How To Grow Iris: Tips For Dutch, English And Spanish Iris Bulb Planting
By: Heather Rhoades
When learning how to grow iris plants like Dutch, English and Spanish irises successfully in the garden, correct iris bulb planting is important.
When and How to Grow Iris
You should plan on planting iris bulbs like these early in the fall. These small bulbs have a rough tunic on the outside. The bottom is the part that has the flattened basal plate, so obviously the top is the opposite end.
Group Planting Iris Bulbs
In groups of five to 10 bulbs in a nice flower border, plant Dutch, English and Spanish irises. Each group of bulbs should be planted next to perennials such as peonies. This arrangement helps hide their foliage when it withers away.
Iris Bulb Planting
Follow these steps for growing Dutch, English, and Spanish irises in the garden:
- Choose a site that has reasonably fertile soil and plenty of moisture. In other words, you want soil that won’t dry out in summer. Dutch and Spanish irises have a habit of producing leaves in autumn and winter, so they need a sheltered environment. Good drainage will help them survive the winter.
- You should buy the bulbs early and plant them as soon as you can in deep soil, with about 5 to 7 inches of soil over the top of the bulbs. Dutch irises are an exception to the early-planting advice.
- Dutch and Spanish irises, are best lifted and stored out of the ground over the summer. This means you need to dig them up and store them in a cool, dry place. Lifting them provides the dry resting and ripening period they need for a great flowering season the following year. Don’t sun-dry them; storing them in a well-ventilated place is perfectly fine.
- Then, simply replant them in late fall.
Now that you know the basics for how to grow Dutch, English and Spanish irises, you can get started on your iris bulb planting for enjoyment each season.
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I have sprinkled some bulb fertilizer on top of the soil. This is optional, it is said to help but can attract critters, usually, it has a bone meal base that is irresistible to wildlife.
Stir the fertilizer into the soil, mixing it in lightly. I mix the fertilizer in to the soil rather than just placing in the hole.
Rain fall will deliver the fertilizer where it needs to go.
NOTE: If you struggle with varmints digging up things in your garden then skip adding any fertilizer. Many times it contains bone meal and that attracts them to dig. Most of the time the fertilizer is unnecessary anyways and you will have success without it, I know I did. Healthy rhizomes should have stored plenty of energy to the coming bloom.
Planting Iris Bulbs in Spring
Irises bloom in early summer adding a splash of color to perennial beds before many other flowers are in bloom. Grown from underground rhizomes, often incorrectly referred to as bulbs, irises are typically planted in late summer or early fall. However, rhizomes planted in the spring often bloom in middle to late summer and return in the spring. Regardless of when they are planted, preparing the soil properly in a sunny location is necessary.
Prepare the soil in a sunny, well-drained area. Till the soil with a garden tiller to a depth of 8 to 10 inches. Remove roots, rocks and other debris from the soil. Break up clods of soil with the blade of the hoe or spade.
- Irises bloom in early summer adding a splash of color to perennial beds before many other flowers are in bloom.
Spread a 2- to 3-inch layer of well-rotted manure or peat moss over the top of the soil. Work the organic matter into the soil with a garden tiller or hand tools. Rake the area smooth.
Apply 2 lbs. of 5-10-10 fertilizer per 100 square feet of gardening area. Mix fertilizer in with the existing soil to avoid injury to roots. Fertilizer should not touch roots or rhizomes.
Dig a shallow hole, 2 to 4 inches deep, that is large enough to accommodate the rhizome. Mound the soil in a ridge in the center of the hole.
Place the iris rhizome on top of the ridge of soil, with roots extending over the sides of the ridge and pointing downward. Position the rhizome so that the top of the rhizome rests just below the surface of the soil. Fill in around the rhizome with soil and firm down with your hands.
Water thoroughly to moisten the soil to the root level. Keep the soil moist until new growth appears. Reduce watering to once a week, saturating the soil to the root level each time you water.
- Dig a shallow hole, 2 to 4 inches deep, that is large enough to accommodate the rhizome.
- Place the iris rhizome on top of the ridge of soil, with roots extending over the sides of the ridge and pointing downward.
Irises thrive in soil with a pH between 6.0 and 7.0.
Caring For and Fertilizing Irises
Although iris do not need a lot, a small serving of specially-designed iris fertilizer can make your display grow even stronger and healthier. Breck's ® Iris Lovers All-Natural Iris Food uses a 4-4-2 ratio of nitrogen, phosphorus and potassium, respectively. Our iris food is well-balanced, so your irises won't be over- or underfed. Nitrogen is vital for healthy growing, but too much can cause soft, disease-prone growth. A small dose of phosphorus is useful when producing flowers and developing roots, and some potassium helps bring out those rich, vibrant colours that make iris so lovely. Our iris fertilizer has less phosphorus and potassium than our other fertilizers, and just enough of all three key nutrients to give your bearded beauties the boost they deserve! If your asking yourself "why are my irises not blooming" apply Breck's Iris Lovers fertilizer or check the depth of your rhizome. Iris planted too deep or iris planted in full shade will cause it not to bloom.