Your Guide to Growing Summer Bulbs

A bright, blooming border of dazzling flowers always stops us in our tracks. Giant heads of dinnerplate dahlias seem to defy gravity. Tropical-looking clusters of towering gladiolus dance with fragrant lilies and summer perennials. Gardens like this seem totally unattainable… an Instagram dream only achieved by the seasoned pros. This isn’t true! The summer-flowering bulbs, tubers, and corms that are arriving in garden centres now contain the secret potential of the swoon-worthy flowerbed! Don’t be intimidated, with a bit of advice, you can do this! Here is your guide to growing summer “bulbs”, like dahlias, gladiolus, ranunculus, and lilies.

What Are Summer “Bulbs”?

Good question! What are often referred to as “summer bulbs” or “spring-planted bulbs” are a collection of dormant bulbs, tubers, and corms that are planted in the spring, and bloom in the summer. Some, like dahlias, ranunculus and gladiolus, aren’t hardy to Ontario winters. These need to be lifted from the garden in Fall, stored indoors for the winter, and replanted in the garden in spring. Others, like Lilies, can stay in the garden year-round. These will establish in the garden, and will often multiply over time. The time to start the dream of that summer garden is now – dormant summer bulbs have arrived in stores, and the best selection sells out quickly. Shopping for summer flowers with snow on the ground is a task of joy and excitement for the season ahead. It’s the perfect way to start making plans for what your 2022 garden will become!

The Deal With Dahlias

It’s no overstatement to say that Dahlias are the crown jewels of any flower garden. These bloom-filled plants are unlike any other garden flower. A dahlia tuber looks like a misshapen potato. Yet somehow, when you plant it in the spring garden, it grows to become an impressive bush, topped with huge flowers that bloom from summer until they’re covered in frost. They’re the highlight of any cut flower garden, and they keep flowering more bountifully the more you harvest them. Dahlias are flower magic! In exchange, they do ask for a bit of extra attention – you have to dig and store them in the Fall (you can learn how to do that here) or you can simply enjoy them for the season, knowing that they won’t make it through the winter.

How to Grow Dahlias:

Plant tubers in spring, after risk of frost has passed. Dahlias need full sun, and prefer a soil that’s amended with organic matter, like compost. Plants get big and need support, so hammer a stake into the ground when planting to tie to as it grows. Blooms will begin in midsummer and continue through Fall. Feed with a blooming plant food every 3-4 weeks for best flowers. After frost has killed the top growth in Fall, dig up tubers and store for the winter. Tubers multiply into a clump throughout the growing season. You’ll find you have more dahlias to plant next year!

Gladiolus (or ‘Glads’ if you’re a gardener)

Gladioli are fabulously showy, with dramatic spikes of colourful blooms. These plants are related to irises, and would be perennial if our winters were milder. In chilly Ontario, their disc-like corms get planted after last frost in the spring. Gladiolus corms need to be lifted and stored in the winter, like Dahlia tubers. Glads bloom in a riot of colour in summer, and are available in a huge range of colours. Flowers can be huge and frilly, or small and delicate, depending on the variety, and they vary in height from 2 to 5 feet tall. Have you been tempted by large bouquets of gladiolus at the farmer’s market? Now you can grow your own and discover the joy of fresh flowers from your own garden!

How to Grow Gladiolus:

Plant in the garden after risk of frost has passed. Glads want a full sun location, and look wonderful in a border garden. Mix them in drifts through the middle or back of the bed, depending on the height of the varieties you choose. These plants prefer a well-drained soil. It’s best to avoid planting in heavy clay to prevent corms from rotting. Glads begin blooming 2-3 months after planting. If you’re ready for an advanced move, try planting some corms in successions, every 3 weeks or so. This way, the blooms will continue all summer and into Fall! Corms need to be dug up for storage after the first Fall frost.

Ranunculus (hard to say, easier to grow)

Ranunculus (or Persian Buttercup, or ‘Nuncs, if you’re a cool kid) are the darlings of the late spring season. They’ve definitely gained a new level of popularity in recent years, and make an impressive addition to spring planters and garden beds. A dormant Ranunculus corm looks like tiny, dried out octopus… you’d never suspect that it would produce such a gorgeous flower! Ranunculus prefer cooler temperatures, and their season in the garden is short and sweet. Grow them in places where you can enjoy them up close, like along pathways, in planters or bowls, or as cut flowers for outstanding bouquets.

How to Grow Ranunculus:

The only tough thing about growing Ranunculus is accepting that they’re not going to stay for very long. Incredible beauty like this is fleeting. The ‘Nuncs begin to go dormant once the heat of summer arrives in late June, so planting them as early as possible will give you the longest bloom time. For maximum season length, try pre-sprouting Ranunculus corms in late March! Soak the corms for a few hours, and plant into a tray of seed starting mix. Place them into a sunny window or under a grow light, and the plants will root, sprout and begin to grow leaves. Sprouted plants can be planted out into well-drained soil in the garden in late April, and will bloom from May through June.

Lots of Lilies

Canna lilies, Calla Lilies, Asiatic and Oriental Lilies are all popular choices for Spring planting. Canna Lilies are a spectacle in summer containers and garden beds, with giant, tropical leaves and fruit-punch coloured flowers. Calla Lilies are ideal in smaller pots on tabletops, and can even be used along edges of ponds. These bulbs, like those above, need to be stored indoors for winter. Alternately, Asiatic and Oriental lilies can be planted as hardy perennials, and will create a larger clump of flowers over time.

Prep for Planting

So… are you excited for Spring? Right now is the time to begin! Browse racks of summer bulbs, or pick through packets of seeds. February and March are the months to get your gear in order, so that you’re ready to start when the thaw happens. The garden of your dreams awaits!