Why won't some seeds sprout?
Written by
Julia Anderson
Reviewed by
Prof. Charles Hartman, Ph.D.Understanding why germination is not successful resolves typical gardener frustrations. Several issues, such as temperature extremes, seed age, and planting depth, can cause seeds to fail to germinate. Issues with fungus development and inadequate moisture also affect germination. Being aware of these things means you can add simple solutions to improve success rates.
Viability Issues
- Test seeds using float method: viable seeds sink in water
- Store unused seeds in airtight containers with silica gel packs
- Label seed packets with collection year replacing after 2-3 years
Environmental Factors
- Maintain species-specific temperatures 65-90°F (18-32°C)
- Provide consistent darkness/light per seed requirements
- Ensure proper airflow to prevent fungal growth
Planting Mistakes
- Follow depth guidelines: small seeds surface-sown large seeds deep-planted
- Use sterile seed-starting mix not garden soil
- Avoid compaction allowing oxygen to reach seeds
Temperature mismatches create large failures. Peppers preheat to inches when temperatures drop below 75°F, while lettuce prefers to preheat to meters when temperatures are above 70°F. Soil Thermometers work better here because they measure the soil temperature rather than the air temperature. Heated mats are the solution to cold air, and fans help when excess heat is present, matching the requirements for seed packets.
Fungal issues like damping off wipe out seedlings while you sleep. Prevent contamination by using a 3% hydrogen peroxide solution as a disinfectant on tools and storage containers. Use proper seed spacing to avoid crowding, and water from under the tray irrigation. Remove contaminated plants fully to control transmission.
Light requirements vary greatly among species. Some seeds, such as begonia seeds, require exposure to light, while others, like morning glory seeds, need to be kept in darkness. Research to determine the specific light requirements before planting seeds. When adjusting lighting or covers after germination, do it quickly to avoid leggy growth.
Consistently implement a preventive protocol. Sterilize your containers annually and replace your growing media regularly. Record your planting dates and planting conditions to reference in the future. These repetitive actions assimilate knowledge and build upon it, preventing the same failures from being repeated. You will see steadily improved germination success.
Read the full article: How to Germinate Seeds: 7 Foolproof Steps
