Irises bloom for a short period of time in early summer, then the leaves remain until fall to collect nutrients for next years blooming. Irises require minimal maintenance, making them a favorite in many home gardens. Some of this maintenance takes place in fall to prepare the plants for winter. Winterize iris once the foliage begins to brown and die back in mid to late autumn. This prevents iris borers from killing the rhizomes as well as improving the look of your garden over winter.
Stop watering the iris after the last blooms fade in early summer, or late summer for double blooming varieties. Natural rainfall and moisture is all that is needed at this time.
Let the foliage yellow and die down naturally. Avoid removing any of the foliage until it is completely died back or until the first light frost in autumn—whichever occurs first.
Cut off all dead leaves with gardening shears 1 inch above the soil surface or rhizome, if it is visible. Leave the small ring of new, green leaves at the base of the plant in place, as they collect nutrients over winter.
Inspect the new leaves for dark brown streaks, as this is a sign that iris borers have laid eggs on them. Remove any affected leaves but allow the healthy ones to stay on the plant.
Cut off any remaining flower stalks in the center of the plant. Remove them at the base of the plant.
Remove leaves, grass and other garden debris from the base of the plant. Brush away any soil covering the rhizomes so they are just visible at the soil surface.
Inspect the visible rhizomes tops for signs of rot such as softness or bruised spots. Remove any damaged or rotted rhizomes so they don't spread infection to the healthy ones.
Things You Will Need
- If your iris needs divided, do so in late summer. Cut the foliage down to 6 inches prior to dividing, but don't remove completely until it's time to winterize.
- Do not apply mulch over iris beds in winter. This leads to moisture retention and causes the rhizomes to rot.