbs can grow throughout the winter. Alliums require a sunny location with well-drained soil where the summer months can be used to let the bulbs dry out. In regions where the summers are wet, you can lift the bulbs in the summer and grow them in pots or a bulb frame so they can dry out. Most alliums are extremely resilient and simple to grow.
How to Plant Allium Bulbs:
- In the fall, pick a location with some sunshine and excellent soil drainage.
- Allium bulbs are rather easy to plant. With wiry roots emerging from one site and a spike on the other, bulbs resemble an onion. Plant with the spike facing up and the roots pointing downward.
- When planting bulbs, remember to give them at least twice as much soil above them as their height. For large Allium bulbs, dig a 6 inch deep hole, and for little Allium bulbs, a 4 inch deep hole. Drop the bulb into the hole, and then cover it with soil.
- If you’re planting your bulbs in beds, leave about 3 inches between each cluster of bulbs. You can put the plants a little closer together if you are growing them in containers.
- After planting, irrigate thoroughly to help the soil settle over the bulbs.
- Late Spring will see the start of allium bulb flowering. The plant can take advantage of a warmer rest period after the blossoms fade. Throughout this time of rest, you don’t need to drink a lot of water. As the plant’s leaves begin to wither, you have the option of tidying it up by removing the old ones or letting nature take its course.
Alliums can I plant in December?
You must take care to bury the bulbs deeply enough to avoid the wind from knocking the stems down because taller alliums have quite a wide surface area. Typically, you should space your bulbs at least 4 inches apart and plant them at a depth that is four times their diameter. Mark the location of the bulbs by firmly compacting the ground there.
Since alliums are such a sturdy bulb, planting them in December shouldn’t be an issue as long as you avoid doing so during harsh frosts. It is preferable to plant allium bulbs in the autumn, from September to the middle of November. Plant your bulbs as soon as you can after receiving them because otherwise, they can start to dry out.
How are alliums prepared for winter?
Post-bloom maintenance for alliums is quite simple. Simply continue to water the plants sparingly until they start to shrivel and turn yellow. At this point, you have the option of either dividing the plants or cutting them all the way to the ground.
Divide allium bulbs every three to four years. Simply use a shovel to dig around the plant and lift the bulbs out. You should see a group of bulbs that you may gently separate with your hands. Replant a few in the same location, and immediately transplant the others to different sites.
It’s considerably simpler to take care of allium bulbs that you don’t wish to divide. When the foliage starts to fade, simply trim it back, and in the fall, mulch the soil with 2 to 3 inches (5-7.5 cm) of material. In the spring, remove the mulch to allow room for fresh growth.
What happens if alliums are planted too late?
Q I’ve discovered several forgotten spring-flowering bulbs. Does it still make sense to plant them?
A Which? Gardening magazine investigated this question by planting six popular spring bulb varieties at various periods between mid-September and early January.
A The plants that produced the best results for the early flowering Narcissus ‘Tte—tte’ were those that were planted in early October and spent four weeks in full bloom in March. Despite the fact that the time spent in full bloom was cut in half, we nevertheless achieved good results with bulbs planted as late as December. Plants that were planted in January grew shorter, later, and finished flowering two weeks sooner. With the later-flowering Narcissus ‘Passionale,’ there was even less variation; they all flowered well and for about the same amount of time in mid-April. WHICH? VERDICT OF GARDENING MAGAZINE Early autumn is ideal, although plantings in December can still produce respectable results.
A traditional recommendation is to plant tulips in mid- to late-autumn, later than other bulbs, to lower the chance of tulip fire. We found that plantings in late October and November had the optimum emergence, flowering time, and flower quality. With tulips planted in September and the first few days of October, we had losses of up to 25%. The bulbs held their shape well and did not sprout. Early “Red Riding Hood” tulips, on the other hand, blossomed later, were shorter, and spent less time in full bloom after being planted in December and January. Although they flowered for a shorter period of time, May-flowering ‘Queen of Night’ was least influenced by delayed planting. WHICH? VERDICT OF GARDENING MAGAZINE Planting late-flowering types can be put off until late October or early November.
A Crocuses planted in early October compared favorably to those planted in September. The majority of the corms spent a month in full bloom starting in mid-February, and almost all of the bulbs sprouted. The whole flowering period lasted 63 days. Bulbs that were planted later began to bloom later, reaching their peak in late February or early March, and only lasted a fortnight in full bloom. The crocus corms began to sprout in early October, even though they stayed solid until January. Only 60% of the crocus that were planted in January survived, and their blossoms also weren’t as impressive. WHICH? VERDICT OF GARDENING MAGAZINE For a robust and early display, plant in September or early October.
A Muscari bulbs planted in September and early October maintained leaves throughout the winter and produced the best flower display toward the end of March, lasting five weeks at full bloom. If stored for a longer period of time, the bulbs produced some roots and shoots, but bulbs put later survived just as well as those planted earlier. They put on a fantastic display that lasted for four weeks until the beginning of April, growing to roughly the same height and flowering nearly as well as previous ones. WHICH? VERDICT OF GARDENING MAGAZINE As there is no impact on flowering time or flower quality, you can plant whenever you like.
A The longest total flowering time of five weeks was achieved by alliums sown in September, which blossomed in March and spent two weeks in full bloom in May. Bulbs planted after that lasted a week less in bloom, but the displays were still impressive and the blossoming time was only postponed by one or two weeks. The bulbs started to show signs of mold in October, and by January, they had grown tiny shoots. Though later planting didn’t appear to have a negative impact on the quality of the blooms, emergence was good. WHICH? VERDICT OF GARDENING MAGAZINE Although September is ideal, alliums from later plantings continue to bloom well.
A Irises planted in September and early October provided us the longest total flowering durations of eight and seven weeks, as well as the greatest quality flowers. All of the irises we planted were in full bloom for two weeks. Bulbs held their shape but started to sprout in November, making them a little more difficult to plant by January. From November plantings on, fewer bulbs emerged, and they flowered later. Irises planted in December and January were up to 25% shorter than those planted earlier, and the flower spikes bowed rather than rising straight. WHICH? VERDICT OF GARDENING MAGAZINE For strong displays of early color, plant in September or early October.