Growing allium from seed is a great way to increase your stock of these ornamental flowers. Not all alliums produce seed, however there are many cultivars that do. Learn how to grow allium from seed and fill your garden with beautiful ornamental blooms.
Ornamental alliums are a group of flowering plants known for their striking spherical blooms that add elegance and structure to gardens.
They belong to the onion family (Amaryllidaceae) and are prized for their unique flower heads, which are made up of numerous small florets arranged in a globe-like cluster.
The cultivars range in size from the smaller "drumstick alliums", Allium sphaerocephalon, to the larger giant alliums, such as Allium giganteum.
Alliums bloom in late spring to early summer, providing continuity in garden color after spring bulbs fade.
Most gardeners grow alliums from bulbs, which are planted in fall and bloom the following season.
However growing from seed is also an option. It's an easy and cost effective way to increase the number of allium plants in your garden.
Ornamental allium seeds can be collected from the seed heads, which form after the flowers have bloomed. The seeds can be grown by sowing indoors, direct sowing, or winter sowing. It will take several years for the resulting seedlings to bloom, and the resulting plants may look different than the parent plants in size and color.
Not All Allium Cultivars Produce Seed
Not all ornamental allium plants will produce seeds, and some varieties will produce only a few.
Some Alliums are sterile and will not produce any seeds. This is the case with varieties such as Allium "Globe Master", and Allium "Mount Everest."
Other cultivars produce seeds quite prolifically, such as Allium "Purple Sensation", and Allium christophii, or Star of Persia.
From seed producing alliums, the seeds can be saved and then planted, producing more allium seedlings for the garden.
Growing Allium From Seed
Allium seeds are black in color, and round in shape. The seeds have a rough textured surface, with many little puckers and dents.
To the naked eye, these seeds remind me of the actual allium blooms, as they resemble the flowers.
Seed size can be varied, depending on allium type or cultivar.
Purple Sensation seeds measure approximately 2 to 3 mm in length.
It will take alliums several years to grow from seed to bloom.
Plant your allium seeds at the same time that you plant your other seeds, whether planting indoors, direct seeding into the garden, or winter sowing into milk jugs.
Stratifying The Seeds
Allium seeds, like other perennial and hardy annual seeds, will benefit from a cold period, or cold stratification.
Stratifying allium seeds will help break dormancy of the seeds and improve germination rates. It also helps to break down the hard outer seed coat.
This process is naturally accomplished by planting the seeds directly into the garden.
The natural elements will help to break down the seed's coat during the long exposure to chilly temperatures throughout the winter months. As the seed is exposed to moisture, freezing, and thaws, it becomes naturally stratified.
Winter sowing in milk jugs will also have the same effect.
If planting indoors, stratify the seeds prior to planting by placing in a plastic bag in the fridge, along with a moist medium. Keep in the fridge for at least thirty days.
The medium can be moist peat, vermiculite, or even moist paper towel. The moisture plus the cold temperature is very effective for stratifying the seeds.
We are in zone 5b, with a temperate climate and snowy winter. Our alliums self seed, right in the garden space, and are stratified through the winter months.
They have been growing in the same spot for ten years now, with many new hybrid plants grown from seed.
Starting The Seeds Indoors
- Stratify seeds prior to planting, as previously discussed.
- Allium seeds can be planted in cell trays, or alternatively in open trays filled with a soilless medium.
- Fill cell trays or open trays full of soilless medium.
- Place one or two seeds in each cell. If planting in an open tray, sprinkle the seeds on the surface of the soil.
- The seeds require darkness for germination, so make sure to cover them.
- Cover with more of the same medium. You can also use vermiculite.
- Bottom water the cell tray. Mist the open tray. Keep moist while the seeds are germinating.
- Place on heat mat until germination occurs.
- When sixty percent of seeds have germinated, transfer to a shelf with grow lights.
- Grow under lights until ready to be transplanted out into the garden, after the risk of frost has passed.
- Make sure to harden off seedlings before transplanting.
Direct Seeding Into The Garden
- Direct seeding is one of the easiest ways to grow allium from seed.
- The time to direct seed can be in early fall or very early spring.
- In a prepared garden bed, or even at the base of the parent allium plants, sprinkle the allium seeds.
- Cover gently with some mulch or garden soil, as the seeds will require darkness for gemination.
- Water in gently with a fine mist hose, or alternatively you can just leave the seeds to allow the natural elements and rain to take care of the moisture.
- Seedlings should never be allowed to dry out during the germination process.
- The natural elements usually take care of this moisture provision in the outdoor environment.
Winter Sowing Allium Seeds
- Winter sowing is an easy and almost hands off method to grow any perennial or hardy annual seeds, including allium seed.
- It provides natural stratification in the outside environment.
- To winter sow, take a recycled milk jug or juice container and rinse well.
- Cut the container in half, leaving only a slight piece of plastic still attached, to allow the container to flap open.
- Poke drainage holes in the bottom half of the container.
- Fill the bottom half of the container with soilless medium.
- Sprinkle the seeds on the medium, then cover with a thin layer of medium or vermiculite.
- Label the container in several places, both inside and out with a permanent marker. The labels can wash off by accident when the jugs are outside, so it's a good idea to have them in several places.
- Place the top back on the jug, and tape the jug together with duct tape.
- Leave the lid off the container to allow moisture such as rainwater and snow to enter.
- Place the jug outside in a protected but uncovered area, to allow access to moisture.
- The seeds will germinate at just the right time for your growing area and climate.
Transplanting And Care
Once your allium seedlings are large enough to be transplanted, and have been hardened off, they are ready to plant into the garden. Unless of course the seeds have been directly sown.
Light Requirements
- Choose a sunny spot in which to plant the small allium plants, although you can also choose a partial shade location.
- You will have best flowering though in a full sun location.
Moisture Requirements
- Water in after planting. Keep the soil moist while the seedlings are establishing in the ground.
- Once the plants begin to grow, and the bulbs form, the alliums become quite drought tolerant, due to the storage nature of the bulb.
Soil Preference
- A rich soil is preferred, and good drainage is important.
- Avoid planting in areas with waterlogged or soggy soil, as this can lead to bulb rot.
Transplanting
- Transplant into the garden once hardened off.
- Space the seedlings 4–6 inches apart for smaller alliums, or 8–12 inches apart for larger varieties.
- Allow adequate spacing for airflow and future growth.
- Place seedlings at the same depth they were growing in the seed tray or pot.
- Water in well after transplanting, to settle the soil and reduce transplant shock.
Mulching
- Apply a thin layer of mulch around the seedlings to retain moisture and suppress weeds.
Saving Allium Seeds
If you are planning to grow ornamental alliums from seed, you may want to save some seeds from the garden.
The key is to allow the seeds to mature on the plant, and then harvest them when dried.
The Formation Of The Seed Pods
Alliums bloom in late spring to early summer. Our Purple Sensation allium blooms arrive at the same time as the tulips.
The head of the flower on each allium is made up of many tiny star shaped flowers which, if fertilized, will form numerous small seed pods on the spent flower head.
After the flowers are finished blooming the foliage dies back, and the seed heads begin to dry.
The dried flower heads, with sprays of seed pods, add a whole new structural look to the allium plants in the garden.
Even in their dried state, they are very interesting, and many gardeners leave them in the garden even at this stage because they are so unique.
If you plan to collect allium seeds, these seed heads can be harvested much earlier than many other types of seeds in the garden, which are often harvested in fall.
Wait for the seed pods on the seed head to become brown and dry before harvesting the ripe seeds.
In our garden, Allium seed heads are dry and ready for harvesting in mid to late summer.
If not harvested, the seeds themselves will naturally disperse, falling into the garden as the seed pods open, releasing the seeds.
Supplies Needed To Harvest:
- Large paper bag, or a large container
- Pair of scissors or snippers
- Label with tape and marker (if harvesting more than one type of Allium)
Collecting The Seeds
- There are several options for collecting allium seeds.
- You can harvest the entire seed head along with the seeds, or alternatively tap the seeds into your bag or container, allowing the seed heads to remain in the garden.
- Collect on a dry day when the seed heads are not moist from rain or heavy dew.
- Hold the bag or container under the allium seed head while cutting, as seeds can be very loose and easily drop into the garden.
- Snip under the seed head and gently place into the bag or container.
- You will notice many seeds will likely fall into your container during this process.
- Label the container if necessary, especially if you are harvesting more than one seed type.
- If using a paper bag to collect the seed heads, mark on the bag with a marker the seed type and date harvested.
- Store seeds in a cool place until ready to be stratified.
Frequently Asked Questions
1. Is it worth growing alliums from seed?
If you want to increase your allium stock, it is definitely worth it to grow alliums from seed.
Keep in mind, some allium bulbs can be very expensive, especially the larger varieties.
So if you have a larger cultivar which produces seed, and you want to increase your allium stock, you will be saving in the long run by collecting some seed.
It's important to know however, that hybrids will not be true to the parent plant, and that there may be variations in size, form and color in the new seedlings.
2. How long does it take to grow allium from seed?
Some allium seeds can germinate fairly quickly. Others may take up to three months to grow.
According to the Royal Horticultural Society UK, it may take up to 12 weeks for some allium seeds to germinate. See their growing guide with tips on propagation here.
If seeds are not germinating, all is not lost. You can place the container of seeds and soil into the fridge to further stratify the seeds.
We have an old seed fridge that we use for these purposes.
3. How long do allium seeds take to flower?
Ornamental alliums generally will take several years to grow from seed to bloom.
In the first year the tiny plant will grow, establish, and develop, saving energy for the next year's bloom.
This time frame is typical of many perennial flowering plants.
In year two you should see some blooms, and be rewarded with the results of your efforts. Some plants may take 3 years to bloom.
In Summary
Growing ornamental alliums from seed is a rewarding experience that combines patience with the joy of watching these stunning plants develop from tiny seeds.
Ornamental alliums are beautiful plants for the flower garden, and a great choice for spectacular spring blooms.
They can fill the garden with striking and interesting flowers, and attract lots of pollinators to the garden as well.
Growing alliums from seed is a great way to increase the allium plantings in your garden space. While it may take a couple of years for the first blooms to appear, the wait is well worth it
It's great fun to grow the seeds, and to discover the resulting new plants that may be different from the parent plants in shading, size and color.
Start your allium-growing adventure today and enjoy the satisfaction of growing these stunning blooms from seed to maturity!
We will certainly be planting and growing lots of allium seedlings in our garden this growing season.
Have you ever grown alliums from seed? Be sure to leave a comment below to share your experience!
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