8 Common Seed Starting Mistakes to Avoid — The Coeur d'Alene Coop (2024)
This post was updated on Feb.18, 2022.
Starting garden vegetables from seed is easy and cost effective – plus you’ll find pages upon pages of varieties and cultivars in catalogs and online! To ensure your seed starting is successful, avoid these 8 common seed starting mistakes.
Starting Seeds at the Wrong Time. Timing is everything when it comes to growing from seed. Whether you are starting indoors or direct sowing into the garden, it’s critical to know your region’s last average day of frost. For north Idaho it’s May 15th. Warm season crops should be started indoors 6 to 8 weeks before this date; cool season crops 4 to 6 weeks prior to the frost date.
For north Idaho that means tomatoes, eggplant, and peppers should be started indoors from mid-March to early April. If these are started from seed in late April or May, they may not have enough time to mature and produce fruit in the garden. Cool season crops, like spinach, peas, lettuces and greens, can also be started indoors and transplanted into the garden in mid-to-late April (usually 2 to 3 weeks before the last frost date).
2. Using Inferior Growing Medium. Whatever you do, don’t go cheap or skimp on your seed starting medium. This is the foundation for your plant stock. To get your seeds off to a good start, choose a quality soil-less seed starting mix. These are usually a mixture of peat, coconut fiber, and perlite. The consistency is very light and fluffy. Avoid potting soil mixes that contain bark pieces and/or fertilizer. Heavier potting mixes can deter germination and regarding fertilizer, well, nature packs seeds with all the nutrients they need to get started. And finally, never use soil from your garden – it’s too heavy, lacks proper drainage, and may contain disease or insect eggs that can affect your tender seedlings.
3. Starting seeds in cold, wet soil. Seeds need warmth to germinate. A few days before planting, bring the seed mix into the house and warm it up. If the mix is dry, this is also a good time to add a cup or two of water to lightly moisten the mix. You want it moist — not soppy! Let the mix come to the ambient temperature in your house before planting. Once seeds are planted, use a heat mat to help move germination along and aim to keep soil temperature in the 65 to 70 degree range. Once the seedlings emerge, remove them from the heat mat.
4. Planting Seeds Too Deep. One of the main reasons why seeds don’t germinate is because they were planted too deep into the soil. When planted too deep, seeds can “use up” all their energy trying to make it to, and break through, the soil surface. Check the depth recommendations on the seed packet and follow these! Many seeds can be placed on the soil surface and covered with a ¼ to ½ inch of fine seed starting mix. Some seeds need light to germinate and should be scattered on the surface and not covered at all. When I start seed (and I start a lot!), I dampen the soil in the growing container first, then place the seeds on the surface and spray the seeds with a fine mist of water from a spray bottle (warm water, of course!). Finally, I lightly cover the seeds with the seed starting mix and spritz the soil again. This ensures good seed-to-soil contact and helps soften the seed coat.
5. Not Labeling Growing Containers or Trays. Guilty! How many times have I done this? I’m not telling, but suffice it to say, it has happened more than once! It’s so easy to get confused – you’re excited to get growing and before you know it you’ve planted three kinds of seed and you don’t know which is which. Seeds of a variety look alike and so do the seedlings! Plan ahead…grab a Sharpie and a plant tag, wooden stick, or address label and tag those containers or trays!
6. Not Enough Light. Seedling need bright light to grow. In fact, they need about 12 to 16 hours of light per day. Your sunny window may not provide enough light to get them off to a good start. An inexpensive LED fluorescent shop light will provide all the light your plants need. Make this easy and put your light on a timer. For stocky and healthy plants, place the light about 3 inches above the seedlings. No more scraggly, leggy seedlings!
7. Too Much Water. This is probably the #1 mistake in seed starting. Keep your seedlings moist, not wet. Too much water causes a fungal condition known as dampening off – seedlings will rot at the soil level and die. Let the soil surface dry a bit – it’s much better to be a little dry than too wet. No baby wants a soggy bottom. If you are using grow trays without holes, add water to the tray and not at the soil surface. The water will be absorbed from the bottom up.
8. Not Giving Seedlings Enough Attention. And speaking of babies, that is exactly what seedlings are and need to be treated as such. Young plants, like young humans and animals, require attention. Check on your seedlings several times a day to monitor moisture, temperature, and any signs of distress, disease, or insect issues. If neglected, they won’t survive. Now we know why garden centers are called “nurseries!”
A two-part guide to seed starting can be found on our blog. Read Part 1 here. And you’ll find Part 2 here. Happy growing!!
The soil must be at least 50°F to start cool weather veggies (lettuce, spinach, peas), and we don't usually plant these seeds before late April. See the separate handout “Growing Vegetables in Northern Idaho.” If we have had a long, hot summer, soils stay warm until early December.
The soil must be at least 50°F to start cool weather veggies (lettuce, spinach, peas), and we don't usually plant these seeds before late April. See the separate handout “Growing Vegetables in Northern Idaho.” If we have had a long, hot summer, soils stay warm until early December.
Keep the fan running 24 hours a day. In addtion to helping prevent disease, the constant air movement will help develop stronger, sturdier seedlings. Plant your seeds in fresh soil that's formulated for seedstarting. Never re-use potting soil because it can carry disease.
Most seedlings require water every day or every other day. First, check the soil moisture using your finger by checking the soil color near the drainage hole. If the soil feels or appears dry or brittle, irrigate thoroughly until water pours out of the bottom of the tray, then stop.
Sow seeds early in the morning so the water has enough time to permeate the soil and get warm throughout the day. You can do it in the evening but make sure the seed flats stay warm overnight. Keep sown seeds away from direct sunlight and keep at a temperature of 75F-90F degrees—double check for specific seeds.
Early to mid-March is the best time to plant early season cold-tolerant plants like broccoli, cabbage, and head lettuce, and long-season heat-loving plants like peppers, okra, and eggplant. If you mainly just start tomatoes at home, you can wait until early April.
Moisture Matters – After planting, water seeds with a gentle mist or shower. Avoid using a strong splash or spray, which can dislodge seeds. It is vital to keep soil consistently moist. In a sunny spot, this may mean watering twice a day.
After seeds have sprouted, watering from above with any force is likely to knock over the fragile seedlings. This is why it's best to use a mister. With a mister or spray bottle, you have to be willing to check on your baby plants at 2x a day to make sure they don't dry out.
It is important to note that you should not plant seeds in a waterlogged mix or too dry of a mix. If you can wring a steady stream of water out of the mix, it's too wet and you'll need to add more dry mix. Many times, we consider the moisture level of our potting mix, but sometimes forget to consider soil temperature.
Seedlings need 14-16 hours of light every day. Make sure you don't leave them exposed to the light for 24 hours a day. They need rest from the light just like they would get in natural conditions. I recommend keeping your grow light on a timer so that it turns on and off at the same times each day.
The minimum amount of light is 10 hours. Generally, seedlings need 14 to 16 hours. You can get into the scientific amounts and test it down to the optimal hours and minutes - and some studies do just this. Keep a close eye and see if they seem to be stretching.
Humidity domes are meant to stay on the tray until the first sign of germination or once you begin to see the tray sprout. After this, remove the dome and place your trays under light, with proper air circulation. If brought under light too late, seedlings can get leggy.
However, they are very sensitive and susceptible to extreme temperatures, light, and heat. Therefore, a seedling must be acclimatized properly before transferring into the open field or in direct sunlight. Hence, it can be said that direct sunlight can kill or destroy seedlings and it is advisable to avoid doing it.
They may be bending forward rather than growing up straight with a strong stem. If your newly germinated seedlings look like this, it may be due to one of three common causes: Insufficient Light. This is the usual reason why leggy, tall thin seedlings develop.
The rule of thumb is to plant seeds at a depth equal to two or three times their width. It is better to plant seeds too shallow than too deep. Some seeds, such as certain Lettuces or Snapdragon, need light to germinate and should not be covered at all.
The best time to seed cool-season grasses in Idaho is late summer and fall for several reasons. Soil temperatures are optimum for seed germination, there is less competition from summer annual weeds, and the newly emerged grass seedlings will not be exposed to summer heat.
Spring is an ideal time for direct sowing many seeds, but some can be sown during summer and autumn. Check seed packets for the recommended times of when to sow outdoors.
Introduction: My name is Patricia Veum II, I am a vast, combative, smiling, famous, inexpensive, zealous, sparkling person who loves writing and wants to share my knowledge and understanding with you.
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