Complete guide to planting bulbs

Bulbs are an important element in any garden – they provide swathes of brilliant colour not only in spring but across the seasons. Some of our favourite garden plants grow from bulbs, from welcome snowdrops and crocuses in late winter, daffodils and tulips in spring, lilies, gladioli and dahlias in summer and nerines and colchicums in autumn. 

Planted when dormant, bulbs are small powerhouses that burst into flower a few months later, giving a stunning display of colourful flowers. The term ‘bulb’ often refers not only to true bulbs such as such as daffodils and tulips, but also tubers, corms and rhizomes.  

There are two main planting times for bulbs. Spring-flowering bulbs, such as crocus, daffodils, tulips and alliums are planted in autumn; they then die back and go dormant in summer. Summer-flowering bulbs, such as dahlias, lilies and gladioli, are planted in spring; they go dormant in winter. 

With a little forward planning, you can be enjoying bursts of colour from bulbs throughout almost all of the year. Most grow extremely well in pots and many are attractive to pollinators. For the best results, buy more than you think – for bulbs to really make an impact, they look best planted en masse.

More on growing bulbs:

• Bulb types explained
• Spring bulbs to plant in autumn
• What to plant with spring bulbs
• The best bulbs for pots

Growing bulbs: jump links

• When to plant bulbs
• Where to plant bulbs
• Bulb planting depths
• How to plant bulbs
• Buying bulbs

When to plant bulbs

September and October
Snowdrops, Iris reticulata, crocus, grape hyacinth (Muscari), narcissi (daffodils), hyacinths, crown imperial (Fritillaria imperialis), snakeshead fritillary (Fritillaria meleagris), alliums,  camassia, nectaroscordum

November
Snowdrops, crocus daffodils, grape hyacinth (Muscari), tulips,  crown imperial (Fritillaria imperialis), camassia 

December
Tulips

April and May
Lilies, dahlias, cannas, crocosmia, gladioli, eucomis, nerines, anemone, begonia

August
Autumn-flowering crocus (colchicums)

Where to plant bulbs

Most bulbs need a sunny spot, and well-drained soil. Some bulbs, such as snowdrops or narcissi, will also grow in partial shade. Many bulbs look great planted in drifts among perennials in borders; spring bulbs look particularly good when planted under a deciduous shrub in a border.

Most bulbs grow extremely well in pots.

• 10 of the best bulbs for pots

You can also grow some bulbs in lawns, wildflower meadows or around the base of trees – they will then naturalise over the years, creating a natural-looking drift.

• How to plant bulbs in lawns

Bulb planting depths

When planting bulbs, it’s important to plant them at the right depth to ensure you get to enjoy the flowers. Bulbs that are planted too deeply may produce only foliage at the expense of flowers, or not emerge at all. Too deeply is better than too shallow, however – the bulbs are at greater risk of being dug up accidentally, or by squirrels, which will feast on the nutritious bulbs.

Generally, the rule of thumb is to plant bulbs at three times their depth, but there are exceptions to the rule.

Spring-flowering bulbs

Snowdrops: 10cm or three times their depth
Iris reticulata: 10-15cm 
Crocus: 10cm or three times their depth
Daffodils: 15cm or three times their depth
Hyacinths: 10cm or twice their depth 
Tulips: 20cm or three times their depth
Fritillaria imperialis, crown imperials: 30cm or three times their depth
Fritillaria meleagris, snake’s head fritillary: 10cm or five times their depth
Globe alliums: 30cm or three times their depth
Allium sphaerocephalon: 15cm or three times their depth
Camassia: 10-15cm deep, or around twice the height of the bulb

Summer-flowering bulbs

Eucomis: 15cm 
Lilies: 15cm or three times their depth
Gladioli: 15cm deep
Crocosmia: 10cm or three times their depth
Dahlias: just below the soil surface (start them off in a pot under cover)
Cannas: ensure that the top of the corm is just above the surface?
Nerines: just below the soil surface

How to plant bulbs

How to plant bulbs in the ground

Most bulbs enjoy well-drained soils. If you have heavy soil, plant bulbs that’ll enjoy it, like snake’s head fritillaries, or improve the soil drainage with well-rotted organic matter such as garden compost or well-rotted manure. You could also add some horticultural grit or sand at the base of each planting hole to improve drainage.

Step 1
Dig a hole wide and deep enough for your bulbs, using a trowel or bulb planter. Plant most bulbs at two to three times their depth. 

Step 2
Place the bulbs in the hole with their pointed end facing upwards (check the packet instructions for corms and tubers). Space the bulbs at least twice the bulbs’ width apart.

Step 3
Fill the planting hole back in. If you like, you can mark the spot with a label or stick.

Step 4
If you’re planting bulbs in autumn and the soil is already moist, there is no need to water the bulbs in – they will get plenty of moisture over the coming months from rainfall. If planting bulbs in spring, water them in after planting.

How to plant bulbs in containers

In pots, bulbs can be planted less deeply and closer together. You can pot up different bulbs in different pots, which means you can rotate the display, bringing those at their peak to the fore. Use a peat-free, multipurpose compost – you could add some horticultural grit for added drainge. For the best display, bulbs in pots are best replaced annually. 

Step 1
Add some crocks at the bottom of the pot for drainage.

Step 2
Add some compost at the base of the pot. If you’re planting up a large pot, a depth of around 10cm is ideal.

Step 3
Add your bulbs, pointed end up, around 1-2cm apart.

Step 4
Top up the pot with compost and water in well.

You can pot up different bulbs in different pots, which means you can rotate the display, bringing those at their peak to the fore. Alternatively, layer bulbs for maximum impact and a continuous succession of flowers.

Watch Monty Don layering bulbs in a pot in this video: