Germination Troubleshooter
Seeds Not Germinating?
Answer a few questions and we will diagnose the problem.
What happened with your seeds?
How long have you been waiting?
What is the temperature where your seeds are?
What germination method are you using?
Are the paper towels still moist?
How long is the taproot?
What is the environment like?
What did the seedling look like when it died?
Where did you notice the mold?
How long has it been?
Give It More Time
What is happening
Many seeds take 3-5 days to crack open. Some sativa-dominant strains and haze crosses can take up to 7 days. This is completely normal and not a sign of a problem.
What to do now
- Keep conditions stable: 70-90°F (21-32°C), damp (not wet) towels or moist soil
- Check twice daily, morning and evening
- Do not open the dome more than necessary
- Do not move or disturb the seeds
Prevent this next time
Check your strain info before germinating. Autoflowers typically germinate fastest (24-48 hours). Sativas and haze genetics can take 5-7 days. Set realistic expectations based on what you are growing.
Too Cold
What is happening
Seeds need 70-90°F (21-32°C) to germinate. Below 65°F (18°C), the enzyme activity needed for the embryo to break the shell slows dramatically or stops entirely.
What to do now
- Move your seeds to a warmer location immediately
- Use a seedling heat mat set to low (75-80°F / 24-27°C is ideal)
- Top of a refrigerator, near (not on) a radiator, or in a warm closet can work
- The seeds may still be viable if they have not been cold for too long
Prevent this next time
Use a thermometer to verify the temperature where your seeds are germinating. Room temperature can be deceiving because countertops, windowsills, and basements are often cooler than the ambient air. The sweet spot is 75-80°F (24-27°C).
Too Hot
What is happening
Temperatures above 90°F (32°C) can cook the embryo inside the seed and kill it. Heat mats on high, direct sunlight, and radiators are common culprits.
What to do now
- Move seeds away from the heat source immediately
- If using a heat mat, turn it to its lowest setting or add a layer between the mat and the seeds
- If the seeds have been above 90°F for more than a few hours, they may not recover
- Start with a fresh seed in a temperature-controlled location if needed
Prevent this next time
Always use a thermometer. Heat mats without a thermostat controller can easily overshoot. The target is 75-80°F (24-27°C). Never place seeds in direct sunlight during germination.
Likely Non-Viable Seed
What is happening
After 7+ days with correct temperature and consistent moisture, the seed is almost certainly not viable. This can happen with older seeds, seeds stored improperly, or occasionally due to natural variation.
What to do now
- Try a fresh seed from the same pack using the paper towel method
- If multiple seeds from the same pack fail, contact Seedbank support
- Have your order number, germination method, and photos ready
- We stand behind our seeds and will make it right
Prevent this next time
Store seeds in a cool, dark, dry place. A sealed container in the refrigerator is ideal for long-term storage. Avoid exposing seeds to light, heat, or humidity until you are ready to germinate. Properly stored seeds can last 3-5 years.
Seeds Dried Out
What is happening
Paper towels can dry out in just a few hours in warm, dry environments. Once the seed dries out after absorbing water, the embryo can die. The germination process requires continuous moisture once it begins.
What to do now
- Re-dampen the towels immediately with distilled or filtered water (do not soak)
- If the seed has been dry for less than 12 hours, it may still recover
- If dry for more than 24 hours, the seed is likely lost
- Seal the container or plate with a dome, lid, or plastic wrap
Prevent this next time
Always use a sealed container or dome over your paper towels. Check moisture levels twice daily (morning and evening). The towels should feel like a wrung-out sponge: damp throughout but not dripping.
Planted Too Deep or Soil Too Dense
What is happening
Seeds planted deeper than 1/2 inch may not have enough energy to reach the surface. Dense, compacted soil can also restrict the taproot from pushing through, trapping the seedling underground.
What to do now
- Gently check if the seed has sprouted below the surface by carefully brushing away the top layer of soil
- If you find a seedling trying to push through, carefully reposition it at 1/4 inch depth
- Consider switching to the paper towel method for better visibility
- If starting over, use a light, airy seed-starting mix
Prevent this next time
Plant seeds only 1/4 inch (6mm) deep. Use a loose, well-aerated seed-starting mix rather than heavy garden soil. Do not press or compact the soil over the seed. The paper towel method eliminates this variable entirely.
Seeds Were Submerged Too Long
What is happening
We recommend the paper towel method instead of soaking as a standalone approach. The water glass should only be used as a 12-24 hour pre-soak before transferring to paper towels. Seeds submerged longer than 24 hours can drown because the embryo needs oxygen to develop. Extended submersion cuts off the air supply.
What to do now
- Remove the seeds from the water immediately
- Transfer to damp paper towels (wrung-out sponge moisture level)
- If the seed has sunk to the bottom, that is a good sign: it means the shell has absorbed water
- If the seed feels soft or mushy, it may already be lost
Prevent this next time
Skip the soak and go straight to the paper towel method. It gives full visibility, control, and the highest success rate. Only use a 12-24 hour water soak as a pre-treatment for old or hard-shelled seeds, and even then transfer to paper towels immediately after. Set a timer so you do not exceed 24 hours.
Taproot Dried Out
What is happening
The taproot is the most vulnerable part of the germinating seed. Once exposed to dry air, it can die within hours. A healthy taproot is white and firm. A dead taproot turns brown, brittle, or shriveled.
What to do now
- Re-moisten the towels immediately and seal the container
- If the taproot is still white and firm, it may recover
- If the taproot has turned brown, brittle, or shriveled, the seed is lost
- Start with a fresh seed if the taproot is dead
Prevent this next time
Once you see a taproot, check moisture every 6-8 hours and keep the dome tightly sealed. The taproot stage is the most critical. Consider planting into soil as soon as the taproot reaches 1/4 inch rather than waiting longer.
Taproot Suffocated (Overwatering)
What is happening
The taproot needs both moisture and oxygen. Paper towels that are soaking wet or dripping suffocate the root. If the taproot has turned dark and soft, root rot has set in.
What to do now
- Drain all excess water from the plate or container
- Re-dampen towels to the "wrung-out sponge" level: damp throughout, not dripping
- If the taproot is still white, it should recover with corrected moisture
- If the taproot is dark and soft, start with a new seed
Prevent this next time
After dampening your paper towels, wring them out thoroughly. There should be no pooled or standing water on the plate. The towels should be uniformly damp but you should not be able to squeeze water out of them.
Cold Shock After Germination
What is happening
A sudden temperature drop after germination begins can halt taproot growth. The embryo is actively developing and is sensitive to environmental swings, especially cold.
What to do now
- Move the seeds to a stable 75-80°F (24-27°C) environment
- If the taproot is still white and firm, the seed may recover with warmth
- Give it another 24-48 hours in stable conditions before giving up
- Do not try to warm it quickly (no direct heat sources)
Prevent this next time
Keep germinating seeds away from windows, exterior walls, and drafty areas. Nighttime temperature drops are a common culprit. A seedling heat mat with a thermostat controller provides the most stable environment.
Your Seed Is Ready to Plant!
What is happening
A taproot at 1/4 to 1/2 inch is the ideal length for planting. Your seed has successfully germinated. The taproot has not stopped growing; it is ready for soil.
What to do now
- Transfer immediately to pre-moistened growing medium
- Place the seed taproot pointing down, covered with 1/4 inch of soil
- Do not press or compact the soil; just lightly cover
- Water gently and place under light (18/6 cycle)
- Do not wait for the taproot to grow longer. Longer taproots are more fragile and harder to handle without damage.
Next steps
Your seedling should emerge from the soil within 24-72 hours. Keep the soil moist (not wet) and the humidity high (60-70%). A clear dome or plastic wrap over the pot helps retain humidity during this stage.
Not Enough Light (Stretching)
What is happening
The seedling stretched toward the nearest light source and became too thin and weak to support itself. This is called etiolation. The stem grew long and spindly instead of short and sturdy because it was searching for adequate light.
What to do now
- Provide immediate light: 18 hours on, 6 hours off cycle
- Use a T5 fluorescent or LED grow light positioned 6-12 inches above the seedling
- A stretched seedling can sometimes be saved by transplanting deeper so the weak stem is supported by soil
- Gently support the stem with a small stake or toothpick if it cannot stand on its own
Prevent this next time
Have your light ready before the seedling emerges. As soon as you see green breaking through the soil, the light should be on. A sunny windowsill is usually not enough. Seedlings need direct, close-range light from day one.
Damping Off (Fungal Infection)
What is happening
Damping off is a fungal infection that attacks the stem at the soil line, causing it to thin, turn brown, and collapse. It is caused by overwatering, poor drainage, stagnant air, or contaminated growing media. Once it starts, the affected seedling cannot be saved.
What to do now
- The affected seedling is lost. Remove it and dispose of the soil.
- Sterilize the container with a dilute hydrogen peroxide solution before reusing
- Start over with fresh, sterile seed-starting mix
- Use a new, clean container
Prevent this next time
Use sterile seed-starting mix (not garden soil). Do not overwater. Ensure containers have drainage holes. Provide gentle air circulation (a small fan on low nearby). Let the soil surface dry slightly between waterings. Sterilize all containers and tools before use.
Overwatering or Nutrient Burn
What is happening
Seedlings need very little water and zero added nutrients for the first 1-2 weeks. Yellow leaves and wilting are classic signs of overwatering (roots suffocating) or nutrient burn (soil too "hot" for delicate seedlings).
What to do now
- Stop watering and let the top 1/2 inch of soil dry out before watering again
- If using nutrient-rich soil (like Fox Farm Ocean Forest), transplant into a mild seed-starting mix
- Do not add any liquid nutrients until the seedling has at least 3-4 sets of true leaves
- Ensure your container has drainage holes so excess water can escape
Prevent this next time
Start seedlings in a mild, low-nutrient seed-starting mix. Water only when the top 1/2 inch of soil feels dry to the touch. Seedlings in small pots need surprisingly little water. When in doubt, wait another day before watering.
Heat Stress or Low Humidity
What is happening
Curled leaves with crispy edges indicate the seedling is losing moisture faster than its small root system can absorb it. This happens when temperatures exceed 85°F (29°C) or humidity drops below 50%.
What to do now
- Move the seedling to a cooler location: 70-80°F (21-27°C) is ideal
- Increase humidity with a clear dome or humidity tent over the seedling
- Move grow lights further away if they are generating too much heat
- Mist the inside of the dome (not the seedling directly) if humidity is very low
Prevent this next time
Keep seedlings at 70-80°F with 60-70% humidity for the first week after emergence. Use a humidity dome for the first 3-5 days. Remove the dome gradually over 2-3 days to acclimate the seedling.
Contamination on Paper Towels
What is happening
White fuzzy mold on the paper towels means the environment is too wet and lacks air circulation. Mold spores are everywhere and they thrive in warm, wet, stagnant conditions. The seeds may or may not be affected depending on how advanced the mold is.
What to do now
- Start fresh: new plates, new paper towels, wash your hands first
- Dampen towels to the "wrung-out sponge" level, not soaking wet
- If the seed itself looks healthy (firm, not soft), it can be reused
- Open the dome briefly (30 seconds) twice daily for air exchange
Prevent this next time
Use clean plates and fresh paper towels. Wash your hands before handling seeds. Keep towels damp but not dripping. Provide brief air exchange twice daily by cracking the dome. Do not use towels with added fragrances, dyes, or lotions.
Seed Rot from Overwatering
What is happening
The seed absorbed too much water and the embryo inside has died. A rotted seed feels soft, squishy, and may have a foul smell. This usually happens from soaking too long (over 24 hours) or paper towels that are dripping wet rather than damp.
What to do now
- There is no saving a rotted seed. Discard it.
- Start with a fresh seed and reduce the moisture level
- Dampen towels to "wrung-out sponge" level: uniformly moist, no dripping
- If you were soaking in water, limit the soak to 12-24 hours maximum
Prevent this next time
Less water is almost always better than more. The towels should be damp, not wet. There should be no standing water on the plate. If soaking first, set a timer for 18-24 hours and transfer to towels promptly.
Mold on Soil Surface
What is happening
Green or dark mold on the soil surface means the growing medium is staying too wet, has poor drainage, or was already contaminated. Surface mold does not always kill the seed, but it indicates conditions that can lead to damping off once the seedling emerges.
What to do now
- Gently scrape off the top layer of moldy soil and discard it
- Let the soil surface dry out before watering again
- Ensure the container has drainage holes
- A light dusting of cinnamon powder on the soil surface acts as a natural antifungal
- Improve air circulation around the container
Prevent this next time
Use well-draining seed-starting mix with perlite. Ensure containers have drainage holes. Water less frequently. Let the soil surface dry slightly between waterings. Provide some air movement near the containers.
Slow but Normal
What is happening
Most seeds germinate in 24-72 hours, but 3-5 days is still well within the normal range. Sativa-dominant strains, haze crosses, and older seeds are often slower germinators. This is not a sign of failure.
What to do now
- Verify your temperature is stable at 75-80°F (24-27°C)
- Confirm the paper towels or soil are still moist
- Do not disturb the seed. Checking too often can disrupt the process.
- Check twice daily (morning and evening) and otherwise leave it alone
Prevent this next time
Patience is the most important tool in germination. If you are anxious about slow seeds, try starting with autoflower strains, which tend to germinate fastest (often within 24-48 hours).
Likely Failed - Contact Support
What is happening
After 10+ days with correct conditions (70-90°F, consistent moisture), the probability of germination is very low. The seed may have been non-viable, stored improperly, or damaged during shipping.
What to do now
- Contact Seedbank support. We stand behind our seeds and will help make it right.
- Have the following ready: your order number, the germination method you used, the temperature range, and photos of your setup
- Try a fresh seed from the same pack using the paper towel method while you wait for our response
- If multiple seeds from the same pack fail, let us know. This helps us track batch quality.
Prevent this next time
Store unused seeds in a cool, dark, dry place (a sealed container in the refrigerator is ideal). Use the paper towel method for the best visibility and control. Verify temperature with a thermometer. Follow our step-by-step guide for the best results.