Irises spread through rhizomes in the ground. Over time, they form more and more offshoots, but they also become lazy about flowering. Therefore, you should rejuvenate them regularly. Our guide will show you how to do this.
In a nutshell
- Irises shed with age and become lazy
- however, forms numerous lateral offshoots
- Dig up rhizomes every four to five years
- Rejuvenation by division into several sections
- Always plant the sections in a new location
reasons
Provided they are in the right location, irises are floriferous and uncomplicated plants that even multiply all by themselves over time. However, if you take a closer look at older stocks, you might notice the flowers getting smaller every year. It can also happen that only the outer rhizomes produce flowering shoots and the inner ones remain bare. The reason for this laziness in flowering in the iris is neither a lack of nutrients nor a wrong location, but simply a lack of space. By dividing the rhizomes and planting them individually, you give the sections the necessary space for growth, with the result that you can look forward to beautiful flowers again the following year.
time
Depending on the species and variety, irises bloom at different times. What they all have in common, however, is that the best time to divide is after flowering - provided it is not too hot and dry at the same time. In this case, it is best to wait a little longer and wait for milder weather. In principle, you can also rejuvenate and transplant the rhizomes in September. It is only important that the offshoots can take root in the new location in time before winter.
In order for your irises to keep blooming so beautifully, you have to keep dividing them.
Tip: Ideally, you should divide regularly every four to five years to prevent the lilies from aging.
manual
With our detailed guide, you can easily divide and rejuvenate your irises.
prepare ground
Before you start digging up the iris rhizomes, you should first prepare the new location. Proceed as follows:
- dig up the ground
- loosen the soil
- crush coarse chunks of earth
- Add mature compost, about one scoop per square meter
- additionally improve loamy soil with sand or gravel
- Rake the bed smooth
Tip: The best way to use the old space is to plant other types of plants, such as perennials. In this way, the floor can recover and does not tire due to one-sided loading.
Raise irises
The rhizomes grow just below the surface of the soil and are often not even covered by soil. However, it is difficult to estimate where the strands actually run. Therefore, you should not prick out the iris with a spade, as is sometimes done with perennials. You could injure the rhizomes, which is why they can no longer be planted afterwards. It is best to carefully dig out the plants with a digging fork, paying attention to the leaves and leaf bases: these must not break off. The rhizomes should not break off or tear.
You have to carefully dig out the rhizomes of the iris.
share plants
Now, if possible, bring the lifted plants to the new location so that you can plant them immediately after dividing without any major delay. Don't leave them there for a while or the chances of growth will decrease. Divide the rhizomes as follows:
- Cut off hand-sized pieces with a sharp knife
- a sharp spade is also suitable for this
- Keep cutting surfaces as small and straight as possible
- Dust cut surfaces with charcoal powder if necessary
- one healthy, well-developed tuft of leaves per section
- remove dried and diseased plant parts
Notice: You can confidently sort out the oldest rhizome parts, especially since the plants develop new lateral rhizomes and thus new, younger offshoots every year.
Cut roots & leaves
Now shorten the roots by about a third of the original length with a pair of sharp pruning shears. The leaves also need pruning: trim them back to about four to six inches. These measures help the plants to grow more easily at the new location and have fewer problems such as a lack of water supply to contend with. The large leaves contribute significantly to the evaporation of moisture, which now has to remain in the roots for rooting. In addition, the sections cut in this way do not tip over so quickly after planting.
Notice: Make sure that all cutting tools are always well sharpened and above all clean. It is best to disinfect them thoroughly before cutting, e.g. B. with a disinfectant from the garden store. So germs don't stand a chance.
Plant sections
Finally, plant the irises in the ground at the new, prepared location. The sections should be placed so flat in the ground that the top of the rhizome is still visible. Now water the plants carefully and thoroughly with a shower. In the coming weeks, the newly planted bed should always be kept slightly moist, as this helps with rooting.
Divided irises quickly begin to sprout again and soon bloom in full bloom again.
frequently asked Questions
Can all Iris species be divided in the way described?You can divide and rejuvenate not only the bearded iris, but also all other types of irises in the manner described. The only exception is the reticulated iris (I. reticulata), since this is the only species that does not grow from a rhizome. Instead, it is a bulbous plant, but it also develops daughter bulbs. These can be separated for propagation and planted in a new location.
Can you transplant irises in spring?We would like to advise you against this for two reasons. On the one hand, after transplanting in spring, you will almost certainly have to do without the iris bloom for this year, as the plants put all their energy into growing. On the other hand, irises are in their fullest power in spring, from which you tear them out with one action. Some varieties are very sensitive to this and with a bit of bad luck they would still hold it against you in the coming year. Others (e.g. 'Indian Chief') are considered to be very robust and would even survive transplanting at the wrong time.
How deep do I have to plant the iris?The iris is a very flat plant, the rhizomes of which remain very close to the surface of the earth and are sometimes not even covered. It is best to plant them so that about a third of the strands remain above the ground and the rest are only just covered with soil. The same applies when you plant onion species. The optimal planting distance, on the other hand, depends on the variety and is approx. 40 centimeters for the tall species.