Irises
Common Names: Roof Iris, Dwarf Crested IrisLatin Name: Iris Tectorum, Iris Cristata
General Info
We have two types: the larger Japanese roof iris and the small dwarf crested iris.
For both, we need to watch out for the iris borer. It's a moth whose caterpillars really destroy the irises, especially by eating up the rhizomes and causing root rot.
- Rhizomes!
- Flower briefly in spring or early summer.
- Since the roots can quickly take all the nutrients of the soil, division and re-planting is needed every other year,[8][25] or every 3–5 years when clumps become over-crowded.[4][14][17] Although, it can be left undisturbed for many years, but flowering will decrease.[39] They should be spaced 20–30 cm (8–12 in) apart. Division is best done in the spring,[10][37] or fall (after flowering).[12][10][28] Transplanting should be carried out soon after division.[26]
- Should divided every 3-4 years. The rhizome should be split into hand-sized clumps to allow for plenty of new growth to occur. The new plants should be kept moist until established
Roof Iris (Iris Tectorum)
- A mulch can also be applied (at the same time) to retain the moisture.
- Don't mulch these guys says one source.
Crested Iris (dwarf?) (Iris cristata)
- seedlings take 2 or 3 years to flower.
- Once established in the garden, these little gems require hardly any care. In fact, they pretty much take care of themselves. Other than keeping the soil moist, which can be helped along by providing leaf mulch, you really don’t need to do much else. And as long as the soil is relatively fertile or amended with organic matter, there’s no need for fertilizer either.
Soil Requirements
- slightly acidic, but neutral is prolly fine. pH 6-6.8.
- Moderately rich, well-drained soil, amended with sand or leaf mold.
Water Requirements
Average, nothing too special.
Fertilization
Roof Iris (Iris Tectorum)
- During spring or autumn, a top dressing of well rotted compost (or well rotted manure),[11] should be added,[8][37] a feed of fertilizer can also be added.[11][17][28]
Crested Iris
- Crested Iris tolerates low fertility, and clumps lose their density when over-fertilized. We recommend against fertilizing at planting time and during the first growing season in your garden. Plants need time to settle in before being pushed to grow. Most established plants grow best if fertilized with a light hand. We fertilize perennials just once -- in early spring -- with a light but even coverage of a balanced, granular fertilizer (such 10-10-10 or an organic fertilizer). If a concentrated, water-soluble fertilizer is used, please follow the manufacturers' recommendations carefully.
Pruning
- Should snip them back to just a bit above the ground in the fall?
Seasonal View
Spring
- Compost or fertilize lightly.
- Should flower briefly.
Fall/Winter
- Perhaps get rid of some dead leaves and such around that can host various insects that will mess up our rhizome.