Bulb Planting: What, why, when & how…
What are bulbs?
Bulbs have a variety of root structures and understanding them is important when it comes to both planting as well as maintaining them during the season and through the winter.
True Bulbs: These consist of a basal plate from which roots grow and fleshy scales that store nutrients. Examples include tulips, daffodils, and lilies.
Corms: Solid, swollen stems that store nutrients. Unlike true bulbs, corms are not layered but have a solid, bulb-like structure. Examples are crocuses and gladiolus.
Tubers: Swollen underground stems with a solid center. They serve as a storage organ for nutrients. Examples include tuberous begonias.
Rhizomes: Horizontal underground stems that store nutrients and propagate new growth. Examples are irises and canna lilies.
Choosing Bulbs
Quality: Select bulbs that are firm and plump. Avoid bulbs that are soft, moldy, or damaged.
Variety: Choose varieties that suit your climate and soil conditions. Some bulbs are better for cooler climates, while others thrive in warmer regions.
Purpose: Consider the purpose of your planting. Some bulbs are excellent for naturalizing (returning year after year), while others are better suited for creating annual or biennial displays.
Timing for Planting Bulbs
Timing is crucial for the successful growth of bulbs. Different bulbs have different planting seasons.
Fall Planting
Most bulbs, including tulips, daffodils, and hyacinths, are planted in the fall, about 6-8 weeks before the ground freezes. Planting in fall allows bulbs to establish roots before the winter, which helps them bloom earlier in the spring. If you wait until spring to plant, you’ll not only battle storing the bulbs through winter, but you may have delayed displays of your anticipated blooms.
Spring Planting
Bulbs such as lilies, begonias, and dahlias are typically planted in the spring after the danger of frost has passed. Spring planting gives these bulbs the best chance to grow and bloom before the summer heat sets in. These frost-sensitive bulbs should be dug up and properly stored through the winter for subsequent spring plantings.
Site Selection and Preparation
Choosing the right location and preparing the soil is essential for bulb health and growth.
Sunlight Requirements
Full Sun: Most bulbs need at least 6 hours of direct sunlight per day. Ensure your chosen site receives adequate light.
Partial Shade: Some bulbs, such as snowdrops and aconites, can tolerate or even thrive in partial shade.
Soil Conditions
Drainage: Good drainage is crucial to prevent bulb rot. Test your soil; it should drain quickly after a heavy rain.
Soil Type: Amend heavy clay soils with organic matter like compost to improve drainage. Sandy soils may require additional organic matter to retain moisture.
Soil Preparation
Testing Soil pH: Bulbs generally prefer slightly acidic to neutral soil (pH 6.0-7.0). Test your soil and amend it if necessary.
Loosening Soil: Dig and loosen soil to a depth of 12-15 inches. Mix in compost or well-rotted manure to enrich the soil.
Planting Bulbs
Depth and Spacing
Depth: Plant bulbs at a depth of 2-3 times their height. For example, a 2-inch bulb should be planted 4-6 inches deep.
Spacing: Space bulbs based on their type:
Small Bulbs: 2-4 inches apart.
Medium Bulbs: 4-6 inches apart.
Large Bulbs: 6-12 inches apart.
Note that most packaging of purchased bulbs will give specific planting directions for the variety selected.
Planting Steps
Digging Holes: Use a trowel or bulb planter to dig holes to the appropriate depth.
Adding Fertilizer: Spread compost both in and around your planting hole. This provides essential nutrients for growth. Alternatively, mix an organic bulb fertilizer into the soil at the bottom of the hole
Placing Bulbs: Position bulbs with the pointed end facing up. Place bulbs with the flat, root end down.
Covering: Fill the hole with soil and gently tamp down to eliminate air pockets. Ensure the bulb is well-covered.
Watering: Water the area thoroughly after planting. This helps settle the soil and initiates root growth.
Care and Maintenance
Watering
Water thoroughly after planting. Be sure not to water when ground is frozen! Spring showers will likely keep your bulbs watered adequately for spring blooms!
Mulching
Mulch helps retain soil moisture, suppresses weeds, and maintains a stable soil temperature. Use shredded leaves, bark, or straw as mulch. Apply a 2-3 inch layer over the planted area.
Fertilizing
Timing: Apply a balanced fertilizer in early spring as shoots emerge. Follow the manufacturer’s instructions for application rates.
Type: Use a fertilizer specifically formulated for bulbs, which often includes a higher phosphorus content to promote flowering.
Pest and Disease Control
Pests: Watch for pests like aphids and bulb mites. Address infestations with appropriate treatments, such as insecticidal soap or neem oil.
Diseases: Avoid common bulb diseases by ensuring good drainage and proper spacing. Remove and discard any diseased bulbs.
Troubleshooting Common Issues
Addressing issues promptly can prevent problems from worsening.
Bulbs Not Blooming
Possible Causes: Incorrect planting depth, insufficient sunlight, or poor soil conditions.
Solutions: Ensure bulbs are planted at the correct depth, receive adequate sunlight, and have well-drained soil.
Rotting Bulbs
Possible Causes: Overwatering or poorly-drained soil.
Solutions: Improve drainage by amending soil and reducing watering. Avoid planting in areas prone to standing water.
Critters!
Symptoms: Snowdrops, crocuses and tulips are delicious treats for hungry rabbits, moles and voles.
Solutions: Plant more daffodils! You can also bury a hardware cloth barrier around your bulbs with the edges extending 12-16” above the soil to create a barrier as the bulbs first pop.
Replanting and Dividing Bulbs
As bulbs grow, they may need to be divided or replanted to maintain healthy growth.
Replanting
Timing: Replant bulbs in the fall or spring, depending on the type. Fall-planted bulbs should be handled after they have gone dormant.
Procedure: Dig up bulbs carefully, separate any that have become crowded, and replant them in fresh soil.
Dividing Bulbs
When to Divide: Bulbs that have become overcrowded or have decreased in bloom quality should be divided. If you have too many, bulbs can make a great fall equinox gift to share the beauty come spring!
Method: Gently dig up bulbs, separate them into individual bulbs or clusters, and replant in well-prepared soil.