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Irises
prefer a full day of sun, but will grow and bloom well if given six or more hours
of sunlight. The best time to plant is after the Iris has finished the bloom
season and before it starts new growth. In most cases, this will be between
July and October avoiding periods of temperature extremes. The ideal time is
when the summer heat has ended and cooler fall weather arrives. For climates
with severe winters and early freezing temperatures, we recommend planting
prior to August 15. This will ensure early root development. The bearded Iris
is drought tolerant but will rot if too wet. Gardeners can avoid many problems
by providing good drainage to protect the Iris from getting "wet
feet".
When
you receive your shipment of Irises you should remove them immediately to let
them air out for a day or so before planting them. If you are unable to plant
them within a day or two lay them outside in the shade. Do not put in a closed
building where they might get too hot. Irises can remain out of the ground for
a week or two but you should try to plant within three days of receipt. Water
at planting time and keep moist but not soggy for the first month (see About
Sunlight and Water section below).
A well-prepared bed for your Irises will result in better
growth and bloom. Irises grow in average garden soils with a PH close to
neutral (6.5 to 6.8). They like loose well-drained soil since they do not
tolerate standing in wet soil. In heavy clay, we recommend raised beds or
raised rows with lots of compost. Some say that adding coarse sand is
good, but you will need to add at least 30% or you run the risk of creating
concrete. We have had very good results with compost but, as with
the sand, it takes a lot. Irises love
compost but not too much green (compost with high nitrogen content). Although
the Iris needs nitrogen, too much in the wet seasons will promote rotting. You
should add compost to your bed as well as extra food (fertilizer) to promote
the very best growth and bloom of your Iris. For new planting, well-rotted manure
or well-rotted compost are good additions. A no nitrogen chemical fertilizer or
super phosphate (or bone meal) can be dug into the soil at the rate of 1/2
ounce per square foot three weeks before the plants are set in. If adding
at time of planting use 1/2 strength. It is best to double dig or rototill your
Iris bed to ensure the mixing of the fertilizer and compost before planting
your Irises.
Now
that you have your beds ready in a sunny location make a shallow hole about
twice the size of the rhizome. Take a handful of the soil you removed and make
a mound of soil in the center. Place the rhizome on top of the mound and drape
the roots down the sides of the mound. Press the rhizome down to ensure that it
makes firm contact with the soil. Any air pockets can collect water and cause
rot. When you fill the hole with soil the top of the rhizome should be at or
slightly above the surface for warm areas and slightly covered for areas with
freezing winters. Remember that it is always better to have the rhizome too
high rather than too deep.
Irises
do best in full sunlight but will do well in slight shade. That is to say, they
should have a good six (6) hours of sunlight a day. In areas of extreme heat
and little water, some shade is good. There are three times when the Iris needs
water. When the Iris is first planted until the roots have taken hold. At this
time the soil should be moist but not waterlogged. You will know when the roots
have taken hold by the new center leaves coming up. This usually takes 2 to 4
weeks. Once established you should reduce the watering until the winter or fall
rains set in. During dry spells (over three or four weeks long) you will need
to give them a good deep watering every 3 to 4 weeks depending on the
temperature. The second time the Iris needs water is in the early spring. In
almost all areas, “Mother Nature” will take care of this for you. In a rare
case that you have no rain or snow and hot temperatures in the spring season,
you should supplement the watering every other week. The third time is for the
reblooming Iris. They will need more water in order to develop stalks and
flowers in the summer and fall seasons.
Irises
should be fertilized in early spring about 6 to 8 weeks before bloom, and again
after the blooms are gone. Because phosphate is important, we recommend bone
meal or super-phosphate and a light balanced fertilizer such as 10-10-10 or
6-10-10 depending on the amount of nitrogen in your soil. The most important
part is to not use anything high in nitrogen as nitrogen promotes rot problems.
We highly recommend that you test your soil. Soil test kits can be purchased at
most hardware or garden supply stores. What you want to see is neutral PH (6.5
to 6.8), medium to low nitrogen, high level of phosphorus, and medium level of
potassium. All fertilizers will list the amounts of nitrogen, phosphorus, and
potassium on the container in that order. For example 5-10-15 tells you that
the container has 5% nitrogen, 10% phosphorus, and 15% potassium. Nitrogen is
for the green growth such as grass. Your grass fertilizer is probably 25% or
higher in nitrogen. Don’t use it on your Iris! Phosphorous promotes root
development and since the rhizome is all root, it needs lots of phosphorous.
Potassium improves the overall health of the plant, defends against diseases
and helps plants withstand very hot or cold weather. In the fall it is a good
idea to add bone meal or super-phosphate or both or fertilizer with no nitrogen
such as 0-10-10.
Irises
are very hardy plants and really do not need a lot of attention. Keep your Iris
beds weeded and remove old dried leaves. This will provide air circulation.
After blooming, cut the flower stalks as close to the ground as possible. This
will help the Iris to concentrate its energy in new growth production.
We
recommend dividing your Irises after about 3 to 4 years as they become too
crowded. The Iris needs room to grow new plants. If over crowed, they will be unable
to divide and the bloom will suffer or stop. Over crowding also promotes
disease problems from lack of air circulation. The best time to divide your
Irises is about 6-8 weeks after bloom season, usually in July or August. Clumps
can be thinned by removing the centers of the clumps leaving the newer growth
in the ground or by digging the entire clump and saving the new rhizomes and
discarding the old “Mother” plants or any rhizome that is not healthy or is
soft. It is a good idea to keep all your plants carefully labeled when removing
the entire clump. You can use a waterproof marker to write the name on the leaf
of the plant. After digging your Irises, divide them by cutting the newer
rhizomes with fans attached.
Above
is the textbook guide to planting and maintaining your Iris. The truth is, the
Iris is a very tolerant plant. When we purchased our ranch we were given
about 500 Iris to line our 600-foot driveway. At the time we were remodeling
the 100+ year-old house and had very little time to spend on the Iris
planting. As it turned out we did very little in following the “correct”
way to plant Iris rhizomes. We did not plant the Iris for over three months and
were not sure if they were still alive when a family member volunteered to
plant Iris rhizomes for us. The area we had to work with is in the foothills
and is almost 100% clay soil. We did nothing to amend the soil, just dug a
trench with the garden tractor and put the Iris in the trench and kicked and
pushed the dirt over the Iris. The driveway is eucalyptus tree lined without
the required 6 hours of sunlight. Besides that, nothing is supposed to grow
under a eucalyptus tree. I think that first summer we only watered once, even
in the months with temperatures in the high 80’s. Later in the summer I
purchased some Iris from the local hardware store (you know, the kind in little
bags that are dried out and take years to flower) and planted them myself
knowing nothing of how to properly plant them. About the only thing I got right
was to put the roots down. I planted them in an extremely wet area (a bog
really) during the rainy season and I planted them way too deep.
If you
have any other questions about your Irises, please feel free to E-mail us,
orders@www.walking-p-bar.com,
and we will gladly answer your questions relating to this bearded iris planting
guide and iris gardening guide or any iris planting questions you may have
about our gardening guide.