Combining spring-flowering bulbs with herbaceous perennials is a design technique used to achieve continuous color and structural interest. Bulbs, such as tulips and daffodils, are specialized underground storage organs that provide a burst of early-season color before most other plants awaken. Perennials live for more than two years, providing the garden’s permanent structure and later-season foliage and blooms. Interplanting these types creates a dynamic display where the ephemeral beauty of the bulbs gives way seamlessly to the long-lasting presence of the perennials.
Choosing Compatible Partners
Successful co-planting requires selecting varieties with shared environmental preferences, focusing mainly on light and soil conditions. Bulbs require well-draining soil to prevent rot during their dormant summer phase, a characteristic the chosen perennial must also tolerate. This often means selecting perennials that thrive in loamy or slightly drier conditions, as heavy clay soil will cause the bulbs to fail. Matching sun exposure is equally important; shade-loving perennials like Hostas should be paired with bulbs that tolerate shade, such as certain daffodils or scilla.
A strategic consideration involves the perennial’s growth habit and emergence timing, which is important for masking the bulb’s decline. Look for perennials that emerge later in the spring or develop dense, spreading foliage to cover the fading bulb leaves. Daylilies (Hemerocallis) and Brunnera are excellent choices because their foliage begins to bulk up just as the bulb leaves start to yellow and collapse.
The Technique of Layered Planting
Planting bulbs and perennials together often employs “bulb layering” or the “lasagna method” to maximize space and extend the bloom sequence. This technique requires digging a single, large planting area deep enough to accommodate the largest bulbs. Fall is the optimal time for planting spring-flowering bulbs, allowing their roots to establish fully before the ground freezes.
Start by excavating a hole based on the largest bulb’s requirement, typically three times its height (8 to 10 inches for large tulips or daffodils). Place the largest, latest-blooming bulbs at the bottom, pointed end upward, and cover them with about two inches of soil. Next, place a layer of medium-sized bulbs, such as hyacinths or mid-season tulips, staggering their positions so they are not directly above the lower bulbs. Cover this second layer with another inch or two of soil before placing the smallest, earliest-blooming bulbs, such as crocus or muscari, closest to the surface. Finally, position the perennial root ball either directly above or slightly offset from the layered bulbs, ensuring its crown is level with the surrounding soil. This vertical arrangement allows each bulb type to sprout and flower sequentially.
Managing Seasonal Transitions
Ongoing management focuses on maintaining the health of the subterranean bulbs while keeping the garden visually appealing. The most significant maintenance point is allowing the bulb foliage to decay naturally after the flowers have faded. The green leaves must remain intact for approximately six weeks to perform photosynthesis, storing the necessary carbohydrates for the following year’s bloom.
Resist the temptation to cut back or tie up the foliage, as this severely reduces the leaf surface area available for energy production. Strategically planted perennials become invaluable here, as their rapid spring growth camouflages the untidy, yellowing bulb leaves. Perennials like Hostas or Catmint develop substantial foliage masses that effectively screen the decaying bulb material until it has fully withered and can be safely removed.
Post-bloom care involves deadheading the spent bulb flowers, which prevents the plant from diverting energy into seed production. Deadheading redirects the plant’s focus toward strengthening the bulb for the next season. Applying a low-nitrogen, high-phosphorus fertilizer, such as bone meal, around the base of emerging bulb shoots in early spring supports both the bulbs and the surrounding perennials.