Whoever wants a sea of tulips, daffodils and crocuses in April must think of it in autumn. Bulbs need the cold season in the ground to sprout in spring. Planting is easy, but a few mistakes cost the bloom: set too shallow, the wrong way round, or eaten by the vole.
Three things you must get right: the depth, the timing and protection from rodents. This article shows you how your bulbs reliably come through winter and open up in spring.
Twice as deep as tall
The most important rule fits in one sentence: plant each bulb about twice as deep as it is tall itself. A large tulip bulb of five centimetres therefore goes about ten centimetres deep, small crocuses correspondingly shallower.
Bulbs set too shallow freeze more easily, sprout unstably and are heaved out of the ground by frost. Too deep ones cost needless energy when sprouting. The tip always points up, the flat end with the root base down. With round bulbs where you cannot tell, lying on the side does no harm, the shoot finds its way up on its own.
The right timing
Bulbs want to root before the permanent frost. The best window is autumn from weeks 39 to 46, that is late September to mid-November. Early bloomers like daffodils may go earlier, tulips even tolerate late planting, as long as the soil is open.
The only thing that matters: the soil must not yet be frozen through. As long as you can dig a planting hole without trouble, planting is possible. A handful of sand in the planting hole improves drainage on heavy soils and protects against rot.
Decide on the spot and groups
Choose a place that is sunny in spring, under deciduous shrubs this is often part-shade too. Plan the bulbs in groups, not in straight rows.
Planting hole at the right depth
Dig a hole of twice the bulb height depending on bulb size. For a whole group it is best to lift out a shallow hollow instead of setting each bulb singly.
Set bulbs with the tip up
Set the bulbs about one bulb-width apart, tip up. On heavy soil a handful of sand goes under the bulb.
Use a basket where voles are present
In gardens with voles, set the group in a planting basket of fine wire mesh. That protects above all the coveted tulips reliably.
Firm and water in
Fill the hole with soil, press it down lightly and water once thoroughly. That closes cavities and stimulates root formation.
Twice as deep as tall, tip up, in groups and in good time in autumn. Whoever heeds this has a sea of flowers in spring instead of bare soil.
The core rule for bulbs
Frequently asked questions
How deep do you plant bulbs?
As a rule of thumb about twice as deep as the bulb is tall. A five-centimetre tulip bulb therefore goes about ten centimetres deep into the soil, small crocuses and snowdrops correspondingly shallower.
When do you plant bulbs for spring?
In autumn, best from weeks 39 to 46, that is late September to mid-November. Decisive is that the soil is not yet frozen through, so the bulbs can root before winter.
Which side of the bulb goes up?
The tip points up, the flat end with the root base down. With round bulbs where you can barely tell, it does not matter: the shoot grows up on its own.
How do I protect bulbs from voles?
Most safely with a planting basket of fine wire mesh into which you set the bulbs. Alternatively plant species avoided by rodents like daffodils, ornamental onion and crown imperial, which count as inedible.
Do I have to water bulbs after planting?
Yes, once thoroughly after planting. That closes cavities in the soil and stimulates root formation. Afterwards the natural rainfall over winter is usually enough.
