Plant These Giant Purple Flowers This October for a Garden Full of Color Next Year
Purple flower globes rise above coneflowers and grasses on tall stems, some reaching several feet from the ground. By the time they appear, the most important part of the job happened months before. These are ornamental alliums, and if you want them in your garden next year, fall is the time to put their bulbs in the ground.
Why October is a good time to plant alliums
Ornamental alliums grow from bulbs that benefit from a cold period before spring growth. In regions with cold winters, October often falls within the planting window: temperatures have dropped, but the ground has not frozen.
Don’t rely on the calendar alone. Wait for cooler fall conditions and plant before the soil becomes too hard to dig. In warm climates, planting may need to wait until later in fall.
Set each bulb with the pointed end facing up. Planting depth depends on bulb size, but a common guide is around three times the bulb’s height. Large allium bulbs need more depth than small varieties.
The spot matters more than fertilizer
Full sun and draining soil give alliums what they need. Bulbs can handle winter underground, but soil that stays wet raises the risk of rot.
That makes raised beds, slopes, borders, and other spots where water doesn’t collect good choices. Skip low areas that remain wet after rain.
Alliums also don’t need their own bed. Their bulbs take up little room, so they can sit between established perennials and send flower stems through the surrounding foliage months later.
Plant several bulbs for the purple-globe effect
One allium creates a purple accent. A group creates the display seen in these gardens.
Instead of spacing bulbs in a rigid row, plant them in clusters or loose groups among coneflowers, grasses, salvia, catmint, or other perennials. Check the variety before planting because allium heights vary. Some remain close to the ground, while giant types send flower heads several feet high.
The surrounding plants solve another problem. Allium leaves can start turning yellow while the flower heads still look good. Coneflowers and grasses cover the fading foliage while leaving the tall purple globes exposed.
Those giant globes are hundreds of small flowers
What looks like one purple ball is a cluster of many star-shaped flowers. Bees and other pollinators can visit those blooms, giving alliums a role beyond adding height and color.
Many ornamental alliums are perennial and can return after their first flowering season when the variety suits the climate and growing conditions. Leave the foliage in place until it yellows so the bulb can store energy before dormancy.
Planting a brown bulb in October isn’t much to look at. That’s the trade: a few minutes with a trowel now for purple globes rising above the garden next growing season.
Would you mix alliums through an existing flower bed or plant a large group together? Are you planting other?