How to Plant Iris Bulbs

Last Updated on September 23, 2022

Learn how to plant iris bulbs for a display that’s simply Iris-istible!

If you’re planning to grow some bulbous plants in your garden, plant Iris bulbs. These spectacular flowers are named after the goddess of rainbows and are among the most vibrant garden perennials in the world. If you live anywhere in USDA zones 3-9, these hardy perennials will perfectly flourish in your backyard.

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Do irises grow from bulbs or rhizomes?

All iris plants are perennial. They can grow from creeping rhizomes or from bulbs.

Bearded, beardless and crested irises grow from the rhizome.

Reticulata iris (blooms in spring ) and Dutch iris (blooms in summer) grow from bulbs.

When to plant iris bulbs

It is best to plant iris bulbs in the fall when the soil cools off and the temperature stays between 40 to 50 degrees Fahrenheit. Try to plant them before the first frost. If you miss that window, then wait until the ground thaws enough to plant them.

Take the temperature of your soil with the help of a soil thermometer and make sure that for the next 12 weeks it will stay below 60 degrees, or think about planting your irises in pots.

Timings of planting iris bulbs in USDA zone 3-9:

USDA Hardiness Zones 3 – 5: Plant in September

USDA Hardiness Zones 6 – 7: Plant in October

USDA Hardy Zones 8 – 9: Plant in December

Related reading about fall activities 😊:

Can you plant iris bulbs in the spring?

Yes, you can.

If iris plants are planted very late in winter or early spring, they may not bloom the first year, but they will still establish their root systems and bloom the coming year.

Where to plant iris bulbs

It’s best to grow irises under full sun to enjoy their display of blooms. They can also survive in half a day of sun, but it’s not ideal for them. When there is not enough light, they fail to bloom.
They like to grow in neutral to slightly acidic, well-fertile soil.
Proper drainage throughout the year is crucial. Irises can’t tolerate soggy soil in winters.

Should I soak Iris Bulbs Before Planting?

It is not a mandatory practice, but you can do it to shorten the growing time.

Soak fall-planted bulbs in warm water for 12 hours before planting. Soaking allows the bulb to absorb enough water to begin growth early, which helps save 2 to 3 weeks of time.

Before planting iris bulbs, soil preparation is important. You can either grow them in a container or directly in the ground. Here are a few things that you need to do.

Preparing the Planting Site

Iris bulbs require well-drained soil. Therefore it’s better to grow them in a raised flower bed.

Prepare the soil: mix the garden soil with compost and bulb food to make it fertile.

Check soil pH. Irises can tolerate neutral, slightly acidic or slightly alkaline soil.

Also, make sure that your picked site is getting enough sun for the flowers to bloom.

Planting irises in the ground

1. Make 4″ (10 cm) deep holes in the ground. Leave a space of 4″ between holes.

2. Place Dutch or Reticulata iris bulbs in holes, with their pointy ends facing up.

3. Fill the holes with the soil. Make sure that bulbs are staying upright.

4. Now perform a deep watering ritual. 😊 Watering at this stage will help bulbs in sprouting leaves quickly.

How to Plant Iris Bulbs in Pots

If you’re planning to plant iris bulbs in pots, buy 6″ (15 cm) deep pots with drainage holes or cute bulb pans that can be used indoors and outdoors.
Now get some high-quality potting mix to fill these pots.
If your potting soil is not the “ready to use right out of the bag” kind, then mix your potting medium with compost so your iris bulbs can get enough nutrition for their growth. Then fill the pot or container with this potting mix until it is ¾ full.
Put the bulbs on the soil’s surface to give them a little push so they can get inside the soil. This way, you can make sure that the bulbs will stay erect. Remember to keep the pointy ends of the bulbs facing up.
Top it off with another layer of soil.
After planting, water the soil until it is moist enough.
Now put your pot with irises in a sunny place and wait for the magic to happen.

Iris care

Caring for irises is pretty easy.

Bulbous irises require a moderate amount of watering. In summer and winter, keep the soil of your plant less moist or relatively dry.

Aside from proper watering, you also need to keep insects and pests away. A certain pest usually attacks when the irises reach their budding phase. If you want to keep your plants safe, use an organic insecticide to repel them.

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If you want to use irises as cut flowers, cut them before the buds open and blossom into mature flowers. This way they will look gorgeous and stay beautiful for a few weeks.

Do irises come back year after year?

After completing the flowering period, bulbous irises die down. Then, they remain dormant throughout the winters.

You don’t need to do anything at this stage. Leave them in the ground, and they will sprout and bloom again after the winter is over. However, you must transplant the bulbs once they reach the age of 4.

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Final thoughts on planting iris bulbs

Whether as cut flowers or beautifying a border, bed, or container, you’ll love the vibrant color that irises bring to your front or backyard. These are among the most elegant, glowing, and colorful hardy perennials that you can grow from bulbs. With only basic knowledge, you can grace your garden with ever-multiplying, long-lasting blooms of irises for years to come.