It is time to say goodnight to perennializing spring bulbs here at Wellfield. As you know from reading this blog, we treat our tulips as annual bulbs and remove them every spring. But the daffodil bulbs stay in the ground to delight us again next year. A question we get a lot is, how long should we leave those leaves on? Glad you asked. One of the projects we have going now is cutting back the large number of daffodil bulbs in the Spring and Conversation Gardens.
Bulbs are modified leaves some plants utilize to store excess sugars. Species like Narcissus (daffodil), Scilla (squill) and Hyacinthus (garden hyacinth) naturally grow in conditions where early spring flowering is most favorable. Once the plant exhausts last year’s energy stores to produce leaves and flower, it needs time to recoup and store for next year. Just as cool season turf grasses like Kentucky bluegrass go dormant brown in the hot, dry mid-summer, these species go dormant to preserve their gains until next spring’s favorable conditions return. It is for this reason horticulturists recommend leaving perennial bulbs of any sort, including summer species like asiatic lilies, until the leaves senesce (turn brown and wither).
There are a couple of different ways one can deal with spring bulb leaves. The first and ideal method, in many respects, is to leave them to compost in place as long as there are no foliar disease issues present, which are a rare occurrence. The rotting leaves add much needed organic matter and nutrient cycling to the garden plot. One can interplant these species with later blooming material, such as daylilies, which grow up to hide the “unsightly” bulb leaves. In this photo, one can see the daffodil leaves dying back under daylily leaves.
Where this is not an option, one should cut the leaves back to the ground, gather and compost.
Horticulture and Facilities Manager, Wellfield Botanic Gardens