When to Plant
For best results, Iris should be planted in
July, August or September. It's imperative that the roots of
newly planted Iris be well-established before the growing
season ends. In areas with hot summers and mild winters,
September or October planting may be preferred.
Where to Plant
Iris need at least a half day of sun. In
extremely hot climates some shade is beneficial, but in most
climates Iris do best in full sun. Be sure to provide your
Iris good drainage, planting either on a slope or in raised
beds.
Soil Preparation
| Iris will thrive in most well-drained
garden soils. Planting on a slope or in raised beds
helps ensure good drainage. If your soil is heavy,
coarse sand or humus may be added to improve drainage.
Gypsum is an excellent soil conditioner that can improve
most clay soils. The ideal pH is 6.8 (slightly acidic),
but Iris are tolerant in this regard. To adjust the pH
of your soil, lime may be added to acidic soils or
sulfur to alkaline soils. It is always best to have your
soil analyzed before taking corrective
measures. |
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Depth to Plant
Distance Apart
| Iris are generally planted 12 to 24
inches apart. Close planting gives an immediate effect,
but closely planted Iris will need to be thinned often.
Plants spaced further apart will need less frequent
thinning. |
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Watering
Newly set plants need
moisture to help their root systems become established.
Specific watering information depends on your climate and your
soil, but keep in mind that deep watering at long intervals is
better than more frequent shallow waterings. Once established,
Iris normally don't need to be watered except in arid areas.
Overwatering is a
common error.
Fertilization
Specific fertilizer recommendations depend on
your soil type, but bone meal, superphosphate and 6-10-10 are
all effective. A light application in the early spring and a
second light application about a month after bloom will reward
you with good growth and bloom. Avoid using anything high in
nitrogen, as nitrogen encourages rot problems.
Thinning Old Clumps
Iris need to be thinned or divided before they
become overcrowded, generally every 3-4 years. If Iris are
allowed to become too crowded the bloom will suffer, some
varieties may crowd others out and disease problems may be
aggravated. Old clumps may be thinned by removing the old
divisions at the centers of the clumps and leaving new growth
in the ground. Or, you may dig up the entire clump and remove
and replant the large new rhizomes.
General Garden Care
Keep your Iris beds clean and free of weeds and
debris, allowing the tops of the rhizomes to bask in the sun.
Bloom stems should be cut off close to the ground after
blooming. Healthy green leaves should be left undisturbed, but
diseased or brown leaves should be removed.
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