The Iris (EYE-ris) genus contains between 260 and 300 species of stunning flowering plants. Also, there are countless cultivars available.
Chances are, you already know how to propagate irises through division.
But did you know they can also be grown from seed?
It’s not uncommon to have problems germinating an iris seed, which is one of the biggest reasons seeds are seldom used.
Yet, those who grow these plants from seed say the results are well worth the effort.
How To Grow Iris From Seed?
Although the methods vary quite a bit, there aren’t many steps involved in growing iris seeds.
Let’s look at the more straightforward methods, which tend to be as effective as the more complicated ones.
Beware Of Cultivar Seeds!
Without an important disclaimer about cultivars, no competent guide on seed propagation would be complete.
- These plants are cross-bred or even grafted from 2 or more parent plants.
- As a result, their seeds are most often of a specific parent.
- So, when using the seeds of a cultivar, you never know what you’ll be getting.
- This problem also happens to a lesser degree with variants.
- They have often reproduced enough to become somewhat stable.
The good news is that growing a species plant from seeds will almost always get you another plant of that species unless it cross-pollinates with another species.
Harvesting Seeds
Now that the boring disclaimer is over, we must warn about deadheading.
When you plan to harvest seeds from a particular iris plant, it’s crucial to avoid deadheading your iris. This prevents the seed pods from forming.
These pods tend to increase during the summer months and dry out and return brown when they’re ready to harvest.
Keep an eye on browning pods so you can harvest them before they split and spill their seeds.
A simple method includes these steps:
- Hold a paper bag under the ripe pods.
- Snip them off into the bag.
- You can then allow the pods to crack open naturally.
- Harvest the tiny brown seeds inside.
Iris seeds have a shelf life of several years when kept in a cool, dark place or used immediately.
Preparing The Seeds
This step is where things get the most confusing.
There are many techniques, from simply planting the seeds to freezing and boiling them.
But one of the best methods is to do the following:
- Soak the seeds in a bowl of room-temperature distilled water for 2 to 14 days.
- Be sure to change the water daily, using a strainer to catch the seeds.
Not only does this method reduce the risk of damaging seeds, but it also removes many hindering elements without the need for nicking.
Sowing
There are two different methods to consider.
Many irises need cold exposure to germinate.
Plant them directly into the ground around September, when the summer heat has subsided.
As the winter can strip away inhibiting factors, it’s not always necessary to soak these seeds before planting.
Plant irises that don’t need the cold to germinate (including crosses of reblooming irises) in a window box or bucket during the winter and outdoors later.
For these, here are the steps to follow:
- Use equal parts potting mix and either seed-soil or germinating mix.
- Top the container off with more of the germinating mix you chose.
- Sow your iris seeds approximately ¼” an inch deep and at least ½” an inch apart.
- Avoid planting more than 25 seeds in a single container.
- Place your containers under a grow lamp with temperatures kept between 60° and 70° degrees Fahrenheit.
It’s essential to keep the soil of potted seeds moist, as any dryness can reduce their viability.
Avoid flooding the container, and add a little water when the soil feels dry to the touch.
You may also find it helpful to cover the containers in clear plastic to help retain moisture.
A third option is to take treated seeds that don’t need cold exposure and sow them directly into the ground after the last frost has passed.
Germination
Cold-treated seeds won’t sprout until the spring, which may be anywhere from 4 to 12 weeks away.
Conversely, indoor potted seeds can take around 28 to 35 days to germinate but are a little more prone to decay without proper care.
Transplanting
When transplanting irises sown indoors, remember these steps:
- Choose some biodegradable pots and gently score the inside surfaces.
- When digging up and planting the seedlings, take care not to disturb their delicate rhizomes.
- Plant the pots with your seedlings spaced approximately 18” inches apart.
- For those sown outdoors in the winter, thin them out to this same distance.
Note that none of your new irises will bloom until their second spring.
A Final Surprise
Iris seeds have a long lifespan, germinating in the wild up to 18 years after being sown.
You will likely have 50% percent or more of your seeds germinate, but don’t count the rest out just yet!
Keep the containers they were sown in, or dump the soil in an unused garden space.
You might discover those very seeds sprouting the next year or even a few years later.
Perhaps one of the biggest joys of propagating through seeds is never knowing when a new plant will appear from a seed you thought wouldn’t grow.