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Iris X hollandica
Dutch iris, Iris X hollandica, are gorgeous, elegant cut flowers. They’re spring blooming and grow from a bulb whereas most other irises grow from rhizomes.
They come from a species of iris from Spain and Portugal and were hybridized with a variety of other native irises by a group of Dutch people to create a new, larger flower. Appropriately, they were named I. X hollandica, and the common name became Dutch Iris. (When an x appears between the genus name and the species name it represents a hybrid of two or more species resulting in a new species.)
And it keeps getting further improved to offer a variety of colors.
It’s also called the ‘Fleur-de-lis’ bulb, and bulb iris.
These simple, elegant iris flowers come in blues, deep purple, white, yellow, and some reds. The flowers are about 3-4 inches across. They have “falls”—downward pointing petals— that have a stripe of bright yellow.
With the right care the cut flowers should last 5-7 days. Some stems contain two flowers, so when the first one fades, it can be removed and the next one will open giving a longer vase life. See more on the right care in “Harvesting”.
The long, slender foliage, as elegant as the flowers, grows to 18-25 inches tall and is a grayish-green.
The plants are purportedly deer and rodent resistant. I’ve always grown mine in a deer-fenced garden so I can’t attest to that.
They need well-drained soil and dry summer soil. With this they can perennialize so you don’t have to replant each year. Otherwise they need to be lifted and stored when they go dormant.
Growing the plants
Bigger bulbs yield bigger flowers, so try to get the bigger ones if you can.
Bloom times are usually listed for the colder zones. Warmer zones give an earlier bloom, and the foliage will emerge in late fall or early winter, but bloom in early spring. In colder zones the foliage emerges in early spring.
When to plant
Dutch iris can be planted at the same time that you plant daffodils, tulips, and ranunculus, which for me in (USDA Zone 8) is in November.
In warm areas the foliage will start growing in late fall or early winter but the flowers will come in the spring. In colder areas the foliage won’t pop up till spring.
If you’re in an area that gets bitter cold spells, once it’s cold in late fall, cover them with a 2 inch layer of straw, leaves, or something similar. The idea is to keep the cold in but to prevent damage from excessive cold
Where to plant
Plant in full sun (which is at least 6 hrs. of full, direct sun) or they can take a little shade. But they live longer and flower best in full sun.
Plant in well-drained soil. They don’t like to stay wet and soggy. If you want to keep your bulbs in the ground for the next year, be sure to choose a planting location where the soil will be warm and dry through the summer.
How to plant
Prepare the soil by loosening it and add composted organic matter. Use well-composted manures, finished home compost, or a quality bagged compost. I apply good quality compost on top of the soil then use a digging fork to loosen, but not turn, the soil. In the process the compost trickles down deeper.
Plant them 4-6 inches deep (measured from the top of the bulb), pointy end up, and 3-4 inches apart. The folks at John Scheepers recommend planting 6” deep if you plan to keep them in the ground and perennialize them. They also suggest only fertilizing them over the soil after planting and not in the planting hole.
Fertilizing bulbs is a good idea. Many people suggest fertilizing at the bottom of the hole at planting time. But many others suggest applying fertilizers on the soil after planting. There are three times to fertilize: right after planting, or for perennialized bulbs, in the fall; in the spring when the sprouts emerge and are growing; and again after the flowers are spent, or harvested, to feed the bulbs.
The best fertilizers are organic, and have the NPK numbers of 5-10-5 or something similar. The middle number is the phosphorous which supports root and bud formation and growth.
After cutting the flowers (see Harvesting for details) the leaves keep feeding their bulbs for the next year’s growth, so let them die back naturally. Once they’re all died back you can remove them to tidy up.
The bulbs that are left in the ground to perennialize should stay pretty dry in the summer. If you must irrigate the area in the summer, or if you have rainy, wet summers, you will need to lift the bulbs when they’ve died down, store them in a cool, dry place, and replant them in the fall. Otherwise the bulbs will rot.
To lift and store the bulbs, dig them up the when they’re dormant, brush off the soil, and store in a mesh bag, like an onion or orange bag, and place in a cool, dark, dry place with good air circulation. Apply soil sulfur or antifungal powder if they might get moldy. Check them periodically for mold or rot. Remove bad ones as soon as possible.
I plant my bulbs all in one bed devoted to bulbs that need, or can take, dry soil for the summer. That way they stay dry and I save water in that area during the summer and focus on other plants and vegetables. My current purpose is for cutting flowers rather than landscape beauty. (Although, beauty happens anyway!)
These irises like moisture during their growing season fall through the spring bloom. Water them if rain or snow fails.
Each year the bulbs produce little side bulblets. These will eventually grow to full size to give you more flowers, but it takes a few years for them to mature. So if you are able to leave the bulbs in the soil, you’ll be able to easily increase your Dutch iris patch!
Cut the flowers when a line of color 1½ to 2 inches long along the bud is showing.
Place flowers in water to condition and recut at an anle to desired length to place in your vase.
The right care, to improve the vase life, involves cutting the stem at an angle and putting it into water immediately. After a conditioning period, cut again, at an angle, to the desired length and put into the vase.
For best results, give it flower food. The best food for Dutch irises florists recommend is Pokon Chrysal bulb food. But any cut flower food will help. For a quick homemade food, dissolve ½ tsp. of sugar, 1 tsp. of lemon juice, and a few drops of bleach in 4 cups of water. Use straight or mix with water in the vase.
The buds are pretty and they will open in the vase. When the first one fades, cut it off and the next will open.
Check vase water regularly and change if it’s getting cloudy.
How Many Plants
Packages of bulbs can be in sizes from 12 to 24. This is a great number to start with.
I have no favorite varieties so far. I like to buy the common mixes available in nurseries.
Available in the fall for planting, I always recommend first buying from your local nursery—supporting local businesses should always come first. The usual mix is called rainbow colors.
But many nurseries won’t have packages in single colors or they may not have a special variety. Here are some good sources I’ve dealt with in the past.
John Scheepers at https://www.johnscheepers.com/flower-bulbs-index/dutch.html
Dutch Grown at https://www.dutchgrown.com/collections/iris They have a beautiful selection of single colors.
Dutch iris is often called the fleur-de-lis flower because many historians believe the fleur-de-lis icon was derived from one of the wild irises that went into the hybridization of the Dutch iris. But still other historians believe the icon is based on a lily flower. The symbol has been used by the French for centuries and has denoted royalty.