Is there “any” spring flowering bulb that will do well planted underneath an evergreen tree in zone 5?
Anything, whether a bulb, perennial or shrub that you may want to plant under an evergreen tree will need several qualities to grow well: drought tolerance, shade tolerance and tolerance for acidic soil. Even so, many sites do not recommend bulbs as an underplanting for evergreens. Early flowering bulbs when planted under deciduous trees (those that lose leaves each fall) get enough light as the leaves haven’t sprouted yet.
I am guessing that we are talking about a single specimen with sweeping branches that reach the ground and provide quite dense shade. Unless the tree is pruned or ‘limbed’ up to allow more light to hit the ground, only shade-loving plants will do well enough to grow under them. The dropped needles from evergreen conifers may lower the pH level of the soil as they break down, and the tree roots take up most of the available water.
So, with all that in mind, the following will help with maintaining the bulbs planted under the tree:
If possible, prune up the sweeping branches to allow more light under the tree.
Although tree roots tend to take over an area, which makes digging holes a challenge, try to find areas that a hole of suitable size can be dug and organic matter, such as compost can be added for the bulbs. This will help keeping some moisture in the area of the bulb.
Plant early flowering specimens as they will do better than late flowering specimens.
Bulbs should be planted in a random pattern, in uneven groups of no less than 5 bulbs, to a depth recommended for each bulb.
Keep them watered for the first few years, to become established.
Finally, some shade tolerant bulbs that will grow under the evergreen can include:
lily-of-the- valley (Convallaria majalis) – quickly spreading, early white nodding, bell shaped flowers, highly scented
winter aconite (Eranthus hymalis) – very early, short plant, yellow flowers, will even grow on paths
snow drops (Galanthus nivalis) – very early, white flowers, spreads in more ideal conditions
scilla (Scilla siberica) – early, naturalizes easily, blue flowers in clusters, low humus soils
species tulips (Tulipa tarda, T. urumiensis, T. turkestanica, T. pulchella var. humilis) – early to very early, small, tulip shaped flowers, drought tolerant
All of these do well in my garden, which is tree covered (not evergreens) and is generally very dry sandy soil.