Starting your own seedlings is a great way to save money in the garden and to select varieties that will work for your climate and food growing needs. However, starting seedlings is not always trouble-free! Here are a few common seed starting problems and suggestions on how to troubleshoot them so your seedlings look just as healthy and vigorous as ones from a plant nursery!
Common Seed Starting Problems
Dampening Off Disease
Dampening off is a disease caused by a combination of fungi and mold that can cause a variety of undesirable symptoms in seedlings, such as root rot, weakened stems, failed germination, and wilted leaves. Entire trays of plants can be affected, particularly in cool, wet conditions.
The most common symptom of dampening off disease my seedlings experience are thin, weak stems that look like they’ve been crushed. It is very difficult for seedlings to recover from dampening off disease, so the best way to troubleshoot is to prevent the disease. Common factors contributing to the disease are low light conditions, cool soil temperature, and overwatering. Try the following tips to prevent dampening off disease:
- Avoid reusing potting soil
- Sterilize pots and trays before the start of each season and after use
- Use grow lights or other techniques to ensure that your plants are getting between 12 and 16 hours of light per day
- Water with room temperature water rather than cold water
- Wait until soil temperature is optimal for seed germination
These kale seedlings were started without a grow light and later moved under the light. They are a bit on the leggy side, but have grown up nice and green!
Leggy Plants
Long, leggy plants are the result of insufficient light. Your seedlings need 12-18 hours of sunlight to thrive. If you notice that your seedlings are thin, tall, and spindly, one solution is to use an indoor grow light system that will deliver the right amount of light until your plants are ready to be moved outdoors.
Until this year, we had not found a grow light system that was compatible with our solar electric system. I developed a fairly effective system of starting seeds without electricity, but leggy starts were an ongoing problem.
This winter, I noticed that Gardener’s Supply launched a new suite of LED grow light systems, and I was instantly intrigued! Gardener’s sent me their Two-Tier Compact LED Grow Light system to try out*, along with a power strip with timer so I could easily set the light to turn on and off automatically.
What a difference! Even though we had a stretch of rainy and cloudy days, and I had to turn the grow lights on for only 3-4 hours a day, my seedlings have never looked better. They are robust, healthy, and deep green in color.
Mold Growth
If you notice some furry white growth on the surface of your soil, you may have mold growth. This is often caused by excessively damp soil conditions. You want your soil to be moist, but not wet. To prevent this, allow the soil surface to dry before watering and be sure to keep adequate ventilation around your seedlings.
Poor Germination
Another seed starting problem is poor germination. Because I have a rather large collection of seeds, this is the problem that I experience most frequently.
Are you using older seeds? A good way to determine seed viability before you even place them in soil is with a simple seed viability test. Your results may tell you that your seed germination rate is low, in which case you can sow multiple seeds per block, or simply sow more than you expect to plant.
Another cause of poor germination is incorrect soil temperature. Your seed catalog or packet should tell you the optimal soil temperature for germination. Some seeds, like peppers or eggplants, need a high temperature to germinate; they simply will not germinate in a 45 degree garage without a heat mat.
If you are starting seeds directly outdoors, you may also suspect birds and rodents. Be sure that you are starting seeds at the depth recommended by the seed packet and if seed thieves are a perpetual problem, consider covering your garden bed with a tight row cover or screen until germination occurs.
I hope you don’t have to deal with any of these common seed starting problems, but now you know how to recognize and troubleshoot them if you do!
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* I received the abovementioned LED grow light system and power strip with timer from Gardener’s Supply to test and write about my experiences (which have been extremely positive!!)
Many of my seed starts initially grow but seem to stall right before the first or second true leaves develop… they don’t die, but they don’t grow. I’ve completely reworked my lighting system, so they aren’t leggy, but they just don’t seem to grow. Any thoughts?
Hi Katt, without knowing more about your set up, a few things I would suggest to check are 1) your seed quality – are you using new seeds? Older seeds lose some vitality in storage. It can make a difference. 2) Does your growing medium have enough nutrients to support the growth of the seedlings when they develop their true leaves?
Hope that helps!
Thanks for the article, very good info. I usually take my chances when starting my seeds indoors but get so so results. This guide helps a lot.
I’m glad it was helpful! Thanks for reading!
Every time I try to start vegetable plants from seed I end up with long threads instead of normal plants, I have been told it’s too much water but I have watered according to directions and even less, I have had better luck just throwing seeds into the garden and letting nature take it’s course, what could be wrong? am I one of those who just cannot grow plants from seeds and is doomed to plant buying from nurseries? last year I bought 50 Roma tomato plants to end up with baby Roma’s, that would be all right if I wanted them but I ended up with a bumper crop and thousands upon thousands of baby Roma’s to make sauce for the year, I hate trusting someone else.
If you’re getting long threads, which I’m assuming means that you’re ending up with very thin, stringy, or leggy plants (on a long spindly stem), it’s likely due to inadequate light. That’s why the grow lights come in handy!