Arisaema Planting & Growing Guide

Arisaema, also known as Cobra Lilies, are spectacular plants that rise from woodland floors with unusual blooms and wing-like leaves spread high above. Blooming late spring to early summer, the fantastical flowers flare like the hood of the serpent for which they're named. Arisaema thrive in well-drained, nutrient-rich soil with dappled sunshine overhead.

Whether you're planting just a few to make a striking architectural statement or are planning an extensive grouping, you can rest assured that these winged cobras will become a breathtaking focal point in your garden. If you're ready to complete your own corner of Eden, our planting guide will show you the way!

  • Planting Depth
  • Planting Proximity
    12-18" Apart
  • Planting Season
  • Plant Benefits
    Does well and provides garden interest in shade areas.
  • Water Quantity
    Moderate to Low
  • Bloom Season
    Late Spring to mid-Summer
  • Sunlight Quantity
    Bright Indirect
  • Hardiness Zones
    Species Dependent; Zones 6/7-10

Where to Plant

Cool, dappled shade under a spreading canopy of trees is an ideal growing habitat for Arisaema. However, the north or east side of a building that protects them from all day sun and heat will work as well.

When to Plant

Arisaema tubers are best planted in the spring, although you can also plant them in the fall. When grown within their hardiness zones, these unusual bloomers can remain in the ground, undisturbed over the winter, when given protection from rainfall.

How to Plant

  • Find a location with well-drained soil where your Arisaema will receive cool, dappled shade.
  • Work the soil well to break up any compacted areas and incorporate leaf mold, compost, and perlite to enhance the nutrition and structure.
  • Plant Arisaema tubers 4–6" deep, giving them a good chance to develop a healthy network of roots and protection from cold weather.
  • Water lightly after planting to settle the soil around the tubers.

How to Grow

  • Keep your Arisaema lightly moist through the growing season, but not wet. Water in the evenings with a sprinkler or watering can when the soil feels dry.
  • Apply a time-release granular fertilizer to the topsoil every spring and a water-soluble fertilizer or seaweed extract periodically during active growth.
  • Use a thick mulch of compost, leaf mold, dried grass clippings, or dead leaves to provide insulation for Arisaema left outdoors in the winter.
  • Withhold watering as your Arisaema slips into dormancy and keep them dry during the winter months.
  • Dig up the tubers if you live in a colder climate and store as if planting in pots, using a rich, soilless mix. Place in a cool, dark location that's open to air circulation and lightly dampen the soil every month until you're ready to replant the following spring.

Arisaema Tips & Tricks

  • Work the soil well before planting to break up any compacted areas, as Arisaema prefer porous soil with plenty of air spaces.
  • Overplant your Cobra Lilies with Achimenes tubers as a gauge for watering. When the Achimenes wilt, it's time to water your Arisaema, and when the Achimenes are happy, your Arisaema will be too!
  • Protect tender new growth from hard frosts.
  • Ensure your Arisaema receives excellent drainage, as the tubers and roots are prone to rot in poorly drained conditions. While fussy about their drainage, they will grow equally well in acidic or alkaline soils.
  • Plant in raised beds or small hillocks to help achieve the appropriate level of drainage.