Discover when to Plant Spring Bulbs

 Spring Bulbs are in the shops sooner each year but there is much debate about when you should plant them. Some gardeners swear you have to wait until there has been a frost. Others say you must expose the bulb to the cold for a spell or even wait until the ground is hard. It is it is important to understand the life cycle of a bulb though to see the best time for planting. 

Winter

Bulbs are mainly dormant during winter. Doing virtually nothing while the temperature is low and the conditions unfavourable for growth. Something is happening though. Most spring bulbs need a certain amount of cool weather in order to initiate flowering which is generally not a problem in the UK. The temperature needed varies between different flowers which explains why some years you may have stunning tulips (need a lower temp) and mediocre daffodils.

If you aren't in the UK and live in an area with higher temperatures you can purchase pre-chilled bulbs that have been exposed to the cold. These will ensure flowering without the cold spell. 

Spring

In Spring the energy stored in the bulb is used to grow leaves. These start to photosynthesize to replenish the food used for early spring growth and to provide energy to produce flowers and ultimately seeds. 

Summer

By mid-summer the plant has finished its above ground growth. The leaves begin to die back. What is less well known is that below ground the roots die back too and stop working. The plant isn't actively growing so doesn't need roots at this stage. 

Autumn

Towards the end of summer conditions trigger the bulb to start growing roots again. Once the roots are functioning and accessing water and nutrients the bulb then starts to grow leaves and flowers. These grow until they are just below the surface of the soil. You'll see this if you accidentally dig up a bulb (or deliberately dig one up to see now that you are curious!!)

The reason for this is when you are a bulb, Spring is your time to shine. Temperatures are cool and light is scarce so you have to get on with it. You have to produce leaves, flowers and seeds before shrubs, trees and other plants eclipse you and steal your sunlight. Doing as much of your growing as you can in Autumn makes sense. This all stops when it get really cold, and the bulb goes into its dormant state again.

Reasons to Plant Late

I have searched and can find little reasoning for planting late other than "this is what I have always done, and George* on the next plot told me to so it must be true" (*insert name of the person on your plot who knows everything!) I think that the idea of giving the bulbs some exposure to the cold comes from the fact that tulips and other bulbs will not flower in warm climates. They do need a chill period during winter to flower. Knowing this, you can see why people might think that it is best to plant after a frost. Another explanation is that early planting will expose them to too much warm weather during late Summer, resulting in early growth that will be harmed by frosts. This explanation makes no sense when you consider the bulbs planted in past years don't seem to suffer from this problem.

Reasons to Plant Early

The logic of planting later or after frost etc is blown out of the water by the fact that those bulbs already in the ground are producing roots. It is common sense that a plant is only as good as its root system as this provides the water and nutrients the plant needs to thrive. So if bulbs start to produce roots from late August there is a strong case that this is the time to start planting new bulbs. This will allow them to become well established before the dormant stage is reached. 

How to Plant Spring Bulbs

1. Make sure you have healthy bulbs - they should be firm and plump, not withered or spongy. Watch out for signs of mould too and discard any mouldy ones.
2. Choose the right location - most bulbs (except some woodland varieties) need full sun and good drainage. Remember that the trees won't have leaves when the bulbs flower so utilise these areas too.
3. Bulbs look best in clumps or drifts. So to get a natural looking display, plant several bulbs together. Or if you are feeling adventurous, throw the bulbs into the air then dig holes and plant wherever they fall.
4. Plant bulbs to a depth of about three times their diameter. If you have a problem with pests like squirrels or blackbirds digging up your bulbs then plant them into Rootrainers and then transfer once the roots are stronger and harder for the pests to pull out.
5. Replace the soil after planting and water the bulbs to help them establish.

Lasagna planting for Spring Bulbs

If you want to have a continuous display then give lasagna planting a go. This is basically planting different bulbs at different levels so that you get a continuous display of flowers throughout spring. Planting depth is determined by the size of the bulb. Plant the latest flowering (which are generally the largest) first. It can be done either in pots or in the garden itself. 

Lasagna Planting in Pots

1. Choose your bulbs. Ones to consider include: Daffodils, Tulips, Crocus, Snowdrops, Hyacinth, Muscari, Dwarf Iris and Allium. All have different flowering times. Even different daffodils or tulips have different bloom times so you could stick to one flower type. Whatever flowers you choose, consider that their flowering times may overlap so they need to look good together and select ones that bloom at different times to make sure your have a continuous display.
2. Put some gravel in the bottom of your pot and add 8-10cm (3-4") of compost.
3. Start with your largest bulbs. - place in a ring around the pot.
4. Add another 8-10cm (3-4") of compost and continue layering up like this until the pot is full then water well.
5. You may then want to plant some bedding plans such as cyclamen on top for winter colour while you wait for your lasagna to cook!

To achieve this effect in the garden just follow the same process starting with a fairly deep hole and filling in as you go. You should have a Spring full of lovely flowers and the pollinators will love you for it!

Did you know?

Lilies and Tulips should never be planted together because they suffer from the same diseases.

And, tulips should not be planted in the same spot for 2 consecutive years, but if African Marigolds are planted where the tulips have flowered there will be no problem in using the same spot again.