Bunch of irises with blue and white colors

The Complete Guide on How to Plant Irises

Irises are admired all around the world for their beauty. That’s why many gardeners choose to have them in their own backyards. They are hardy flowers and can grow well in a variety of climates. Moreover, they don’t require much maintenance, which is why they are preferred. Today we will have a look at how to grow irises and how to take care of these beautiful plants.

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Before Planting

1. Choose the Right Variety

Almost all varieties of irises are hardy and easy to grow. However, some are more suitable to certain conditions than others. Here you have a couple of varieties, the most common ones, and where they grow best:

  • Beardless Iris – Grows in Central and Southern Europe. They require half a day of full sun and can bear constant sun if needed.
  • Siberian Iris – Surprisingly, it doesn’t grow in Siberia, but in Turkey, Central and Eastern Europe. It is very adaptable so it doesn’t require much work for growing and maintaining. Suitable for temperate climates.
  • Louisiana Iris – This variety belongs to humid and hot areas, like the ones in the SE of the U.S. Despite this, it can adapt to lots of conditions. During the hot growing season period, it requires at least an inch of water. Less water means that they aren’t going to bloom well.

2. When to Plant

Besides knowing how to plant irises, you also need to know when to do it. The best time to plant irises is in late summer. Most irises do well if they are planted in early fall the latest. In this way, they can get enough sunlight to grow, but also enough time to set their roots so that it can survive over winter. However, if you live in an area where summers are long and winters are mild, you should know that you can plant even as late as September or October. This happens because the plants will still get enough sunlight to grow before winter comes.

3. Choose a Good Location

The ideal location offers 6-8 hours of full sun each day for the irises. Most of them love having as much sun as possible, so keep that in mind. Ideally, they should stay in a flowerbed that gets shade from a tree in the late afternoon. Alternatively, place them on one side of the house where the sun hits during the afternoon so that they can get even more light.

4. Prepare the Soil

You should always use a soil tester before getting down to learning how to plant irises or any other flowers. Irises love soils with a pH of 6.8 – 7.0, so it must be neutral to acidic. Moreover, soil aeration is particularly important for them, as well as drainage. These two factors prevent the roots from rotting, which can happen if you over-water the plants.

If you have a soil that is heavy and rich in clay, try improving the drainage by adding organic matter or humus. This helps make it more permeable. It’s a good idea to plant in a raised flower bed or on a slope. In this case, water will naturally flow away from the plant.

How to Plant Irises

5. Planting Position

One of the most common mistakes people make when learning how to plant irises for the first time is to plant them too deep. As opposed to most plants, irises thrive when the rhizome has a slight contact with air. The rhizome is the brown structure that looks like a root, placed at the base. As such, the plant’s roots should be spread out downward, just beneath the rhizome. If you live in a very hot climate, it’s a good idea to cover up the rhizomes with some dirt in a thin layer (around an inch). This helps the irises not dry out.

6. Space Them Correctly

If you don’t know how to plant irises correctly, you might end up having a whole bunch of underdeveloped plants. When you plant them next to each other, they tend to grow together. In this case, they will start competing for the resources: water, nutrients, and soil. This means that they will hamper their growth themselves. For this reason, they should be planted 1-2 feet apart. After a couple of years, they may still tend to grow together, case in which you should replant them farther from each other.

7. Growing Conditions

An important decision you should make when thinking about how to plant irises is where to do it. Sometimes, the conditions outdoors may not be the best for a growing iris. Instead of planting it outside, where the soil, the weather conditions or the time of the year may be unfavorable, choose a pot instead. Thus, you can control the amount of light, water or warmth they need. Eventually, you can transfer them outside in your backyard. If not, you can keep them forever in a pot.

Most varieties require a 12-inch pot. If you choose to grow a smaller variety, then you can do perfectly with 6-8 inches one as well. In any case, you need to ensure a good drainage. Make one big hole on the bottom or various smaller ones to let water out of the soil.

Caring for Irises per Season

8. Water them Generously

Immediately after planting, you need to water them seriously. If you have dry conditions for the plant, you should water it every 7-10 days. If it needs more water, do it as often as necessary in the morning or evening. In case you planted them at the beginning of the fall or the end of the summer, the watering process should stop when the weather cools and it rains or snows.

When learning how to plant irises, it’s extremely important not to over-water them. There is a high risk for the roots to rot if you don’t let them drain. Eventually, the root rot can kill the iris and even spread to other nearby plants, so make sure you prevent this.

9. In Time, Water Less

Over time, irises require less and less water. When the weather turns cool in the fall, you don’t need to water anymore until the next growing season in summer. However, if you live in an area with dry and hot summers, you may still need to water the plant every summer so it doesn’t dry out. Even though they are hardy and durable varieties, they still need some help in extreme conditions.

10. Take Care of Rhizomes and Roots

In general, you need to periodically check the rhizome and the roots. Make sure that the rhizome isn’t covered with debris, dirt or other types of organic matter. If you do notice this happening, brush it off delicately. Don’t move the plant or disturb the roots. Check if the soil is still well drained and aerated.

11. Trim the Brown or Dying Leaves

Generally, you don’t need to trim the irises or prune them to grow well. It is recommended to leave the leaves undisturbed since they turn into nutrients for the next year. The only trimming irises need is the one for the dead leaf tissue.

Pests and Possible Diseases

12. Weeding and Protecting against Pests in Spring

When the weather starts warming, you can let the snow melt on its own if you planted the iris in the garden. When new plants sprout up, watch out for any weeds that might invade your flowers. Pull them out as soon as you notice them. In general, it’s good to use some environmentally-friendly herbicides and weed killers. This keeps grasses and other types of weeds away from the irises’ roots.

There may also be some other encroaching pests, such as slugs. Luckily, there are plenty of options for baiting slugs, from home-made solutions to commercial ones. A beer trap is one of the most common ideas: take a jar with a wide mouth and fill it halfway with beer. Bury it up to the rim and slugs will fall inside.

13. Using Fertilizer

If you want to know how to plant irises the right way, you need to know how often to use fertilizer. Ideally, you should apply lightly some fertilizer every now and then. Start with the growing season after you planted it. Don’t go for a fertilizer that has high amounts of nitrogen. This may make the foliage grow excessively and even rot. After you place the fertilizer, water the plant so that it doesn’t “burn”.

Among the fertilizer you can use, you will find general purpose “5-10-10” or “5-10-5” ones, bone meal or superphosphate.

Here you have a brief clip that demonstrates the entire process:

Conclusion

As you have seen, it’s not complicated to learn how to grow irises in a pot or in your own backyard. They don’t require much maintenance and you need to tend to them less and less as they grow. You need to pay some attention to the rhizomes and roots though since there’s a risk for them to rot. Other than that, most of the time you need to leave them alone to grow. Even so, it’s a good idea to check on them constantly and see if there is any problem. In this way, you can prevent the appearance of pests or diseases.

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Bonnie Enos

I spend my time in my garden trying to create the greatest outdoor space possible. My garden is my happy place and where you will always find me on a nice day. I take my experience and share it here for you to read!

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