•Work while the weather is pleasant
Those of us who have seen a few more winters appreciate warmer soil under the knees or the opportunity to spread chores out over a longer period of time. On the home farm, we do not generally have enough time to clean the garden until after our fall bulb harvest and shipment is completed in early November, but we do start by cutting back any lily stem that has completely browned by early September. When the lily leaves have turned from green to at least yellow-green over most of the stem, you can safely cut them back to just above ground level. Do not pull stems out of bulbs as you risk doing serious damage to the bulb. Until stems are fully brown and crispy, there is enough moisture in stems to tear tissues within bulb centers, opening up the possibility of rot over winter.
• Reduce the possibility of spreading fungus spores
Some areas have been very wet and cool this spring and summer and the pesky fungus Botrytis has been a concern for more than one gardener this year. Any stems/leaves/flowers that show tell tale brown spots should not be added to the compost, but rather sent to the trash. Fungus spores typically are not damaged by the low heat of compost piles and could still be active should you spread the finished product in your garden. These spores do not "contaminate the soil", but rather tend to live on the surface over winter, so it is a good idea to clean leaves from not only lilies, but also roses and peonies at summer’s end.
• Removal of spent blooms helps bulbs to grow larger next season
In commercial production, the bulbs are planted in long rows. The last 3 feet of each variety is allowed to open flowers for photos and to check the planting stake is correct and then the flowers are removed to encourage the largest growth possible for the season. Everything a lily bulb needs for flowering in a given year is already present, and as the stem elongates, the scales that make up a bulb are slowly depleted. Once flowering is completed, your lily begins the task of rebuilding itself for next year’s growth, the reason why you do not want to allow seed pods to develop (which saps strength) or cut off too many green leaves needed for photosynthesis.
• Freshens the appearance of your garden
Simply removing faded flowers once a week can lift spirits and improve the look of your garden with very little time or effort. Cutting off the top of each stem, leaving all leaves below where the bottom flowers helps to camouflage maturing stems very neatly and directs attention to other shrubs and perennials nearby. Again, when the lily leaves have lost their green color, you can safely cut them back to the ground to begin preparing your garden for winter. The stem in the clump of lilies to the right is just beginning to mature; only the top portion has turned from green to yellow. If you wish, clipping back the yellowed section for neatness will not compromise the bulbs' ability to continue to manufacture food.