Five Common Mistakes Beginners Make When Growing Seeds (and How to Fix Them)
Growing seeds is a relatively simple process: stick the seeds in the ground, add water, heat and sunlight, and in most cases something will sprout. The problem is that most of us do this process internally because we are trying to speed up the growing season. Inside, where there is no sun, heat is difficult to control, and the most your seedlings can stretch out their new little root legs is the size of the plastic cell they are planted in. So it takes some practice to grow strong, resilient seedlings, and beginners make a lot of mistakes. The good news is that most of them are solvable.
Not enough light
This is one of the easiest problems to diagnose because it is also one of the most likely problems. Remember, when growing seeds inside, you should try to imitate the sun. When people estimate how much light they need to reproduce the sun, they almost always underestimate. It’s easy to explain: your seedlings will be “leggy” with long stems that are not strong enough to support the leaves of the plant. The stem is often twisted, almost like a plant with scoliosis. Seedlings may also lean towards the light.
The solution, of course, is to add more light. I’ve found that too often people new to planting buy one grow light to light an entire shelf of seedlings when each tray requires 2000-5000 lumens (that’s a lot of lumens). It’s not just how strong the light is, but also how long it’s on: seedlings require 14 to 16 hours of sunlight per day. These lights should also be much closer to your seedlings than you think. A suitable distance is six to eight inches above the seedlings.
If your seedlings are already too leggy, there are a few things you can try. First, if it’s tomatoes or peppers, you can bury the stem deep in the soil when you pot the seedlings or plant them outside, and this will solve a lot of problems. If they are a different type of seedling, such as a cucumber, they usually don’t need the same strong stems and will likely correct themselves over time. It will help to run a fan in the room and run your hands over the seedlings several times a day. Both will help strengthen the stems.
Too much light
With most plant diagnostics, it can be frustrating to hear, “It may be too much or too little.” This is not the case with light. It is very easy to determine if there is not enough, as above, or too much. Just like us, plants can get sunburned. Burns appear on them, and almost white or golden spots appear on the leaves at the top. The spots also have no pattern.
Seedlings are susceptible to a variety of diseases, fungi and viruses, so you may be wondering if it’s sunburn or something else. The good news is that it doesn’t matter because the solution is the same: cut it off. Sunburned leaves cannot absorb light and nutrients and cannot recover, so trim them back completely and allow the rest of the plant to recover. Obviously, move the light further, but don’t overdo it. Although seedlings can get close to traditional bulbs, my experience is that LED lights burn more easily, so while traditional bulb lights can be a few inches away from my seedlings with no problem, I keep LED lights six inches or more away.
No germination
Of all the seeds you plant, some will simply not germinate. There are many reasons for this, but let’s look at the most likely ones. First, you may have buried the seed too deep or not deep enough. The back of each seed packet contains instructions on how deep to plant the seeds, and this is not a vague recommendation. While the difference between a seed planted an inch or an inch and a half deep may not matter, there is a huge difference between seeds that need to be lightly covered (like carrots and most flowers) and those that are buried, like tomatoes, peppers, cucumbers and sunflowers. Another tip: the larger the seed, the deeper you bury it. Zinnia seeds are barely covered, but pea seeds need about an inch deep, and large bean seeds need to be buried deep in the soil.
Unfortunately, this is one of those problems that needs to be addressed upfront. If a seed sits in wet soil for too long and does not germinate, it has most likely rotted. You’ll just have to start over; by the time you realize the seed isn’t germinating, it will likely only be a few weeks since planting, so you won’t lose too much time.
Another reason could be that the seeds are simply out of date . Each type of seed has an expiration date. It can be very short, like an onion, which is good for a year. Experienced gardeners know that these are just guidelines; you can always test your seeds by trying to germinate them to make sure they are okay.
The seed rack you use to heat the seeds may also be too hot, causing them to cook. You want the seed and soil temperature to stay between 70-80°F, but no more. When the seeds are ready they will disappear, so start with fresh seeds.
Too much water
You can fall in love with your plants. Too much water, even if your plant survives, will prevent your seedlings from growing a strong root system. Underwatering is always the best solution if plants need enough to survive, as it forces the roots to reach out in search of more resources, creating a stronger root system. The most ideal methods for watering seedlings are those that allow them to consume as much water as they need, such as bottom watering, which leaves a little water in the tray to allow the soil to absorb moisture. But even if you water from above, the soil should be slightly moist, but never wet.
Yellowing leaves or soft plants are usually a sign of overwatering. If your plants start to smell bad, there is likely mold growing in the water, which is another sign that there is too much water. In such cases, the solution is to go the other way and use less water. Your plants may or may not recover. If you trim away any root rot or soft leaves and stems, it may recover.
However, most seedlings develop green or white fungus on the surface of the soil, and this is not necessarily a bad sign. This just happens and will not affect your seedling in any way.
Not enough water
Drooping seedlings usually need water. Tomatoes in particular will begin to lean over and literally look sad. This can happen towards the end of the watering cycle, and if you don’t let them fester, it’s not a problem, but it is a sign that they need to be watered. You should see the plants perk up immediately within an hour or two of watering.
If your soil block is really dry, it’s never a good sign. You want your soil to always be slightly moist, not dry. If you are having trouble maintaining soil moisture, you should consider bottom watering as mentioned above as it is a consistent method. The soil absorbs what it needs.