As gardeners rush to plant bulbs in the ground and get containers for the flowers next spring, there's one approach worth trying now: the lasagna method. The basic idea is to plant bulbs with different bloom times in a pot at different depths so you have a range of blooms throughout the spring.
“It offers maximum impact in minimal space – in pots – because you can stack the bulbs deep and in layers,” says garden designer, nursery owner and bulb expert Sarah Raven. Here's Raven's step-by-step guide to using the lasagna method and her favorite combinations for a spring full of color.
Sarah Raven is a UK-based garden designer, author and owner of the mail-order nursery sarahraven.com. Her latest book is titled A year full of pots.
Planting lasagna step by step
Planting using the lasagna method is almost as easy as potting any other bulb. The key is to plant the right bulbs at the right depth.
1. Collect materials: Choose three types of bulbs, ranging from large to small, that bloom at different times of the year. Choose a large pot with drainage holes and fill it with good quality potting soil.
2nd plant: Place several of the larger bulbs – such as alliums, tulips or daffodils – at a depth of about 30cm. Alternate a layer of soil with bulbs and plant the second largest bulbs about 20 cm deep in the center and the smallest bulbs (such as anemones, crocuses or irises) 10 cm deep. In each layer, the bulbs should be about 1 inch apart. Water well.
3. Overwintering: Flower bulbs planted in autumn require constant temperatures between 10 and 18 °C for two to three weeks in order to form sufficient roots. In USDA hardiness zones 3-5, store potted onions in an unheated garage or shed where temperatures remain cold and water them once a month to keep them from drying out.
In zones 6-8, place potted bulbs outside in a shady location. Keeping them in the shade will prevent the plants from emerging too early when it's sunny in the middle of winter.
4. Protect: To prevent squirrels or rodents from digging up the outdoor bulbs, you can secure chicken wire tightly over the pot or try Raven's method: sprinkle chili powder and chili flakes over the soil, followed by a layer of prickly twigs and branches (e.g. thorny rose cuttings).
Top flower bulb combinations for layered planting
Raven is famous for her elegant bulb containers. Here are some of the combinations she plants year after year.
Jonathan Buckley. From A YEAR FULL OF POTS: CONTAINER FLOWERS FOR ALL SEASONS by Sarah Raven, from Bloomsbury Publishing
Fragrant
“I love fragrant tulips, so any mix, including 'Ballerina,' is a winner,” says Raven. Your current favorite lasagna combination, above: 'Ballerina' with the bright pink 'Mariette' and the crimson 'Sarah Raven' tulip (which just won a prize from the Royal Horticultural Society).
Monochromatic
Raven loves staying true to a simple, calm color palette and combining different white tulips with different bloom times. In a flower box she likes to combine the “Ice Stick” and “White Valley” daffodils with the “Starlight Sensation” daffodils. It's a combination that delivers “a spring-like bloom, fragrance and quiet glamour,” says Raven.
Richly colorful
For a bolder color palette, try tulips in shades of orange, deep red and dark purple. Raven chooses bulbs in these shades from her own Venetian tulip collection – 'Prinses Irene', 'Couleur Cardinal' and 'Havran'. “I've added to this combination every year for almost 20 years and still love it,” says Raven. “I would stick Iris reticulata 'George' or something similar at the top to add bonus February blooms and color.”