Alliums do look stunning in a flower border, and the deeper the border is the better they will actually look. You can plant Alliums in thin borders as well, but you should definitely use smaller companion plants, as Alliums will provide vertical interest but their leaves are not the best looking ones. A flower border doesn’t need to be large, smaller borders are easier to manage, and most of them will benefit from a couple of Alliums.
To plant Alliums in a border make sure that the flower border is in a full sun location. Plant the Allium bulbs at the back of the border, as they tend to be rather tall, and avoid planting vining plants next to them. You can plant Allium bulbs alone or in clumps, although clumps of the same variety of Alliums do look a lot better than mixed clumps. Alliums will oftentimes self seed in the flower border, and if you allow them to do so you will see rivers of Alliums in the border after a couple of years.
One of the most beautiful Alliums in a flower border is the Giant Allium Globemasters, my personal recommendation is to grow them from seed, this way you can fill the flower border with them Click here to check it out on Amazon.com
Smaller borders can be overtaken by Alliums if they are the tallest plants, although it is relatively easy to thin them out. There are a lot of Alliums that bloom in different months, so with some careful planning, you can actually have different types of Alliums flowering one after the other.
You can also fill the border with just one type of Allium like Purple Sensation, Globemaster, Gladiator, or Mount Everest. If this is the first time planting Alliums and you don’t know which ones will grow well in your garden then I highly recommend getting a couple of bulbs from different varieties and see which ones grow the best in your flower border. If you wonder how late can you plant Alliums then check out my recent article How Late Can You Plant Allium Bulbs ( Winter-Spring ).
How To Plant Alliums In A Border
To plant alliums in a border, choose a location that receives full sun to partial shade and has well-draining soil. Dig a hole that is two to three times the depth of the bulb and place the bulb with the pointed end facing upwards. Space the bulbs according to the specific variety, typically around 6 to 8 inches apart. Once the bulbs are in place, backfill the hole with soil, firming it gently around the bulbs. Water the newly planted alliums thoroughly to settle the soil. Keep the soil moist but not overly wet during the growing season. Alliums typically bloom in late spring or early summer, and their unique spherical flowerheads will add a stunning focal point to your border.
Plant Them In A Full Sun Location
Before jumping in headfirst and buying a lot of Allium bulbs, you have to really consider if your flower border is actually good for them. Flower borders with partial shade are not good for Alliums, they will grow but they are less likely to flower. In addition to this, you should look at how crowded your flower border is, Alliums tend to grow relatively slowly and they can get outcompeted by other plants, especially by weeds. If you want to grow Alliums in pots then check out my recent article Grow Alliums In Pots ( In 6 Easy Steps ).
Plant Them At The Back Of The Flower Border
Alliums tend to be relatively tall, so if you do not grow any taller plants than the Alliums, then you have to plant them at the back. This way you are less likely to notice their leaves, but you will easily see their flowers. If you have relatively tall plants, taller or the same size as Alliums then you should plant them in the midsection of the flower border. It is extremely important to allow the Alliums to get full sun for at least a couple of hours every day for optimal growth.
Do not plant next to vining plants as they can easily choke the entire Allium plant. Try to avoid planting them next to roses that have thorns as they could damage the leaves of the Alliums.
Plant The Alliums 3x Times Deeper Than Their Height
Alliums grow the best if they are planted at the correct depth, if they are planted in a shallow hole then they will struggle. Ideally, you should measure the height of the Allium bulbs and plant them 3x times deeper. Make sure that you have a well draining soil, or amend it if you have relatively hard clay soil. I do grow my Alliums in clay soil, which is on a slight incline, so water tends to drain relatively well.
Make sure that there are no other flower bulbs right next to the Alliums, especially established flower bulbs as these will suck up all the nutrients from the area and the growth of the Alliums will be stunted. If you want to grow Alliums indoors then check out my recent article How To Grow Alliums Indoors ( In 7 Easy Steps ).
Use Clumps Of Alliums
Although Alliums do look good on their own as well, but if you clump them together they will look even better. Ideally, you should clump together the same types of Alliums, if you clump together different types of Alliums then they will not look that good, especially if they tend to flower at different times. The clumps of Alliums can be small to large, anything between 3-15 should look good, although it also depends on the size and the types of Alliums you grow.
If you have several different types of Alliums, but only a few bulbs then you might want to plant them alone, especially if this is the first time you are planting Alliums.
Let The Allium Leaves Decay Naturally
It is extremely important that you let the Allium leaves decay naturally after they have finished flowering. If you cut down the leaves too early you will stunt the growth of the plant, which in turn will either not be able to flower the next year or the flowers will be rather small. Once the Allium leaves have turned brown you can cut them off, this way you allow the plant to complete its natural life cycle.
Alliums Will Self Seed If You Let Them
Alliums tend to be relatively good self seeders, while this is a big bonus for some, it can get really out of hand in certain flower borders. The easiest way to stop them self seeding is to simply remove the seed heads or cut off the spent flowers. On the other hand, you can always harvest the seeds and plant them where you want, small seeds will turn into Allium bulbs in a year or two. If you let the Alliums self seed wildly in your garden you can easily remove the ones that you do not like.
Divide The Allium Clumps In The Broder Once Every 2-3 Years
If you have been growing Alliums in your flower border for a couple of years already and you notice that they are producing fewer flowers every year then this is a clear sign that the bulbs need to be divided. To divide the Allium bulbs simply dig them up in the autumn and separate the bulbs with a spade or with your hands. Make sure to only keep the biggest and the healthiest-looking bulbs, after which you can simply replant them.
Cover The Alliums With A Thin Layer Of Mulch In The Autumn
Once most of your flower border has died back in the autumn you should really consider mulching it. Mulches are extremely beneficial for all plants, but some might not be able to get through a thick layer of mulch, like Alliums for example. Make sure to use only a thin layer of mulch in the areas where you have planted your Alliums, in the spring you should check if the mulch has decayed correctly.
In certain situations mulches can get compacted, if the mulch is compacted on top of the Alliums then it is less likely that they will come up. At this point, you can simply remove the mulch and the Alliums should have no problem coming up.
Key Takeaways
- Plant the alliums in a full sun location, preferably in the mid or back section of the garden. Make sure to plant them 3x times deeper than the height of the bulbs, and use plant them in clumps.
- Alliums tend to self seed fairly well, to stop them you can deadhead the spent flowers, or simply collect the seeds.
- Make sure to divide the Alliums clumps once every 2-3 years as they will not grow that well if they are overcrowded.
