Do you want to bring shades of purple to your flower beds and grow a hardy perennial that is easy to manage? Then you may be interested in planting alliums.
In this guide, you will learn all about alliums, including their appearance, blooming season, ideal growing conditions, care requirements, and more.
To get started, we will talk about what exactly alliums are.
Jump to:
- What Are Alliums?
- Allium Basics
- Why Grow Alliums?
- Recommended Allium Varieties
- Where Do Alliums Grow?
- When Do Alliums Bloom?
- How Long Do Alliums Bloom?
- When to Plant Alliums
- Ideal Growing Conditions for Alliums
- How to Plant Alliums
- How to Store Allium Bulbs
- How to Care for Alliums
- How to Divide Allium Bulbs
- Recommended Companion Plants for Alliums
- Frequently Asked Questions About Growing Alliums
- Where to Buy Alliums
What Are Alliums?
The word Allium actually refers to an entire genus of monocotyledonous flowering plants.
You may have heard the word used in a culinary context, not just within the context of growing flowers.
Indeed, garlic, onions, leeks, chives, and scallions are all examples of species in the Allium genus.
In this guide, however, we will be focusing mostly on ornamental flowering plants in the Allium genus such as A. cristophii and A. giganteum.
Alliums are very distinctive. Each consist of a ball-shaped cluster of flowers called an “umbel” on top of a single stalk.
Indeed, the stalks grow directly upward, and the clusters are impressively round, so much so that they have the tidy look of something that was created by man and not by nature—like a ball of cotton candy or a giant lollipop on a stick.
One thing that is important to know upfront about alliums is that they are toxic to dogs and cats.
So, if you have a dog or cat you let out in your yard (or if your neighbors’ pets wander into your hard), you might want to consider a different perennial.
Allium Basics
| Zones: | 3-9 (depending on what type of allium you plant) |
| Blooming season: | May-July (depending on the cultivar) |
| Expected height: | Anywhere from 6 inches to 8 feet |
| Soil: | Rich, well-drained soil |
| Sun: | Partial to full sun |
Why Grow Alliums?
Here are a few great reasons to consider bringing the beauty of alliums to your garden:
The distinctive look of allium flowers is surreal, bringing a whimsical quality to your garden. Alliums are dramatic and eye-catching, and they will be sure to delight you and anyone who happens by your garden.
There are many colors available. While the majority of allium flowers come in shades of purple, there are some other colors you can choose from as well.
Alliums are deer-resistant. Deer do not like allium plants because of how they smell. The same goes for rabbits and most other animals that might get into eating other plants in your garden. So, you should not need to worry about protecting them. Moreover, you can use them as companion plants for other plants you do need to protect.
Diseases and insect pests rarely affect allium flowers. You generally will not need to deal with insects eating your alliums. It is also pretty rare for alliums to suffer from diseases.
These flowers tolerate drought. If you live in a dry climate, you will find that alliums stand up to drought conditions admirably. Indeed, they may do better in a drier climate than they would in one which is on the wetter side.
You can grow alliums in your flower beds or in pots. It is up to you how to grow alliums. You can plant them directly in your garden or you can grow them in containers.
Your gorgeous alliums can come back year after year. As summer perennials, alliums return every year. They are particularly popular for perennial borders.
Propagating alliums is virtually effortless. If you let them go to seed, they will spread on their own. But you should know that growing alliums from their seeds takes longer than growing them from the bulbs. So, just keep that in mind for the coming seasons.
Bees like allium flowers. So, if you are keen on inviting them to spend time in your garden, planting alliums should get them buzzing around.
Growing alliums is easy. Owing to some of the benefits listed above like drought tolerance and deer resistance, growing alliums is easy and requires little in the way of maintenance. So, if you are a novice gardener, these perennials make a wonderful choice.
Recommended Allium Varieties
There are many impressive varieties of alliums out there. Here are some types of alliums you might enjoy adding to your garden:
Allium oreophilum: This dwarf allium variety is the one to choose if you want a plant that is very short. It gets no taller than around 3-6 inches. Its flowers smell beautiful, and are a lovely light pink.
Purple Sensation: One of the best-known cultivars of ornamental allium flowers is “Purple Sensation.” The stalks are sturdy and can reach a height of 24-30 inches. Each is topped with a 2-4 diameter allium globe. They are dramatic and versatile, and can look great anywhere in your garden.
Allium carinatum pulchellum. While most alliums feature dense balls of flowers at the tops of their stems, this cultivar is different. Instead, what you have is a loose ball of bell-shaped flowers that grows upward or droops at an angle from the rest. So, instead of a ball, what you have is an effect that is usually compared to a firework.
Drumstick Allium: One of the most recognizable and distinct allium varieties is the “Drumstick Allium.” The heads have a more oblong shape rather than forming as a perfect sphere. They are a combination of green on the bottom and burgundy on the top.
Golden Garlic (A. moly) ‘Jeannine’: Looking for a yellow allium? These plants grow 8-10 inches tall, and feature lovely yellow blossoms. If you do not have full sun available in your garden, this cultivar may do all right in your partial shade.
A. caeruleum: This allium plant features blue flowers. Indeed, they are actually blue, not just a very cool purple, so they can bring a different color to your garden.
Mount Everest: Unsurprisingly given its name, this plant bears white blossoms. Each ball is 4-6 inches across, so these flowers are massive! The stalks are 3-4 feet high, so you can’t miss them.
A. giganteum: Sometimes simply called the “giant onion,” this cultivar comes from Asia. It reaches almost 5 feet in height, and produces small but dense purple blossoms.
Globemaster: If you are looking for an allium that produces really big flower balls, the one you want is Globemaster. This famous cultivar also produces purple blossoms, but they measure an astonishing 5.9-7.9 inches across.
Allium Hair: This peculiar-looking allium doesn’t produce a head full of flowers, but rather a head full of green “hair.” They will make for a great conversation starter for anyone touring your garden.
Allium Graceful Beauty: Appropriately named, this elegant plant produces a ball with white blossoms, each of which features six pointed petals for a “starry” look. The look is almost reminiscent of ball origami.
Allium Bulgaricum (Summer Bells): The heads of these stalks produce flowers that are bell-shaped and point downward.
Allium Schubertii: Here is a cultivar of allium with a very unusual look. Each ball features tubular florets that protrude way out from the center. This is almost what you would expect a flower to look like from another planet.
Gladiator: Another very popular cultivar of allium is the one known as “Gladiator.” While Globemaster is bigger, Gladiator is still pretty large. Moreover, it blooms starting in late spring and continuing through into the early part of summer. So, you can enjoy it for longer than some other varieties.
Plenty of other types of allium plants are out there, so shop around and see what you can find!
Where Do Alliums Grow?
For the most part, you will find alliums growing in the Northern Hemisphere. They do best in temperate areas. But some alliums also can be found growing in Brazil, Chile, and tropical regions of Africa.
When Do Alliums Bloom?
Depending on which cultivars you plant, alliums may bloom anywhere from May through July.
How Long Do Alliums Bloom?
Allium blossoms last for around three weeks.
When to Plant Alliums
If you want to enjoy alliums in your garden this coming spring, you need to make sure that you plant them in the fall. That means you will need to do some planning ahead.
While you can check your local garden center for allium bulbs, chances are good that you will not find much of anything. Usually, it is necessary to order alliums online.
The temperature of the soil should be around 55 degrees Fahrenheit when you plant your allium bulbs. If the weather at night is in the 40s, that is ideal.
Ideal Growing Conditions for Alliums
Now that you know when to plant alliums, let’s talk about the growing conditions in which allium blooms thrive.
How Much Sun Do Alliums Need?
Alliums can handle partial shade, but it is best if you can plant them in full sunlight. Their sturdy stems will be at their strongest if they are exposed to more sun, which means that they will stand neatly upright rather than drooping.
What Type of Soil is Right for Alliums?
The best soil for alliums is rich and well-drained. They should not be left in soggy ground or standing water. If they are, the bulbs will rot.
Beyond that, alliums are pretty flexible with respect to soil type.
How Much Water Do Alliums Need?
Allium plants are able to store their own water. That is why they are drought-resistant.
While you do have to water them right after you plant them, after that, they should not require much watering from you at all, if any.
If 3-5 days pass without rain during the bloom season, you can water your alliums.
Just remember, you do not want soggy soil. If you get your soil too wet, your allium bulbs will rot and you will lose your plants.
How to Plant Alliums
Eager to get started with growing ornamental alliums? Let’s talk about how to plant these beauties in perennial gardens.
To Plant Alliums in a Flower Bed …
1. Choose a site.
It should receive 6 hours of sunlight per day at a minimum. If it receives more, that is even better. Again, make sure it is not a spot where standing water is going to be an issue if it rains.
As for spacing, your alliums should be planted with 6 to 8 inches between them. If you plant them too close together, they may not grow as well since they will be competing for nutrients.
That being said, you also do not want to isolate your alliums, planting them really far apart. They look best if they are grown together in groups.
2. Start by preparing your soil.
If it has a sandy loam consistency, that is ideal. You can grow alliums in clay, but you will need to break it up and add sand, compost and/or peat moss to improve the consistency. Soil that is really sandy will require the same improvements. Ideally, the pH should be neutral.
3. Dig a hole and plant your bulb.
For each allium, you will need to dig a hole that is around 6-8 inches deep. The pointed end of the bulb should be pointing upward.
Do not fertilize inside the hole. If you do, you will cause root burn.
Now, cover the bulb with soil and pat it down. Make sure that the soil doesn’t dip downward over the bulb, and that there are no holes. Either of these could lead to water draining down onto your bulb and rotting it.
4. Water and fertilize.
You should water your allium after you plant it. As mentioned previously, you should not need to water much thereafter.
While it was important not to fertilize inside the planting hole, you can scatter some fertilizer on the soil when you are done.
To Plant Alliums in Containers …
1. Choose a pot and a location.
First, pick a pot. If you just have a regular large pot, it probably will only be able to fit one allium bulb, since they need to be planted 6-8 inches deep and be spaced 6-8 inches apart.
If you want to plant multiple alliums in a single container, you might consider a long trough planter.
Make sure there are holes in the bottom of your pot or trough so that the water can drain out. Fill it with appropriate soil (nothing that will turn to mud).
Look for a location in your garden for the pot. Choose a location that receives as much sunlight as possible. One of the nice things about planting alliums in containers is that you can be more selective about where you put them, giving you a chance to grow the most dramatic blossoms.
2. Plant the bulbs.
Follow the same basic directions to plant bulbs in planters as you do in your garden bed. Dig down 6-8 inches, and make sure the pointed ends are facing up. Then, cover them back up with soil and try to get the surface as even as you can. Check to make sure there are no holes in the soil.
3. Water and fertilize.
Next, water your plants, and if you want, fertilize them. Once again, do not fertilize inside the planting hole. Only put some fertilizer on top of the soil.
5. Consider bringing your alliums indoors for the winter.
Since you are growing your alliums in pots instead of directly in your garden beds, you do have the option of bringing them indoors for the winter.
You might want to do this if you are in zones 3 through 7 (especially the lower end of that range).
If you do, you should keep the planters in a cool, dry location.
If you cannot bring them indoors, that is probably not going to be a problem, at least not for zones 5-9.
To Grow Alliums from Seeds …
Usually, people grow alliums from bulbs. But it is also possible to start alliums from seeds. Below are the directions.
1. Get a tray and prepare it for the seeds.
You will need to start with a tray, preferably a deep one. It should also be wide.
Put potting soil in the tray which has been amended with compost.
Create furrows for the seeds. Each one should measure between a quarter and a half inch, and should be separated by 2 inches or so.
2. Put the seeds in.
Plant the seeds in the furrows. Every inch or so should contain about 6 seeds.
3. Wait for the seeds to germinate.
Although you do not want allium bulbs to get really wet, you do actually want to get allium seeds a bit wet as they are germinating. So, keep the soil moist.
But here’s the thing—you need to keep the air circulating as best you can. Doing so will help prevent mold from taking hold (though you will likely still have this happen with some of your seedlings).
4. Transplant the allium seedlings.
Calculate the date of the last expected frost for the year, and then subtract six weeks from that. It is around that time you should plant your allium seedlings. It will probably be in February.
Ideally, each seedling should be about the same thickness as a pencil by this point. Alas, that probably will not be the case. Hopefully, their diameters are at minimum an eighth of an inch.
Take the allium seedlings outside and plant them in your garden beds or containers, and wait for them to grow.
Be aware that this is the slow way to start ornamental alliums. In fact, do not expect flowers the first year. It will take several years before you see them.
How to Store Allium Bulbs
Have you received your allium bulbs in the mail? Unless it is time to immediately plant them, you will need to store them for a time.
You will need to keep your allium bulbs somewhere cool and dry. They should not be exposed to temperatures below 50 degrees Fahrenheit or above 70 degrees Fahrenheit. Keep them out of direct sunlight. Do not let them get wet, and do not freeze them.
How to Care for Alliums
Now that we have talked about storing and planting alliums, let’s talk a bit more about caring for these easy-to-grow bulbs and the stunning flowers they produce.
How to Fertilize Alliums
As we already mentioned, you should not put fertilizer in the hole with the bulb so as to avoid root burn. But you can scatter it on the surface of the soil.
What type of fertilizer should you go with? A granular organic formula is best. Consider either 5-10-5 or 4-10-6.
How to Mulch Alliums
Generally speaking, mulching alliums isn’t necessary in most areas. But if you live in a cold zone where alliums may or may not make it, it can be useful to mulch during fall and winter.
You should wait for the ground to freeze before you apply the mulch. Oak leaves, straw, and salt marsh hay are all worth considering. Around 2 inches should do it. You do not have to clear the mulch away when springtime rolls around, but you should at least loosen it.
How to Stake Alliums
Should you stake alliums? That depends on the conditions in which you are growing them. In general, most alliums will stand upright on their own thanks to their sturdy stems even if you do not stake them.
But there may be exceptions. If you are growing your allium flowers in partial shade, their stems may not be as strong as they would be if you were growing them in full sun. So, staking might be wise.
Also, if you are growing alliums in a location that gets a lot of strong wind, that is going to stress the stalks. So once again, it is a good idea to stake them.
Finally, if you are growing really tall alliums, staking them may be helpful. They might be able to stand upright on their own, but sometimes they need a bit of extra support.
Are Alliums Vulnerable to Diseases or Pests?
One nice thing about allium plants is that on the whole, they tend to be disease-free, and insects generally do not infest them.
That being said, if you put compost in your soil that is carrying a fungal disease, you can expect it to potentially infect your alliums. You can avoid this by only using fully decomposed compost.
How to Prune Alliums
You don’t really need to worry about pruning alliums unless you want to deadhead them. You also can cut them back after the blooming season is over.
How to Deadhead Alliums
You should deadhead allium flowers if you do not want the spent flowers to go to seed. You also might be able to extend their bloom period this way.
The right time to deadhead an allium is when most of its petals have fallen. You can just trim it off right below the base of the flower.
A lot of people do not do this at all, however. They simply cut back the alliums later and skip deadheading altogether.
Why? Because the allium seedheads are quite beautiful in and of themselves. Moreover, each seed head can collect frost in the winter, creating a new, dramatic display. So, for winter interest, consider leaving them be.
The main reason you would want to consider deadheading your alliums is if you are concerned about them self-propagating.
They can spread very quickly, and take over your garden if you do not take care.
When to Cut Back Alliums
You can cut back your allium plants as soon as they start to turn yellow (do not forget to mulch if necessary).
But again, you might want to consider leaving them in place as long as possible during the winter. But if harsh conditions start to damage the dead stalks, you can remove them after they have lost their aesthetic appeal.
How to Divide Allium Bulbs
Over time, allium bulbs will multiply in the ground to the point where you can and should divide them. You will need to take care of this chore every few years.
When it is time, use a trowel to dig gently around the allium. Be very careful not to damage the plant. After you have loosened up the soil, you should be able to pull the allium free. Where you originally had one bulb, now, you should have a few.
You are going to want to pull the allium bulbs apart so you can re-plant them separately. It should be easy to do this by hand.
After you have divided the allium bulbs, you should plant them again without delay. Follow the same basic instructions you did to plant them originally.
Recommended Companion Plants for Alliums
When it comes to companion planting, alliums will likely do more favors for other plants than they will do for alliums. The reason is that alliums are already resistant to most animals, insects, and diseases.
So, when choosing flowers to place with your alliums, the choice is largely an aesthetic one. Here are a few ideas you might consider:
Golden Marguerites: This type of flower looks similar to daisies, producing flowers with yellow petals and orange centers. They grow densely, forming a beautiful blanket of sunny brightness. If you grow alliums with them, the allium stalks can rise up above the Marguerites, and the purple shades of the alliums can contrast magnificently with the yellow. Moreover, butterflies like Marguerites, so you can attract some to fly among the bees enjoying your alliums. Additionally, this is yet another drought-resistant plant, so if you are in an arid location, you can expect Marguerites to thrive among your alliums.
Lupines: Pretty much any lupines will look breathtaking planted with alliums. The spikes of flowers feature magnificent colors and form dense geometric shapes that make an intriguing accompaniment next to the ball shapes of allium flowers. They grow well in full sunlight, just like alliums, and also require well-drained soil.
Calla lilies: The graceful, streamlined forms of calla lilies juxtaposed with the ball shapes of alliums makes for an elegant combination. As they like full sun or partial shade, they can be planted in the same locations as your alliums with no issues.
You can find many more ideas for companion plants for alliums if you do some research. But you really can't go wrong with anything you come up with on your own either.
Frequently Asked Questions About Growing Alliums
Q: How tall do alliums get?
A: There is quite a significant range in heights for alliums. Short cultivars of alliums grow to just 6-12 inches (or even less). These can make nice borders along paths. But if you want to grow taller alliums, there are some cultivars that can reach as high as 8 feet tall.
Q: What eats alliums?
A: Sometimes leaf miners might chow down on alliums, but on the whole, most animals and insects avoid these plants.
Q: Are alliums expensive?
A: the cost of purchase allium bulbs depends on the cultivars you are interested in. Some of them are quite inexpensive, while others are a bit pricier.
But you should keep in mind that allium bulbs multiply and can be divided every few years to produce additional plants. So, from that standpoint, even the more “expensive” alliums are actually quite reasonable.
Q: Are alliums toxic to dogs and cats?
A: Yes. James Watts, BSc Bioveterinary Science, explains, “The most recognised members of the Allium genus are onions, garlic, leeks, chives and shallots. Allium species contain organosulphur compounds which are toxic to cats and other animal species. As these plants are often used in cooking, be aware of waste left during meal preparation. Gastrointestinal distress, lethargy, excessive thirst and anaemia have been reported in cats.”
Alliums are equally unsafe for dogs.
So, if you have dogs or cats, make sure that you only plant ornamental onions or other alliums where they cannot reach them.
If you cannot keep your pets away from your alliums, you should grow something else that is pet-safe instead.
Q: What is best to plant with alliums?
A: As already mentioned, alliums themselves make excellent companion plants for anything you want to protect from deer or other animals since their odor can help keep unwanted dinner guests away.
That being said, alliums should not go too close to beans, peas, asparagus, turnips, and some other veggies. Why? Because they can interfere with their development.
But what about companion plants for alliums? A few options to consider include lupines, calla lilies, and Golden Marguerites.
Q: Are alliums annual or perennial?
A: The majority of alliums are perennial plants. That means you can look forward to them going back every year.
Where to Buy Alliums
If you have already checked your local garden center, you probably found few or no alliums in stock. So, where can you purchase alliums for your perennial garden?
The best place to purchase alliums is online. You can have the bulbs shipped to you in time for planting season in the fall. you will find a wide selection of cultivars, allowing you to choose the perfect varieties for your garden.
To get beautiful, easy-to-grow alliums for your garden now, click the link below.
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