Bearded Iris really offer so much to the mixed perennial garden. The beauty they offer in the spring is uncontested, but we often get questions about what to do with the foliage after the spring bloom has faded. Culturally speaking, the foliage must remain intact through the summer growth phase. The foliage converts the energy to feed the growing rhizomes. Shorter foliage can limit the energy conversion. That said, we ourselves trim the foliage when we prepare our plants for order fulfillment. This practice of trimming foliage is also generally followed when gardeners divide and transplant Iris in their home gardens. The shorter foliage facilitates planting — the long blades of the Iris foliage can often prove too heavy for the newly planted rhizome to bear, causing the plant to become dislodged. Established Iris, of course, with their larger root systems, can bear the weight of the foliage.
Thus, we recommend leaving the foliage untrimmed throughout the summer months. Planted among other summer blooming perennials and shrubs, the vertical lines of the Iris foliage provide a wonderful counterpoint to other forms in your garden. The images here illustrate this point. These photos were taken in our Display Gardens in late July.
Iris bed in mid-summer. Vertical lines contrast with shorter annuals and greenery.
Summer days, summer gardens. Most enjoyable. For the Tall Bearded Iris in your garden, summer is also the perfect time to grow, to expand, to be transplanted.
Bearded Iris experience two root growth cycles in their annual growing cycle. The springtime growth we all eagerly anticipate in our Iris beds begins with the lengthening of the foliage upward and the root system outward. The rhizome uses its stored-up nutrients.”….As the bud swellings appear in the new fans there is a quickening of the new roots that will supply the plant with nutrients for new growth during and after bloom. The old roots from the previous year’s growth then wither and decay.” ( The World of Irises, p 314) After the springtime color display of full bloom has passed for the year, the underground development begins in earnest.
The Iris revel in the long summer days. During the six to eight weeks post bloom, the plants absorb the necessary nutrients for next spring’s growth and bloom. The rhizomes send out new increases which will become new self-contained, self-supporting rhizomes by early to mid-July. Once the summer growth is complete, the Iris takes a well-earned rest. Enter the gardener, spade in hand, plan in mind. Now is the time to dig, divide, share and transplant.
Here, in the Willamette Valley our Iris bloom season ends early- to mid-June. Therefore, at Schreiner’s Iris Gardens, we begin digging our fields early to mid-July. On a smaller scale in your garden, consider digging your Iris to transplant this summer if the clump is three to five years old. Share the divided Iris not only in your own garden, but also with the neighbors, friends and family….garden clubs, retirement homes, 4H clubs, and so on. Allowing Iris clumps to become over grown can lead to poor or no blossoms, smaller and smaller rhizomes, and outbreaks of rhizome-based diseases (such as bacterial soft rot).
Remember that the latest date for transplanting depends on local conditions. Newly planted Iris require a minimum of 6 weeks to set their new roots. Thus, they should be in the ground a minimum of six weeks before the first hard frost. Consult local resources to determine the frost dates in your area.
What’s happening in the July garden? To trim or not to trim the foliage…Depending on your location, you may have a handful of lingering Iris blossoms, or all of your bloom stalks might be sporting the papery remains of the seasons’ blooms. When all blossoms on the stalks have finished, carefully trim the bloom stalk at its base. Leave all green foliage, though, in place. They offer an elegant vertical visual throughout the garden. You may remove any browned and dry leaves. Keep the Iris beds clean and free of weeds. Well-established Iris plants are drought tolerant. Newly planted Iris, though, do require a good long drink approximately every 7 to 10 days if the weather is very dry. Reblooming Iris also prefer irrigation between the spring bloom and summer/autumn re-bloom times. We recommend an application of a low-nitrogen fertilizer (such as 6-10-10) approximately one month after blooms have finished. Superphosphate and bonemeal also work well as a fertilizer for Iris.
Summer brings the promise of long days enjoying our gardens and all aspects of our lives. The season also brings with it our annual Summer Sale. You’ll find over 300 varieties of Tall Bearded Iris at deeply discounted prices.
The summer solstice, a most propitious date — brings the promise of long, heady days of summer, reaping the success in our gardens and in all aspects of our lives. June 21st also heralds the start of our 2014 Summer Sale. You’ll find over 350 varieties of Tall Bearded Iris at deeply discounted prices. Pictured on the cover of our summer sale catalog below is a special bonus for your summer sale order. “Swept Off My Feet”, one of our 2014 introductions, is the 2014 Summer Sale bonus. Use coupon code SSC2014 to get yours. (*Limit one per customer; minimum $25 order of plants.)
What’s happening in the June garden? Depending on your location, you may have a handful of lingering Iris blossoms, or all of your bloom stalks might be sporting the papery remains of the seasons’ blooms. When all blossoms on the stalks have finished, carefully trim the bloom stalk at its base. Leave all green foliage in place. They offer an elegant vertical visual throughout the garden. You may remove any browned and dry leaves, though. Keep the Iris beds clean and free of weeds. Well-established Iris plants are drought tolerant. Newly planted Iris, though, do require a good long drink approximately every 7 to 10 days if the weather is very dry. Reblooming Iris also prefer irrigation between the spring bloom and summer/autumn re-bloom times. We recommend an application of a low-nitrogen fertilizer (such as 6-10-10) approximately one month after blooms have finished. Superphosphate and bonemeal also work well as a fertilizer for Iris.
Winter Iris Care Does your Iris bed look like this right now…. under a foot of snow? Iris beds covered in a blanket of snow need no care at this time. Let nature’s insulator do its job.
Or maybe they look something like this….a tangled mess of decayed leaves? Well, even though it’s not an ideal sight, don’t be ashamed. Let’s talk about how to remedy the situation.
If you have a garden that boasts bare ground right about now, you most likely are also starting to see signs of spring – along with the darling and beloved daffodil, tulip and hyacinth shoots, weeds and grass blades are also emerging. Now is a good time to dote upon the forgotten Iris bed, and trim back the dead, decayed foliage. If the leaves are droopy, brownish-gray — completely lifeless — then gently tear them off at the base, like a sheet of notebook paper from its spiral. If the leaves are still sturdy and green, trim those down to below any evidence of leaf spot.
Clear away the debris from the beds, pick out the emerging weeds, if any, from the soft soil. You might spray a preventative fungicide at this point, as well. Follow all manufacture’s recommendations carefully. If you anticipate another freeze in your area, you can lay evergreen boughs or straw over your newly-cleaned out Iris beds for added protection until the spring temperatures return in earnest. At which time, you will remove any covering. Remember, rhizomes grow close to the surface and want to feel that sunshine. Bearded Iris can be very forgiving, largely due to their very sturdy nature.
Bulbs vs. Rhizomes
Just a short two bits on the distinction between two of the methods herbaceous perennials (including Bearded Iris) utilize for food storage…. Plants have evolved several methods of storing food so that they can spring to life when the conditions are right, bulbs and rhizomes among them. The definition of a bulb is any plant that stores its complete life cycle in an underground storage structure. The “food” is converted sunshine, collected through the leaves through photosynthesis, and carried into the “larder”. Only some of the plants commonly called bulbs actually are bulbs. Bearded Iris, although falling into the above definition, develop a storage structure known as a rhizome (really an underground “stem”). The rhizome is the larder for nutrients that give the plant the energy it needs to grow, bloom, and complete its life cycle. Trimming the Iris foliage too early deprives the plant of its food intake. Rhizomes grow horizontally just under the surface of the soil which is why they must be planted shallowly, in soil with good drainage.
Celebrate the passion of Valentine’s Day all over again during Iris bloom season. Send these five radiant Tall Bearded Iris to your sweetheart, or invite them into your own heart (and garden)* with our annual Sweetheart Iris Collection.
These five sweet beauties offer wonderful discount and a lovely array of pink, just screaming out, “Be Mine!”
Let’s say a friend told you about this patch of once-lovely Iris which has become completely engulfed by grass… (or maybe that friend is you…) You tell your “friend” that her situation reminds you of something you once read by Sara Stein*: “I appreciate the misunderstanding I have had with Nature over my perennial border. I think it is a flower garden; she thinks it is a meadow lacking grass, and tries to correct the error.”
July, August and, in some areas, September, is the time to assess the situation in your Bearded Iris garden, and rectify the misunderstanding you might have with Nature. If it’s been a few years (say three to five) since you planted your Iris, it is likely that the clusters have grown, and over-grown, themselves into a large mass of rhizomes 12 to 24 inches wide. If you are (or know of) that friend described above, fear not. If you see foliage above the blanket of grass, the Iris can be saved! Read on.
Before you reach for the shovel, though, let’s review some tips on dividing and transplanting the new Iris babies.
Iris Identity: If you have your Iris labeled, you will want to label all of its babies. Prepare tags of some sort to help you keep track of what you are transplanting and where. If you haven’t labeled the Iris in your garden, then proceed unfettered by the bondage of labels….
Digging the clumps: Depending on how densely packed the Iris clump is, you may wish to dig up the entire mass and work on it out of the ground. In the case of the clumps overgrown with grass, you’re best bet is to dig up the whole shebang. Carefully pull the soil and grass away from the rhizomes and roots so that you can see what you’re dealing with. Take care to remove as many of the grass roots as possible. Once cleaned up, you will likely find that the mass of Iris resembles a tangle of fresh ginger, or small oblong potatoes, some of which will have fresh green foliage attached.
New growth on left and right of spent rhizome
Separating the plants: The rhizomes with the foliage are the plants you will keep. Any rhizome which has no foliage is “spent”, and will not bloom again. It can be discarded. At this point, you can decide how many of these new plants you’d like to replant. Some of the new growth may yet be quite small, the size of a cherry. These are called “nubs”, and will have tiny green leaves. You can plant these, but expect possibly two years at least before you see any blooms.
To separate, carefully snap or slice the rhizomes at the junction between the old plant and the new growth. Take care to disentangle the roots so that the new plants retain their set of roots.
Cut or break off new growth from original rhizome
If the foliage on the new plant is very tall, you can trim it back to 6 inches to make transplanting easier.
Prepare soil for transplants: For the area where you intend to plant the new growth, dig up the soil 6 to 12 inches deep, remove weed sprouts, mix in some organic mulch or a low-nitrogen fertilizer (follow manufacturer’s recommendations for quantity and ratio) to give the soil a nutritional boost. Break up large clumps of soil and smooth out the area. Plant your new iris so that the roots are covered but the top of the rhizome is showing above the surface of the soil.
Water in: Water at the time of transplanting. Newly set plants need moisture to help their root systems become established. Specific watering requirements depend on your climate and soil, but keep in mind that deep watering at long intervals is better than more frequent, shallow watering. Once established, Iris normally don’t need to be watered except in arid areas. It is always better to underwater than over water. Too much water can induce rot.
What to do if you have more Iris shoots than you know what to do with: Consider donating the extra plants (labeled or unlabeled) to a nursing home, school, or community center in your area. You can also check with your neighbors to see if they’d like any of the offspring.
Getting ready to divide your Iris? Tell us what you do with the extras. We’d love to read your comments.
*Sara Stein, influential advocate for gardening with native plants, and author of “Noah’s Garden: Restoring the Ecology of Our Own Backyards” (Houghton Mifflin, 1993).
First, let’s be clear: we are referring to Bearded Iris in this discussion. The myriad of other lovely Iris varieties come with their own set of operating instructions.
Our last two blog posts generated a number of very worthwhile questions. After doing a bit of reading on the subject, I came across a couple of useful bits of information. The first is a series of photos on planting Bearded Iris, see below. These come from William Shear’s, “The Gardener’s Iris Book” (Taunton Press, 1998), page 43. How deep should the rhizome be? We are in agreement with Mr. Shear on this question. “It depends,” he writes. “In light-textured soils, it can be covered by as much as 1 (one) inch of soil, but for average to heavier soils, the top of the rhizome is best left exposed to the healthful influences of sun and air. Remember that the rhizome is a stem, not a root, and needs to breathe!” You can see in the third photo below that the top of the rhizome is still peeking through the soil.
Steps for Planting Bearded Iris, “The Gardener’s Iris Book”, pg 43.
On the subject of trimming the foliage, I found a bit of tidy wisdom, the kind you keep clipped into your pocketbook, or saved on our phone, for easy reference. This comes from, “A Guide to Bearded Irises: Cultivating the Rainbow”, by Kelly Norris (Timber Press, 2012). In his myth-busting section he addresses the question of trimming. “Myth: Bearded irises are so much work. You have to trim the foliage back every summer!” Mr. Norris reassures us that in fact this may be an “unnecessary chore”. There is no real need to trim the foliage in the summer, except that during dividing and transplanting shorter foliage eases the handling of the plants. He reminds readers that “needlessly trimming the foliage back in the middle of the season actually breaks an iris’s dormancy, kick-starting foliar production. This can take away from root mass accumulation and even from reserves meant to support flowering the next spring.”
The long and short of it is to plant shallow and leave the leaves alone. Thanks for reading and happy gardening!