At the latest when you want to grow plants such as wild garlic or peonies from seeds, you will be confronted with the special requirements of cold germinators. In this article we will explain to you what frost and cold germinators are and how you can reliably germinate their seeds.
Cold and frost germinator definition
Cold germinators are plants whose seeds require weeks of cold stimulus to sprout. The seeds are initially in a resting phase (dormant). Seed dormancy in cold germinators is almost always triggered by a highly concentrated plant hormone (abscisic acid) inside. It prevents the cold-sensitive plants from germinating in autumn and the tender young plants from freezing in the following frost period.
The seeds survive the winter months outdoors. During this time, the abscisic acid is gradually broken down. As soon as the temperatures rise again, the plant hormone content has fallen so much that the seeds sprout.
The term cold germinator combines frost and cold germinators. However, frost germinators require significantly lower temperatures to break seed dormancy than cool germinators adapted to temperate climates.
Which plants are typical cold germinators
There are vegetables as well as ornamental plants and trees that are cold germinators:
- Wild garlic
- Chives
- Dill
- Sage
- Arnica
- Hazelnut
- Apple tree
- Stone fruit such as cherries, plums or mirabelle plums
- Poppy
- Cornflowers
- Violets
- Snapdragons
- Christmas Rose
- Flame Flower (Phlox)
- Primrose
- Forget-me-not
- Lavender
Sowing cold germinators
There are two ways to reliably encourage cold germination to germinate:
Sowing in autumn
Sow cold germinators in November directly into the bed or a sowing container that you simply leave outside. Mark the spot with a plant label so that you can distinguish the germinating seeds from weeds in the spring.
During the winter months you don't have to worry about the seeds. When temperatures rise in spring, the seeds begin to germinate.
Stratifying cold buckets in the refrigerator
To break the cold dormancy, you can also store the seeds in the refrigerator for a few weeks. Proceed as follows:
- Fill a freezer bag with two parts potting soil and one part sand.
- Put in the seeds and mix everything thoroughly.
- Wet the mixture slightly.
- Place the open foil bag in the vegetable compartment of the refrigerator.
- Make sure that the mixture does not dry out and shake it once a week.
- When it gets warmer outside, sow the stratified seeds outdoors.
Tip
Seeds with strong dormancy are available from specialist retailers with an interrupted dormancy phase. The seeds in the bag are in a waiting state, which is achieved by drying. The seeds germinate immediately when they come into contact with moist soil. However, this seed only has a limited shelf life and should be sown promptly.
