Many bulbs, including those that are shallowly planted, seem to tolerate soil temperature fluctuations, though outright freezing and thawing cycles may dislodge them from the soil and break their roots. But it’s still a good idea to protect your plantings with mulch that helps regulate the surface soil temperature, retains moisture and hinders the germination of weed seeds. Mulch has a neat appearance and helps keep the cultivated soil’s surface open so that it absorbs water without runoff.
Mulch helps insulate the soil, prevents freeze-thaw cycles and holds soil moisture. Dry pine needles make a good mulch because they protect the bulbs and add nutrients and acidity to the soil as they slowly decay.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
By spring, the needles will start to emerge from the melting snow.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
When selecting mulch, opt for organics rather than rock, plastic or sand. Mulches made of plant matter decompose slowly, improving the soil texture and releasing nutrients. As organic mulches break down, soil bacteria first absorb nitrogen and oxygen, robbing shallow-rooted weeds of nutrition without affecting the deeply rooted bulbs. Later, they release the mulch’s nutrients and fertilize your beds.
Soil is a good insulator – temperatures at shallow depths frequently remain constant unless cold air is accompanied by chilling rain, and because many bulbs are planted deeply, they’re protected from sudden frosts. Mulch adds even more insulation, further reducing temperature fluctuation. Shredded bark and leaves, wood chips, organic compost, ground cocoa and rice hulls, and weed-free straw are good choices. Avoid using sphagnum and peat as a mulch for your bulbs – water tends to run off these them without being absorbed, plus, the rare natural bogs in which they form are threatened by depletion and overharvest.
Apply mulch in a 1- to 2-inch thick layer after planting your bulbs. Sprouting bulbs will push through the mulch as they grow. For summer bulbs like gladiolus and lilies, rake the mulch away from their stems once their foliage has emerged to avoid creating too-moist conditions and harboring fungal spores that could promote disease on their stems. A clear circle 2 inches in diameter is usually sufficient.
Where bulbs will overwinter in your garden, apply mulch heavily in autumn to extend its insulating benefits, naturally fertilize your soil and dress up your fall landscape. Mulch also helps to protect the soil from freeze-thaw cycles that sometimes can uproot bulbs.
Mulching around bulbs that have already sprouted is easy: Just take the simple steps shown in the following pictures and described in their captions. (Use a garden cart to carry the mulch over to your planting site and a mulching rake to spread the material.)
Mulching Around Bulbs - Step 1
Begin by dumping cartloads of mulch at several points within the flower bed. The contents of a full 5-cubic-foot cart or wheelbarrow will cover a 15- to 20-square-foot area.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Mulching Around Bulbs - Step 2
Use a mulching rake with long tines to spread the mulch over the bed surface in an even layer, about 1-2 inches thick.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
Mulching Around Bulbs - Step 3
If your bed includes trees, shrubs or perennial plants as well, and you live in a humid climate, keep mulch 4-6 inches from their trunks or stems.
Photo Credit: ©2002 Dolezal Publishing/John M. Rickard
