When planting flower bulbs, the question of the optimal planting depth inevitably arises. Specimens planted too deeply may not sprout. Onions that are not planted deep enough will not have enough support. Are there any defined values for this?
What is the correct planting depth for flower bulbs?
The optimal planting depth for flower bulbs varies depending on the variety and bulb size, although the rule of thumb is that the planting depth should be twice the bulb length. Examples of planting depths: hyacinths 10-12 cm, crocuses 5-8 cm, daffodils 10-15 cm, tulips 10-15 cm.
The term planting depth
What do you understand by the term planting depth? In fact, not even the experts agree on the definition. Is this the distance from the bottom of the planted bulb to the surface of the earth? Or is that the height of the soil layer above the bulb?
Luckily the onion itself doesn't take it too seriously. In order for it to sprout after planting, the optimal distance does not have to be maintained exactly.
Onion size
The size of the bulb is the most important indication of how deep your planting hole needs to be. Since there are both huge varieties of flower bulbs and tiny little bulbs, it is understandable that a different planting depth applies to each variety. The rule of thumb is: the planting depth is twice the bulb length.
The Floor
The layer of soil above an onion is a barrier that it first has to break through with the tender, thin shoots. The thicker the layer, the more work the onion has to do. Depending on the nature of the soil, sprouting can even fail.
- in a light soil of deep plants
- plant less deeply in heavy soil
Top-heavy plants
Some flower bulb varieties, such as some Allium species, sprout heavily or high above ground and must therefore be well rooted in the soil. For these varieties, the planting depth is not calculated based on the bulb size. They have to go a little deeper into the ground to ensure good stability.
Don’t plant too deep
The recommended planting depth does not have to be adhered to to the millimeter. But there shouldn't be any major deviations. Flower bulbs planted too deep grow worse. The flower is also not as magnificent as it could be naturally.
Planting depths of popular varieties
- Hyacinths: 10 to 12 cm
- Imperial crowns: 25 to 30 cm
- Crocuses: 5 to 8 cm
- Märzenbecher: 8 to 10 cm
- Daffodils: 10 to 15 cm
- Checkerboard flower: 5 to 7 cm
- Snowdrop: 7 to 10 cm
- Rad anemones: 5 cm
- Grape hyacinths: 5 to 7 cm
- Tulips: 10 to 15 cm
- Ornamental onion: 10 to 15 cm
- Dwarf iris: 5 to 7 cm
