Bulbs to Plant in May

Flowering Bulbs in May

May is prime planting time. The soil is warm, the risk of frost is low, and summer flowering bulbs planted now will establish quickly and bloom through the heart of the season. Whether you're filling containers, topping up borders, or planting up a sheltered spot, there's still plenty of time to get great colour in the ground.

Quick wins in May:

• Ideal for borders, pots, and containers where you want late summer impact
• Perfect for dahlia tubers, tiger flower, and other bulbs that need warm soil to thrive
• A great opportunity to fill any gaps left after spring bulbs have finished

What Bulbs Can You Plant in May?

May suits a good range of summer bulbs, corms, and tubers that prefer warmer conditions to get going. The soil is consistently warmer than in April, which means faster root development and stronger growth from the start.

In May, look out for bulbs that:

• Are listed as ready to plant now (check each product page)
• Thrive in full sun or tolerate partial shade depending on your garden
• Prefer well drained soil enriched with a little organic matter
• Suit containers or potted bulbs if your borders are already full

Top 5 Bulbs for May Planting

1. Dahlia tubers: Still a fantastic choice in May. Plant in a sunny site with good drainage and you'll have bold, generous blooms from midsummer through to the first frost. Great as cut flowers too.
2. Tigridia (Tiger Flower): A striking and slightly underrated bulb that deserves more garden space. Plant in full sun with well drained soil and it'll produce vivid, exotic-looking blooms through early summer and beyond.
3. Eucomis (Pineapple Lily): One of the best bulbs for late summer interest. Give it a warm, sheltered spot in full sun and it'll reward you with its distinctive flower spikes when many other bulbs are winding down.
4. Gladiolus corms: Tall, elegant, and brilliant for cut flowers. May planting gives corms plenty of time to establish before they bloom, and staggering your planting time across a few weeks will extend the flowering season nicely.
5. Calla Lilies: Elegant and versatile, calla lilies suit both pots and borders. They prefer moist, well drained soil and do well in full sun or partial shade, making them a reliable choice for most gardens.

Planting Tips for May Bulbs

The warmer conditions in May make planting straightforward, but a few basics still apply.

Soil preparation matters: Work in some organic matter before planting to improve structure and moisture retention, especially in sandy or free-draining ground.

Good drainage is essential: Most bulbs will rot in waterlogged conditions. If your soil holds water, plant in raised beds or containers with drainage holes.

Choose the right position: Most hardy bulbs prefer a sunny site, but some, like calla lilies, will tolerate partial shade. Match each variety to the right spot for the best results.

Depth and orientation: As a general rule, plant at 2-3x the height of the bulb, with growth points facing upwards. Check individual product guidance for anything specific.

Avoid planting during a late cold snap: May frosts are rare but not unheard of. If cold nights are forecast, hold off a few days or start bulbs off in pots you can move under cover.

Aftercare Made Simple

May-planted bulbs establish quickly in warm soil, so aftercare is mostly about keeping conditions consistent. Water well after planting, then keep the soil just evenly moist. Pots and containers will need more regular attention than border plantings.

Once growth is active, a light feed will help. Deadhead spent flowers regularly to encourage more blooms and keep displays looking their best through late summer. As the season winds down, let foliage die back naturally so bulbs can store energy for the following year. Tender varieties like dahlias should be lifted before the ground freezes in autumn and stored somewhere frost-free until the following spring.

Frequently Asked Questions

Can I still plant summer flowering bulbs in May? 

Yes, May is actually one of the best months for planting summer bulbs. The soil is warm and conditions are ideal for quick establishment.

Is May too late to plant tulip bulbs or other spring flowering bulbs? 

Generally, yes. Tulip bulbs and most spring flowering bulbs are best planted in autumn for a spring display. By May, planting bulbs like these is unlikely to give good results. Focus instead on summer bulbs that are suited to a May planting time.

What's the difference between planting in pots versus the ground in May? 

Both work well in May. Potted bulbs tend to establish a little faster as containers warm up more quickly than garden soil, and they give you flexibility to move plants around. Borders are great for hardy bulbs that will naturalise and come back year after year.

Will iris bulbs planted in May flower this year? 

It depends on the variety. Some iris bulbs can be planted in spring for summer blooms, but most prefer an autumn planting for the best display. Check the individual product guidance, as planting time varies quite a bit across iris types.