Discover 38 types of seeds you should freeze before planting to ensure better germination!
There are certain seeds in the plant kingdom that you should freeze to avoid a poor germination rate after planting and if you are wondering why, read below!
Check out here the simple seed germination tips to grow every seed
Why Should You Do this?
It is a process that seeds undergo to mimic the winter for breaking their dormancy to kickstart germination. It’s especially crucial for plants native to cooler climates.
Artificially, gardeners can replicate this process using refrigeration. Please note that the stratification periods vary in duration; some seeds may require a few weeks to several months of cold exposure.
Best seeds for gardening that grow quickly in just 5 days
Seeds to Freeze Before Planting
1. Hops
Duration: 4-8 weeks
Once done, you can plant the seeds indoors or outdoors when the weather warms up a bit.
2. Viburnum
Duration: 4-12 weeks
Cold stratification helps in ensuring the successful germination of Viburnum seeds. Studies have shown that stratified seeds generally exhibit higher germination rates.
3. Arnica
Duration: 8 weeks
After the freezing process, soaking the seeds for 4 hours before stratification (lightly scratching the seed coat) can be helpful to rehydrate them and improve germination rates.
How to grow Arnica montana
4. Black-Eyed Susan
Duration: 4-6 weeks
If you start this 6 to 8 weeks before the last frost, it will be a good strategy for outdoor planting.
5. Redbud
Duration: 5 to 8 weeks
Different Redbud species may have slightly different dormancy requirements. Some, like Eastern Redbud, may require longer stratification periods (up to 8 weeks).
6. Rose
Duration: Around 6-8 weeks (some may not require)
After stratification, sow the seeds in damp sand, vermiculite, or a mixture of perlite and peat moss.
Look at the essential rose care tips for bigger flowers
7. Pear
Duration: 8-12 weeks
After the cold treatment, sow them outdoors at temperatures above 40 °F (4 °C).
8. Catmint
Duration: A day in the freezer followed by 12-24 hours soaking in water.
If planting seeds indoors, starting 6 weeks before the last frost is recommended for optimal development before transplanting outdoors
9. Artichokes
Duration: 2-4 weeks
Artichokes are perennials that naturally flower in their second year. A cold period can trick them into thinking they’ve experienced winter.
Check out the best types of Artichoke plant varieties
10. Anise Hyssop
Duration: 4 weeks
You can also sow the seeds directly into the garden in early fall, allowing them to experience cold stratification during the winter months.
11. False Sunflower
Duration: About 4 weeks
False Sunflower seeds can also naturally be sown in winter. Planting can be done indoors or outdoors, both.
12. Goldenrod
Duration: 8 weeks
You can also achieve this process by sowing the seeds outdoors in late fall or early spring, allowing the seeds to be naturally exposed to prolonged cold.
13. Heather
Duration: 6 weeks
After this cold treatment, the seeds take about 1 to 2 months to germinate.
Learn here how to grow heather in pots
14. Larkspur
Duration: 1-2 weeks
After cold stratification, start planting seeds indoors about eight weeks before the last frost of spring or directly in flower beds in early summer.
15. Lavender
Duration: 4-6 weeks
Place the lavender seeds in potting soil in a ziplock plastic bag and refrigerate it. Also, note that these seeds might be tricky to germinate.
Check out here everything about growing French lavender
16. Soapwort
Duration: About 2-3 weeks
When sowing the seeds (Spring is ideal), provide them full to light shade. Also, note that this plant is best suited to Zones 5 to 7.
17. Swamp Milkweed
Duration: 4-8 weeks
You can plant them indoors in small pots, seed trays, or outdoors after the frost danger is passed.
18. Peach
Duration: 8-10 weeks
Peach seeds must be chilled at an ideal temperature between 35-50°F.
19. Strawberry
Duration: 3-4 weeks
Strawberry seeds need freezing for successful germination. Plant them in a seed starting mix for best results.
Check out here growing strawberries from strawberry scraps
20. Eastern White Pine
Duration: 4-12 weeks
Place the seed in a freezer bag with lightly moistened perlite for two to three months in the refrigerator. Sow them in pots 1/4 inch deep and cover lightly.
21. Raspberry
Duration: At least 5 weeks
Plant the seeds in a spot where they get dappled sunlight, and the germination would take a few weeks.
Check out how to grow raspberries in pots
22. Penstemon
Duration: About 4-5 weeks
Ensure you provide full sun or partial shade, dry to moisture medium, and well-draining soil.
23. Prairie Coneflower
Duration: 7-8 weeks
Plant it in the fall, but if you are planning in spring, then the seeds will require vernalization (prolonged cold period to promote flowering).
24. Prairie Violet
Duration: About 7-8 weeks
Avoid covering the seeds with a growing medium, as they need light for a successful germination.
25. Blueberries
Duration: 8-12 weeks
Before freezing, you must remove the pulp from the seeds. They take 6-8 weeks for germination.
Learn here how to grow blueberries in a container
26. Shooting Star
Duration: 4-8 weeks
The seeds may take up to 5-6 years to reach the flowering phase. It also depends on the light and growing conditions.
27. Marsh Marigold
Duration: 8-12 weeks
The seeds can be planted after the cold treatment directly on the ground. Germination takes place in 5-10 days.
Here is the list of marigold flowers that are worth growing
28. St. John’s Wort
Duration: 3-4 weeks
They prefer well-draining soil and typically take about 2-3 weeks to germinate.
29. Apple
Duration: 2-3 weeks
After the cold period, sow the seeds in an area where they receive direct sunlight.
Here are the popular sweet apple varieties
30. Serviceberry
Duration: 12 weeks
After stratifying the seeds, sow them and maintain a temperature between 70 and 77F (21 and 25C).
31. Oregon Grape
Duration: 8-12 weeks
Sow the seeds into the ground before the first frost. They may take 3-5 weeks to germinate.
32. Wild Columbine
Duration: 6-8 weeks
Cold stratification aids in breaking the dormancy of these seeds, promoting more uniform germination.
33. Butterfly Bush
Duration: About 4 weeks
You can sow the seeds indoors 8 to 10 weeks before the last frost.
Should I cut my butterfly bush to the ground, find out
34. Winterberry
Duration: 7-8 weeks
It is a slow-growing shrub, and its seeds require 1-2 months of warmth before the cold treatment.
35. Sugar Maple
Duration: 10-12 weeks
After the process, it would be a good idea to start the seeds in a tray using a seed starting mix. Once germinated, plant them in the garden.
Check out sugar maple tree growing guide
36. River Birch
Duration: 4-12 weeks
After the process, place the seeds in pots filled with potting soil in a place where they receive bright sunlight.
37. Hawthorn
Duration: 12-17 weeks
Sow stratified seeds directly into the ground or a container after choosing an apt location with plenty of sunlight.
38. Magnolia
Duration: 7-9 weeks
Plant the seeds and cover them with about 1/4 inch of soil until the seedling emerges.
