What’s Wrong with My Seedlings? – Pinetree Garden Seeds

When gardening, it’s a known fact that you will have successes as well as failures. The failures can be caused by some sort of outside force that you have no control over (cat digging up your seedlings, a tray of tiny green shoots getting knocked off the table by accident, etc.), but it can also be caused by the things you do have control over. Over watering, under watering, not enough light, and more. These mistakes are very common, and not something to feel bad about!

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Here are some of the more common issues that gardeners run into, and what may have caused them.

1. Seeds fail to germinate

Possible causes:

  • Temperature of the soil is too hot or too cold. Most seeds like a soil temperature of around 65°-75°. In general, the warmer the temperature, the faster the seed will germinate.

  • Seeds rotting in the soil means it was too wet. Your soil should be moist, but not soaked.

  • Planting depth of the seeds – plant too deeply, and light is unable to reach the seed. Plant too shallow, and too much light can damage the seed. Most seed packets wil instruct you on how deep to plant your seed!

  • Growing medium was allowed to dry out. Your soil should remain moistened but not drenched, and not bone dry.

  • ‘Damping off’ disease, which can affect the seeds before they germinate. Damping off occurs when a pathogen that thrives on too-wet conditions is able to grow and kill the seeds before they can emerge.

  • Improper light (some seeds require light or darkness to germinate)

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A healthy tray of seedlings!

2. Seedlings fall over or start to decay at soil level

This is a sign of damping off disease (fungus organisms that attacks seeds and young seedlings, ultimately killing them). Some causes of damping off are:

  • Cold, wet soil
  • Poor soil drainage
  • Poor air circulation
  • Excessive moisture, over watering.If the soil remains consistently wet, it can rot the roots and prevent the seedling from taking in water. It may look like your seed needs water, but in actuality it needs anything but! Make sure to test the moisture of your soil by feeling with your fingers. Soil should be moist but not soaked.
  • Unsterilized soil mix, or reusing soil from previous seed starting
  • Dirty growing containers
  • Stress from low light

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3. Leaves start to curl under, growth appears stunted or dwarfed

Causes:

  • Too much light. Seedlings need a ‘rest’ period, which is why it is suggested to only provide 14-16 hours of light.
  • Over or under fertilization. Too little nutrients can stunt growth, too much much nutrition can damage the roots and prevent the seedling from taking in water.
  • Low temperatures. Most seeds like a soil temperature of around 65°-75°.
  • Excessive moisture and over watering. If the soil remains consistently wet, it can rot the roots and prevent the seed from taking in water. It may look like your seed needs water, but in actuality it needs anything but! Make sure to test the moisture of your soil by feeling with your fingers. Soil should be moist but not soaked.

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4. Seedlings have pale, discolored leaves; or leggy, spindly growth

Possible causes:

  • Insufficient lighting, or light source too far from your seedlings

  • Fertilizer burn from adding too much fertilizer, which can damage plants root system

  • Excessive watering

  • Nutrient deficiency – check the growing medium you are using to find out if nutrients are supplied in the mix. Some have tiny amounts to just get seedlings going, which means you then have to supply the rest until planted out in the garden.

  • Overcrowding of seedlings. Be sure to thin your seedlings to prevent this.

  • Temperatures too high.  Most seeds like a soil temperature of around 65°-75°.

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5. When transplanting you see poorly developed root systems

Possible causes:

  • Poor drainage

  • Low soil fertility

  • Damage from fertilizer salts, a.k.a. ‘fertilizer burn’, by adding too much fertilizer

  • Low soil temperatures. Most seeds like a soil temperature of around 65°-75°.

  • Compacted soil (lack of air space in growing medium), which can arise from over watering and poor drainage.

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6. Moss or mold is growing on your medium

Possible Causes:

  • Lack of air circulation. Set a fan up to move air around your plants

  • Excessive moisture. If the soil remains consistently wet, it can rot the roots and prevent the seed from taking in water. It may look like your seed needs water, but in actuality it needs anything but! Make sure to test the moisture of your soil by feeling with your fingers. Soil should be moist but not soaked.

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Here’s a short message of encouragement from our master gardener, Jaci!:

“As a gardener, I know how it can be discouraging it can be when some seedlings fail or don’t look perfect. Try not to dwell on it too long; just take the opportunity to gain some knowledge on the possible underlying causes so you can be successful in the seasons ahead. I have been gardening for nearly 20 years, and each year still brings new learning experiences for me.”

Some quick tips for making sure your seedlings flourish!

  • Once your seedlings have 2-3 sets of leaves, the most important thing to do at this point is to supplement them with nutrients! Most seed starting mixes very little nutrition, if any at all. We suggest using ¼ to ½ strength liquid fish/seaweed fertilizer every other watering for your seedlings to be at their happiest!
  • Using a soilless seed starting mix to start seeds is very important. Soilless seed starting mix is light, fluffy, and perfect for your seedlings to grow strong, sturdy roots! Garden soil or potting soil is often far too heavy and lacking in drainage, making it hard on the delicate root systems of the young seedlings.

What are your favorite tips and tricks for seed starting? Share in the comments section!

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4 thoughts on “What’s Wrong with My Seedlings? – Pinetree Garden Seeds

  1. I find the most important things for young seedlings are: sanitation sanitation sanitation! New or very clean containers and fresh soil less potting mix!
    Good light.
    Good air circulation.
    Weak fertilizer once the plants have a few sets of true leaves

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