Why is it that the perfect time to dig and divide your iris bed is in July at the height of the season’s heat?
For bearded iris, it’s because they go through a dormant period in the summer.
This hardy perennial is a beautiful spring bloomer that is virtually immune to diseases. But to ensure health and vigor, you should divide your bearded iris every three to five years.
If they receive adequate sunlight (at least six hours a day), but do not bloom well, then it is definitely time to divide.
If you have not had rain for a while you may want to soak your iris bed the day before to make it easier to work.
Take your spade or pitch fork and lift the iris rhizomes (roots) off the top of the soil where they grow.
Cut away and discard the older rhizomes and save the lighter-colored young rhizomes that are growing off their sides.
Cut the fans back to about two to three inches in height and replant them in a sunny location in groups of three to five fans.
Arrange the grouping with the fans towards the center so that as they multiply the grouping will multiply outward in a circle.
Daddy had a good description about how they should be planted, like “ducks on water” he would tell me.
The rhizome should not be completely buried, leave half of it above the soil level.
As you divide your iris, examine the rhizomes for any holes that may be trailing through them.
Bearded irises are immune to fungal diseases but they can be plagued by the iris borer. The holes are a telltale sign of borers.
This big, black-headed, pink grub is the larval stage of a brown or black moth. The moth lays its eggs on the iris foliage starting in the summer and continuing into fall.
Next spring, the pink grubs will appear and chew their way into the foliage, down through the stems and into the rhizome.
The grubs feed on the rhizome until they hatch into moths and the cycle begins again.
In the spring, inspect your irises and if there appears to be something feeding on the foliage run your fingers along the blade, applying slight pressure. If the grub is there you have hopefully crushed it.
This is the best time to control the borer because once it has reached the rhizome there is little you can do.
Another rhizome that should be divided now is the daylily.
Daylilies are also an incredibly hardy perennial and can be divided every three to five years to ensure maximum blooming.
Mites and aphids can infest daylilies, though they rarely kill them.
Watch for webbing, white insects at the base of the plant, or deformed leaves or buds.
Insecticidal soaps will control these insects if the pressure if significant.
To dig daylilies, take a spade or pitch fork and work the strong rhizomes out of the soil.
Once you have removed the root ball, take your spade and “cut” through the root system.
Don’t be afraid to be assertive, you won’t hurt the plant. Daylilies will grow anywhere, but to encourage better growth, work some compost into the new hole, mound up the center and place the division on top.
Work the fleshy roots of the rhizome over the mound and cover with soil up to where the foliage meets the root system.
After replanting your newly divided plants, water well to settle the soil around the roots and irrigate once a week if Mother Nature does not deliver on the precipitation.