To plant bulbs successfully, it’s important to plant at the right time and depth with the bulb the right way up. You can ensure showstopper blooms by fertilising when planting, and as long as there is vegetative growth in the growing season. Applying mulch in winter will help protect spring-flowering bulbs from frost injury.
When To Plant
If ordering online, plant as soon as you receive the bulb, or store in a dry, dark location if you can’t plant immediately. Leave a bulb unplanted and it may fail to flower or flower poorly. If you forget to plant, examine by touch, and discard soft or rotten bulbs. Others are worth a shot.
Generally, spring flowering bulbs need to be planted by the end of September, which will allow time for the bulb to root before the ground freezes. Tulips are planted in October and November, depending on whether you are in the North or South respectively, which helps reduce problems with disease.
Hardy summer flowering bulbs are to be planted in September and October, while tender summer flowering bulbs in early spring. Autumn flowering bulbs need to be planted by late summer.
|Bulb||Season||Planting depth||Planting distance between bulbs||Position|
|Allium||Autumn||10cm (4″)||10cm (4″)||Full sun|
|Begonia||Spring||1cm (1/2″)||30cm (12″)||Full sun, semi shade, dappled shade|
|Crocus||Autumn||10cm (4″)||7cm (3″)||Full sun, semi shade|
|Daffodil||Autumn||10cm (4″)||10cm (4″)||Full sun, semi shade|
|Dahlia||Spring||15cm (6″)||45cm (18″)||Full sun|
|Bluebell||Spring/Autumn||10cm (4″)||10cm (4″)||Dappled shade|
|Gladiolus||Spring||10cm (4″)||15cm (6″)||Full sun|
|Hyacinth||Autumn||10cm (4″)||8cm (3″)||Full sun, semi shade|
|Iris reticulata||Autumn||10cm (4″)||8cm (3″)||Full sun|
|Lily||Autumn||20cm (8″)||15cm (6″)||Full sun, semi shade|
|Narcissus||Autumn||10cm (4″)||10cm (4″)||Full sun, semi shade|
|Ponerorchis||Spring||2.5cm (1″)||7cm (3″)||Dappled shade|
|Ranunculus||Autumn||8cm (3″)||25cm (10″)||Full sun|
|Snowdrop||Spring/Autumn||10cm (4″)||10cm (4″)||Dappled shade|
|Tree Lily||Autumn||20cm (8″)||15cm (6″)||Full sun, semi shade|
|Tulip||Autumn||15cm (6″)||13cm (5″)||Full sun|
|White Egret Orchid||Spring||2.5cm (1″)||7cm (3″)||Dappled shade|
|Winter Aconite||Autumn||5cm (2″)||5cm (2″)||Full sun, semi shade, dappled shade|
As always it’s best to look at a species habitat and flowering time when deciding where to plant. Early spring bulbs such as snowdrops are used to harsh conditions, and will thrive in cold pockets. Forest dwelling species such as the bluebell are used to dappled shade, and will thrive under any deciduous tree. More exotic species such as dahlia, originating from Mexico, are suited to full sun.
It’s not the end of the world if you plant in a sub-optimal location as bulbs are a storage organ and the plant already has a large reserve of energy. Bulbs rarely thrive in deep shade and output will be poor in the second year after planting.
It’s possible that southern exposure can lead to early emergence and freezing injury. You can moderate temperature extremes by applying 3 inches of mulch after the first frost. This will help prevent injury from the constant cycle of frost and thaw. Remove the mulch if you think the shoots can’t penetrate it easily.
The key message is to avoid waterlogged soils, which can starve a bulb of oxygen, causing them to rot. Clay soils usually have poor drainage, and can be improved by adding organic mulch. Ensure you don’t compact the soil, but firm with the back of a rake.
Most bulbs have a tip, which should be pointing upwards when planted. Some will arrive with roots on the bottom, opposite to the tip. Begonia bulbs do not have a sharp point, but you can sometimes detect the tip emerging out of the concave (indented) side.
Planting Depth & Distance
A general rule of thumb is that bulbs can be planted three times their height, although begonias are an exception to this.
Bulbs in containers can be spaced a bulb width apart. In the ground, 2-4 inches is common for small and 8 inches for large bulbs.
Apply phosphorus when planting as it doesn’t travel well in the soil. This essential nutrient helps with root growth.
Water immediately after planting, unless you are planting in autumn and the ground is already wet.
Sometimes, small mammals will dig up bulbs, but this can be prevented with wire mesh.
Plants in containers are vulnerable to drought and under fertilisation, so water and feed regularly once the growing season starts.
As nutrients are absorbed through roots, it’s important nutrients reach the depth the roots are located. Liquid fertiliser will penetrate the soil, and can remedy deficiencies quickly, but is liable to leeching. Other inorganic fertilisers will fertilise the soil over time, so need to be applied in advance. Organic fertiliser takes far longer as it’s insoluble and first needs to be broken down by microorganisms, before becoming available for uptake by plants.
Removing seed pods, but maintaining foliage, allows a plant to put more energy into its bulb, for larger blooms thereafter. Watering and feeding will help with this. Remove foliage once it yellows.
After this, bulbs can be lifted, sorted, washed, left to dry and then stored in a cool, dry, airy place. Small, rotten or diseased bulbs are best thrown.
Jorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!
His ideal afternoon would involve a long walk, before settling down for scones.
Jorge is a journeyman gardener with experience in growing crops.