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Given the numerous variations, the iris is one of the most diverse garden perennials. With their filigree flowers, they are a treat for the eye. A distinction is made between rhizome and onion irises. While a rhizomiris forms a subterranean shoot axis system (rhizome), the outlasting organs of the onion iris consist of tubers, which are incorrectly called bulbs. It grows in the garden bed or as a swamp and water dweller. As a result, there are a few things to consider when planting the iris.

plant irises

There are a few things to keep in mind when planting irises. In the following article you will learn everything about planting irises: from the right planting distance to the perfect time.


  • prefers sunny to light-shaded and wind-protected locations
  • Should not be constantly exposed to the sun
  • Especially not in the blazing midday sun
  • At best, about six to eight hours of sun a day
  • Bearded, steppe and small net leaf irises are among the warmth-loving species
  • Most rhizome and bulb irises sensitive to moisture and moisture
  • Consequently, increased planting beneficial
  • For example on a slope or in a raised bed
  • Ensures better water drainage
  • With the exception of the beardless meadow and swamp irises
  • Plant meadow irises in fresh to moist places
  • Swamp iris needs swampy to wet locations
  • pH rather slightly acidic than too calcareous
  • Marsh iris thrives best in water depths of up to 20 cm
  • Also tolerates depths of up to 40 cm
  • Then usually fewer flowers

With the exception of the moisture-loving irises, the others require loose, well-drained, sandy/loamy or loamy or rocky and calcareous soil. Plenty of sand, humus or compost should be worked into soil that is too heavy before planting to improve its permeability. Once the soil in the planting area has been thoroughly loosened, all soil obstacles such as root remains, stones and weeds are removed. Now he is optimally prepared, it can be planted.

tip: If you occasionally loosen the soil with a digging fork, this benefits plant growth. However, you should proceed carefully so as not to injure the sensitive roots.

Planting irises: instructions

onion iris

Before planting, it is advisable to sprinkle some horn meal. Then you can usually do without additional fertilization. You should avoid fresh manure and artificial fertilizers, they are poorly tolerated by these plants. To plant the bulbs, first dig small holes about five to ten centimeters deep, depending on the size of the bulb. The onions are placed in there, possibly on a thin layer of sand. Then you cover them with soil and press them down lightly. Finally, the whole thing is watered.

tip: The bulbs should be stored in a cool, dry place until they are planted.


The soil, which has been loosened up to a depth of 20 cm, is first mixed with some compost. Then cut the roots down to about a hand's breadth. The leaves are also cut in half to reduce evaporation. Then dig large planting holes for the rhizome. They are planted so deep that about a third of it sticks out of the ground, because the rhizome needs exposure to light and air to keep it from rotting. After you have pressed the earth, it is poured on, but not too much.

tip: In particularly hot regions, it can make sense to cover the rhizome with a layer of soil no more than 2.5 cm thick. Otherwise it could dry out easily.

marsh iris

As already mentioned, the marsh iris prefers damp to wet locations, ideally in a water depth of between ten and twenty centimetres. This can be in a swamp bed, a wet zone and at the edge of a pond as well as in an artificial stream. If you want to prevent irises from spreading too much, you should put them in a special plant basket.

It is first lined with fleece and then filled with commercially available bog soil. The iris is placed in there and the substrate is weighed down with small stones to prevent the soil from being washed out. Finally, you put them together with the basket in the water at the appropriate depth. Of course, the distance between the individual plants also plays a major role.

tip: In order for the marsh iris to thrive optimally, it needs a portion of humus every spring.

plant spacing

  • Planting distances of irises depend on the respective variety
  • For tall varieties, such as the tall bearded iris, plant 40 cm apart
  • About five to seven plants per square meter
  • Medium varieties, planting distance of about 30 cm
  • Approx. 25 cm in low-growing species
  • Or 12 to 16 pieces per square meter
  • If possible, do not plant irises too densely
  • Could otherwise grow into each other after a few years
  • The result would be competition for water, nutrients and soil
  • stunted growth of plants
  • Marsh irises need a distance of 40 to 50 cm
  • Arrive in small tuffs of up to six specimens, at their best

tip: If the flowering stops after a few years, it is advisable to divide larger pieces of rhizome. You should make sure that each section has roots and a well-developed tuft of leaves.

Best planting time

The best time to plant bulbous irises is, similar to crocuses and daffodils, in late summer or early fall, i.e. September or October. Planting is also possible in November or in spring, around March. Specimens that you want to cultivate in a pot do not require a specific time, they can usually be planted all year round. However, irises usually do not thrive so well in pots.
Planting in late summer or early autumn is ideal, then the iris has the chance to form and grow enough roots before the first frost. In addition, there is still enough sunlight to support the growth of the iris, which in turn makes it easier for them to overwinter. In contrast, the marsh iris has the best starting conditions when planted between July and September. If you missed the right time, you should wait until spring, around April/May.

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