Planting Bulbs Outdoors

Click here to view our bulb planting chart.

All the varieties of outdoor bulbs we offer are suitable planted outdoors somewhere in Maine. With the climate changing, Waterville has been re-assigned from USDA Zone 4 to Zone 5. Fifty miles to the west in the mountains is still Zone 3; and fifty miles east or south, along the coast, is now Zone 6 or higher. Local cold (or warm) pockets, northern slopes, hills and lakes can all affect your micro-climate, and may make the large-scale maps printed by the USDA inaccurate for your plot. Your cooperative extension service may have maps showing local zones or see the USDA’s website for a large, full color, detailed zone map. You can use rock walls and heavy mulch to shift conditions to your advantage. We have seen some Zone 7 and 8 plants thriving in south-facing protected pockets in Zone 5.

Planning and Planting

Bulbs are easy to work with, very rewarding and forgiving. They look best planted in groups or clumps, naturalized in the sod, under trees, or in beds, borders or rock garden. Good drainage is essential; bulbs will grow poorly or rot if they are too wet.

Prepare beds by mixing fertilizer, bonemeal and wood ashes, or other phosphorus and potassium sources into the soil below the level of the bulbs. Mix in compost to lighten heavy soils and increase nutrients. Peat is acidic—use with caution. Although widely available, Holland Bulb Booster contains ingredients which are not approved for organic growers.

Plant bulbs pointed side up; generally the depth of the hole is three times the bulb’s height. See our chart showing suggested planting depth and spacing. Topdress the bed with compost.

Mulch your bulbs with 4-6" of leaves, bark, straw, etc. after the ground freezes. If you plant them next to your house, it’s especially important to use the higher amount or more, as basement heat and reflected sunlight will likely remove the insulating snow cover, exposing them too early to alternating sunny days and freezing nights, and damaging their growth tips. Wherever they’re planted, bulbs need insulation. You need to mulch (or plant extra deep) unless winter will provide a consistent heavy snow cover. A good mulch can also give protection up to half a hardiness zone, enabling you to experiment with bulbs not quite hardy in your zone.

Do not remove the mulch too early in the spring. By keeping the soil from thawing, mulch prevents heaving and false starts in early warm spells, and delays flowering slightly for a more uniform and longer-lasting display. Remove mulch as the bulbs begin to peek through in the spring, and dress the bed with compost or bulb fertilizer.

Pinch the blooms as they fade to discourage seed production and to force the energy back into the bulb. This is especially important for tulips and hyacinths, which can otherwise lose their vigor in 2-3 years.

Do not cut the foliage as long as it remains green; it produces the food for the bulb’s future blooms. Cut leaves only after they yellow. Sidedress with fertilizer or compost in late summer to mid-fall.

Troubleshooting

If squirrels, chipmunks or voles are a problem, try chicken wire or sharp gravel placed in the ground surrounding the bulbs. (Blood meal also repels many critters, but it also may repel people and attract dogs, skunks or raccoons.) Or plant Narcissus, Allium, Fritillaria or Ipheion, which critters don’t generally bother.

To disrupt squirrels’ ability to “smell out” the bulbs in new plantings, we routinely dust those areas with black pepper and ground cloves right after planting in the fall and again in the spring when growth first emerges. The odor in the yard, reminiscent of chai, is a nice touch for us.

If after several years your bulbs produce leaves but not flowers, they may be suffering from overcrowding (dig in autumn, separate and replant), insufficient sun (move to new location), undernourishment (sidedress thoroughly) or marginal zone hardiness (give to a friend further south).