|
|
How to Grow Irises
Today’s bearded irises come in a spectrum of brilliant colors, and an array of
special effects. They’re one of the easiest perennials to grow, rewarding you
with beautiful, dramatic, outstanding blooms, year after year! Proper care is
relatively simple, minimal, and the results are always a visual gift!
When To Plant
Irises need a minimum of six weeks of active growing time before a severe
freeze. In Texas we plant bare root rhizomes in September and October with
great results because our winters are very mild. Most gardeners know their
“zone” and average freeze dates. Back off six to eight weeks and you have your
proper planting time. In Northern states, planting would most likely begin in
July or August.
Where To Plant
In most climates irises do best in full sun all day. In extremely hot climates
like Texas (102 degrees), some shade is quite beneficial. Please make sure your
plants receive at least a half to two-thirds of a day full sun if you wish to
see blooms. |
|
Since I have the forum to editorialize, in my opinion, one of the least
desirable places to plant iris is under a tree – and I see it time and again. As
the tree grows, so does the shade factor. Need I say more?
Planting In Your Zone
Below you will find a link to The 2001 US National Arboretum "Web Version" of
the USDA Plant Hardiness Zone Map USDA Miscellaneous Publication No. 1475,
Issued January 1990. Irises grow very well in the United States, except in
Florida, Arizona and Hawaii where the foliage will be lush but the likelihood of
blooms is very low. We don’t wish to reinvent the wheel, so please link over to
this wonderful map and discover all you need to know about your hardiness zone –
it’s an exceptional site.
www.usna.usda.gov/Hardzone/#details
Soil Preparation
The ideal soil pH for irises is 6.8, which is slightly acidic, yet if any plant
is more forgiving, it’s irises – they’ve very tolerant in many respects. If you
wish to adjust the pH of your soil, add lime for acidic soils and sulfur for
alkaline soils. We recommend analyzing your soil first before undertaking
corrective measures.
At Wild Prairie Farm we are blessed with sandy-loam soil, so we only add compost
and organic matter. Before this location, our soil was what Texans describe as
“black-gumbo”. We were always adding and amending to loosen it up! If your soil
is thick and dense, add course sand and organic matter to improve the drainage.
Many folks add gypsum to improve and condition their clay soil.
Raised Beds
Planting in a raised bed will yield great results and planting on a slope will
ensure good drainage. At Wild Prairie Farm we plant on slopes, in raised beds
made with railroad ties, and mounds in some places. |
 |
Depth To Plant
A common mistake is to plant irises too deeply. For most soils, irises should be
planted so the tops of the rhizomes are exposed and the roots are spread out
facing down in the soil. In loose, light soil, like our sandy-loam, or in
extremely hot climates (parts of Texas), covering the rhizome with one inch of
soil is desirable. Once planted, wet-in (water) the soil so it will settle
around the roots.
|
|
Distance Apart
For an immediate effect of abundance, plant six inches apart and be prepared to
thin the clumps every year. Plant twelve inches apart to allow the iris to grow
and stretch, and thin every two to three years. To have a longer-range plan for
thinning, plant twenty-four inches apart. Decide what your desired effect is and
plant accordingly.
Planting In Layers
Wild Prairie raises mostly TALL bearded iris, but we do have a handful of medium
and border iris. When we plan our display beds, we plant the tall iris at our
focal point and stagger the shorter sizes in layers towards the front of the
bed. This also creates a vision of abundance and fullness. |
|
Potted Plants
Yes! Irises make beautiful potted plants! When thinning out your clumps in the
fall, consider planting your increases in pots with good drainage. Be sure your
container has enough depth to support the roots. Water only when the top two
inches of the soil is dry being careful not to over-water which leads to rot.
Gussie-up that container with a ribbon and you have a fabulous gift to give a
friend as an introduction to the wonderful world of irises!
Watering
Irises are VERY drought tolerant! Over-watering is THE most common error. Newly
placed rhizomes need moisture to help their roots become established. Specific
watering instructions depend on your climate and your soil type. Shallow, more
frequent watering is not desirable. Deep watering at longer intervals is much
better. Once established, irises generally do not need to be watered except in
hot, dry areas. Irises do not respond well to sitting in water, which is why you
will always hear iris people talking about good drainage.
Fertilization
First and foremost, avoid using anything high in nitrogen - this promotes rot
problems. When planting, use superphosphate, bone meal or 6-10-10 mixed in the
soil under the rhizome. Apply to surface area, after the initial planting for
good bloom and vigorous growth.
Here at Wild Prairie we also use Alfalfa Meal in the same way as superphosphate.
A speaker recently at the Iris Society of Dallas shared that she uses Alfalfa
Pellets for her aribred iris farm in Lubbock.
Here in Texas we fertilize in mid-February (two months before bloom time), late
May (after bloom time) and at replanting time in September and October. At a
Fort Worth Iris Society meeting recently, one woman said the way she remembers
to fertilize is Valentines Day, Memorial Day, and Halloween. Pretty catchy way
to remember!
And by the way, may I please encourage you to join an iris society or garden
club – I personally belong to six. The speakers are fascinating, presentations
are always informative, and member enthusiasm is very stimulating. Most folks in
the iris business will tell you that it all started as a hobby – even large
growers tell a similar story!
Crowding and Thinning Clumps
Irises become crowded as they grow, which is why you need to decide how
far apart you wish to plant them originally. When this happens, some
varieties will crowd out other varieties, any minor disease problems will
become bigger, and blooms will suffer tremendously. |
 |
So divide and conquer! Dig up the entire plant. You’ll be amazed with the
size and multiple directions of the growth. The “spent” rhizome will be
obvious at the center of the clump and should break away rather easily.
Look for where the roots and root nubs are – this is the increaseyou will want to replant. I have broken off as many as five increases from
a single vigorous iris plant from one season – so inspect the clump carefully,
looking for roots to help indicate where active growth is. And rhizomes aren’t
always long and tubular at the active growth – some are more like a toe – if any
part of the rhizome snaps away easily, then it is “spent” – time to compost!
We always trim the leaves in a chevron shape of our freshly snapped increase, so
when we replant, there are little green flags everywhere indicating where they
are planted. We also write the name of the iris on the leaves with a Sharpie
(permanent marker).
Now replant the newer growth! If you need a couple of days to dig your iris up
and decide how you will replant, don’t despair. Your rhizomes will be fine out
of the ground for several days as long as they are not wet or sitting in a
puddle.
Relocating to a new home! Yes, you can take them with you! Trim your roots and
leaves, write the name of the iris on the leaves with a Sharpie (permanent
marker), wash and air dry. When dry, place your rhizomes in a cardboard box or
paper bag with loose packing materials – like paper from your shredder. Your
rhizomes will be fine for three to four weeks until you can replant them – as
long as they stay dry. If the weather is too hot or too cold, pot your rhizomes
and wait until the temperature changes before planting in the ground. The sooner
they’re planted the better.
Garden Care
Allow the tops of the rhizomes to bask in the sun by keeping beds clean of
weeds, debris and leaves. Stems should be cut off close to the ground after
blooming. If any leaves appear brown or diseased, remove them close to the
ground. Otherwise, the leaves should be left undisturbed so the rhizome will
receive healthy nutrients.
Types Of Bearded Iris
TB — Tall Bearded Irises are the big kahunas of the iris world, with incredibly
large blooms displayed on stems over 28 inches tall, extending to approximately
40 inches tall, with branching and many buds. Each stalk, in itself, makes a
stately arrangement in the garden or in a vase. In addition to a wide variety of
colors and patterns, the tall bearded iris displays other qualities, such as
ruffling and lacing, more frequently than do the other classes.
IB — The Intermediate Bearded Irises reach a height of 15 to 28 inches and mix
exceptionally well with other plantings. Although the IBs show their dwarf
ancestry in early bloom season and very interesting color patterns, they are
large enough that their individual stalks may be nicely branched, forming an
elegant bouquet. Some varieties are nicest in clumps where they present a large
amount of color, while others are showiest in specimen plantings where the
stalks and individual blooms maybe seen to best advantage.
BB — The Border Bearded Irises reach a height of 16 to 26 inches and mix
exceptionally well along borders and edge planting. Essentially these are
smaller versions of the TBs in the same height range and bloom size as the
intermediates, but blooming with the tall beardeds. Good BBs have round, ruffled
petals that complement their small size.
MTB — Miniature/Dwarf Bearded Irises range in height from 5 to 15 inches and are
wonderfully suited for borders and edge planting. They begin their bloom quite
early in iris season and they are best displayed in clumps where they give the
effect of a “cushion” of individual blooms.
Companion Planting
It’s so very personal! I mix iris with day lilies, cosmos, stock, rosemary,
roses, floxglove, coreopsis, and a variety of other wonderful bloomers. Texture
and color is my guiding light.
Interesting enough, I find that combining iris, amaryllis, day lilies, and
cannas creates a blooming wave of events in the order I have listed. As one
bloom group fades, the other begins. I like it.
Winter Protection
In areas with cold, snowy winters, we recommend covering newly planted Iris with
hay, straw, pine needles or leaves. Remove the cover as early as possible in the
spring so the sun can warm the rhizome and prevent rot.
Weed Killer
Chemicals that kill weeds will also harm iris. Hand weeding is the best
preventive measure.
Back
|
