Iris bulbs, although not difficult to physically plant, require a bit of extra attention to ensure that they properly establish themselves and actually bloom. They are rather finicky and don't adapt well to conditions that stray away from their native habitat. For this reason, it is important to follow a strict guideline as to how to grow these beautiful plants.
First, you must select healthy bulbs. If you start off your planting endeavor with less-than-decent bulbs, your chances of success are already greatly reduced. Choose bulbs that don't have soft spots. When purchasing your bulbs, be sure to find out how long they have been sitting out and if they were stored in proper conditions after being pulled from the ground. Bulbs left in unfavorable conditions deteriorate and are less likely to bloom.
After selecting your bulbs, you must find the best site to plant them. Iris plants require excellent drainage. In their natural habitat, they are used to receiving rain during the spring and fall months but remaining relatively dry during the summer. This is a rarity among flowering plants, as summer time is generally the period where flowers require more frequent waterings due to the arid environments. Because of this unique characteristic, plant placement is extremely important. You mustn't plant your bulbs near annual flowers that require frequent waterings throughout the week. Simply from being within close proximity, your iris will absorb this water, most likely rotting its roots and causing it die prematurely. Plant in areas that will remain fairly dry. Iris plants can survive the dampness of spring and fall but it will be adversely affected by excessive water throughout the summer.
Be sure to plant in soil that does not retain moisture at all, such as clay or sandy soils. Therefore, it must be a type of soil that provides excellent drainage as well as ventilation to allow the roots to breathe. Iris plants can grow well in gravel areas, such as along a driveway or near a patio. As long as it is an area where it will not be exposed to standing water or consistently wet, the plant should grow well.
When actually planting Iris bulbs, be careful not to plant them too deep, as this will inhibit their growth and may either delay or prevent their blooming. Only plant them 2 inches deep. Iris bulbs are also unique because they require slight exposure when planted. The top of the bulb should be slightly exposed to sunlight while the bottom of the bulb is buried beneath the soil where it can develop and extend its root system. However, if you live in an extremely hot and arid environment, you may want to cover the top of the bulb with a very small layer of soil. This will protect it from the harshest rays of sun, preventing it from drying out before it has a chance to grow.
You should also plan to give your Iris plenty of room to grow. It is recommended that these plants have at least 12 to 24 inches of breathing room. Although it may seem a bit excessive, if the roots of the plants begin to intertwine, it could be detrimental to your plant, voiding all of the hard work it took to cultivate it. Ample space will also reduce the number of times you have to thin your plants, creating less work in the long run.
After planting and loosely filling in with soil around the bulb, water thoroughly; it requires this initial watering to jumpstart the development process. Without watering, the soil will not settle and the bulb will not have the necessary water or nutrients to begin growing. Wet soil allows for better extraction of nutrients, stimulating growth and ensuring a healthy plant come late spring.
Once your plants have become established, the general rule of thumb is that thorough, less frequent waterings are better than frequent, shallow waterings. This means, if you live in an arid environment and it is necessary to water your plants in the summer or if they aren't receiving enough rainfall during the spring and fall months, give them a thorough drenching every two weeks or so. The frequency will vary with the intensity of the heat.
Iris plants are a great way to bring a bit of unique color to your garden, as they are an oddly-shaped flower, but gorgeous in their own right. It is lucky for them that they are such a desirable looking plant because it makes all the added steps needed to grow them much more bearable.