Planting summer flowering bulbs at the right time is key to having a bright, colorful garden when the warm months arrive. These bulbs give us blooms that make our gardens look lively and inviting. But if you plant them too early or too late, they might not grow well—or worse, not bloom at all.
This guide will walk you through everything you need to know about when and how to plant summer flowering bulbs. We will cover the best planting months, tips based on climate zones, soil preparation, and bulb care. Whether you’re new to gardening or looking to improve your bulb planting success, this article will help you enjoy a beautiful summer garden.
What Are Summer Flowering Bulbs?
Summer flowering bulbs are planted in spring and bloom during the warmer months. These bulbs love the heat and do best in warm, well-drained soil.
Common Summer Bulbs
Some popular summer flowering bulbs include:
- Dahlias
- Gladiolus
- Lilies
- Caladiums
- Canna lilies
- Tuberous begonias
- Calla lilies
- Elephant ears (Colocasia and Alocasia)
These plants bring dramatic color, unique textures, and bold shapes to garden beds, borders, containers, and even indoor pots.
Why Timing Matters for Summer Bulbs
Bulbs are sensitive to temperature. Planting too early exposes them to frost. Planting too late might shorten their blooming period. You need to plant summer bulbs after the last frost but early enough to give them time to grow roots before the heat of summer arrives.
1. Best Time of Year to Plant Summer Bulbs
After the Last Frost Date
The general rule is to plant summer flowering bulbs after the danger of frost has passed. This typically means:
- March to May in most areas, depending on your location
- Soil temperature should be consistently above 55°F (13°C)
You can find your area’s average last frost date through local garden centers or websites like the USDA Plant Hardiness Zone Map.
Timing by Hardiness Zones
| USDA Zone | Average Last Frost | Best Time to Plant |
|---|---|---|
| Zone 3-4 | Late May – Early June | Early to mid-June |
| Zone 5-6 | Mid-April – Early May | Late April to mid-May |
| Zone 7-8 | Late March – Early April | Early to mid-April |
| Zone 9-10 | Early March or No Frost | March to early April |
If you live in a colder climate, you can start bulbs indoors to give them a head start.
2. Choosing the Right Bulbs
Choose healthy bulbs. They should be firm, not mushy or moldy. Bigger bulbs usually produce bigger blooms.
Tips for Choosing
- Look for bulbs that feel heavy for their size.
- Avoid bulbs with soft spots or visible mold.
- Check packaging dates if buying from stores.
You can also buy pre-sprouted bulbs or tubers from nurseries to shorten the growing time.
3. Preparing the Soil
Bulbs need well-draining soil. If your soil is heavy clay, the bulbs may rot. Prepare your garden bed by loosening the soil and adding organic matter.
Steps to Prepare Soil
- Choose a sunny spot – most summer bulbs love full sun.
- Dig down 8-12 inches to loosen the soil.
- Mix in compost or aged manure for nutrients.
- Check drainage – if water pools, mix in sand or plant in raised beds.
- Bulbs like fertile but not overly rich soil. Too much nitrogen may cause more leaves and fewer flowers.
4. How Deep to Plant Summer Bulbs
The planting depth depends on the type and size of the bulb. A common rule is to plant bulbs 2-3 times deeper than the bulb’s height.
| Bulb Type | Depth to Plant | Spacing |
|---|---|---|
| Dahlias | 4-6 inches | 12-18 inches |
| Gladiolus | 4 inches | 6 inches |
| Lilies | 6 inches | 8-12 inches |
| Caladiums | 1-2 inches | 6-8 inches |
| Canna lilies | 4-6 inches | 12-18 inches |
| Elephant ears | 4 inches | 12-24 inches |
Always plant with the pointed end or growing eye facing up.
5. Watering After Planting
After planting, water deeply. This helps settle the soil around the bulb and encourages root growth. Keep the soil moist but not soggy. Overwatering can cause the bulbs to rot before they sprout.
Tips for Watering
- Water lightly every few days if there’s no rain.
- Once growth starts, water weekly depending on the weather.
- Mulch helps hold moisture and suppress weeds.
6. Starting Bulbs Indoors
If your growing season is short, you can start bulbs in containers indoors 4-6 weeks before the last frost.
Steps to Start Indoors
- Fill pots with well-draining potting mix.
- Plant bulbs at the same depth as in garden beds.
- Keep pots in a warm, sunny window or under grow lights.
- Water lightly until green shoots appear.
When the weather warms up, harden them off by moving the pots outdoors for a few hours each day before planting them outside.
7. Growing Summer Bulbs in Containers
Many summer bulbs grow beautifully in pots. This is a great option if you have limited space or poor garden soil.
Tips for Container Growing
- Choose containers with drainage holes.
- Use lightweight potting mix with added perlite.
- Place in sunny spots—at least 6 hours of direct sun.
- Feed every 2-3 weeks with liquid fertilizer.
- Move pots to protected areas in heavy rain or wind.
8. Common Mistakes to Avoid
Planting Too Early
Bulbs planted before soil warms up may rot or fail to grow.
Ignoring Soil Quality
Poor drainage is a leading cause of bulb failure. Always amend clay soil.
Overwatering
Bulbs rot in wet soil. Water only when the top few inches feel dry.
Not Labeling Bulbs
Use markers or garden maps. It’s easy to forget what you planted where.
9. Aftercare and Maintenance
Once bulbs sprout, you should feed them, remove faded flowers, and keep them healthy through the growing season.
Feeding
Use a balanced fertilizer (10-10-10) once shoots appear.
Fertilize again mid-season for repeat bloomers like dahlias.
Deadheading
Remove faded blooms to encourage more flowers and prevent seed formation.
Staking
Tall flowers like gladiolus or dahlias may need support to stay upright.
10. Lifting and Storing Bulbs After Season
Some summer bulbs are not frost-hardy. If you live in a cold climate, dig them up before the first frost.
How to Lift and Store Bulbs
- Gently dig up bulbs after leaves yellow.
- Shake off soil, let them dry in a shaded, airy place.
- Store in peat moss or sawdust in a cool, dark place.
- Keep storage temperatures between 40-50°F (4-10°C).
- This method applies to dahlias, caladiums, elephant ears, and others not hardy in your zone.
11. Summer Bulbs That Return Year After Year
Some summer flowering bulbs are perennials in warmer zones and don’t need to be dug up.
Hardy Summer Bulbs by Zone
- Lilies – Hardy in Zones 3-9
- Daylilies – Hardy in Zones 3-10
- Gladiolus (some types) – Hardy in Zones 8-10
- Canna lilies – Hardy in Zones 8-11
In colder zones, treat these as annuals or lift and store them.
12. Companion Planting Ideas
Summer bulbs can be planted with other flowers and greenery for a full, colorful garden.
Good Companions
- Dahlias + Zinnias – Bright color all summer.
- Lilies + Hostas – Textural contrast.
- Gladiolus + Snapdragons – Height and variety.
- Caladiums + Ferns – Shade lovers with texture.
- Canna lilies + Ornamental Grasses – Tropical vibe.
Grouping bulbs with other plants helps hide fading foliage after flowering too.
Frequently Asked Questions
Can I plant summer bulbs in fall?
No. Summer flowering bulbs need warm soil and should be planted in spring. Fall is the time to plant spring-flowering bulbs like tulips or daffodils.
Do I need to fertilize bulbs right after planting?
No. Wait until green shoots appear before applying fertilizer. Too much early fertilizer may burn new roots.
What if I plant too late in the season?
Bulbs planted late may still grow but will bloom later or be smaller. If it’s too late in your area, try starting them indoors next season.
Conclusion
The best time to plant summer flowering bulbs is after the last frost, when the soil has warmed. Understanding your zone, choosing healthy bulbs, and preparing your soil can make a big difference. These bright, bold plants bring joy all summer long when planted with care. Follow the timing and tips in this guide, and you’ll enjoy a colorful, blooming garden that lasts through the warm months.
