1. Your seeds never germinate
Germination problems can be caused by a variety of reasons. Some of the most common are:
Incorrect Temperature. Different seeds have different needs. Cool weather crops such as cabbage, kale or broccoli have a much lower germination temperature while warm weather crops like tomatoes will germinate better with temperatures in the 70F range. If you are sprouting your seeds in a cool basement or outbuilding you may need to provide supplemental heat- such as a heating mat– to ensure germination.
Old Seeds. When properly stored seeds can have a very long shelf life. But the older they get, your germination rate will begin to reduce. For the longest life, store your seeds in a cold, dry place. Humidity and warmth will greatly reduce your seeds’ shelf life.
Incorrect Watering. Water in a necessity for all plants. In the germination stage you need to make sure you keep the soil evenly moist. If you water too much, you run the risk of your seeds rotting before they germinate. If you let them dry out, they will either never germinate or die trying!
Planting Depth/Light. When you plant your seeds pay attention to your planting depth. This is important because if planted too deep you plants could run out of energy before reaching sunlight. Planting too shallow can lead to drying out. Some seeds actually need some light to germinate, so instead of digging them down you just press them into your soil. Read your seed packets for information on each seed.
2. Your seeds sprout and then die
Everything starts off good. Your seeds germinate and you have little seedlings growing strong. Then all of a sudden they whither up and die! This is often called “dampening off”. It can be prevented by using these seed starting practices:
Do not over water. Too much moisture allows disease to grow and plants to mold. Once your seeds have germinated, water your seedlings only when the soil is beginning to dry out. Watering from the bottom is best, but do not allow them to sit in standing water once they are done taking it in.
Do not overcrowd. Your plants need room to breathe. A room with good airflow, as well as enough space between the plants will help them stay healthy.
Start with clean soil. Oftentimes disease in seedlings is caused by disease that is laying dormant in your soil or in your seed starting pots. Wash your seed pots and trays each year before planting. Consider buying a sterile soil if you have a major problem, that is not cured by the already mentioned steps.
3. It all started off good, but my seedlings just aren’t getting very big!
They sprouted, they are alive, but they just aren’t growing!! Just like with germination, different seeds have different needs. But here are some of the common reasons for stunted growth in your seedlings:
Incorrect temperature. If it is very cold your seedlings will not grow at the same rate they would in warm weather. Warm weather crops like peppers, tomatoes, or eggplant require temperatures around 75F to be happy. Even if they are small chances are when it warms up and they are outdoors they will take off and make up for their slow start.
Nutrient deficiencies. If you seed starting medium is lacking in nutrients they will not grow properly. Keep an eye out for the symptoms of some common soil nutrient deficiencies and feed your plants a little bit as they grow.
Overwatering. Over watering is the number one cause of stunted growth. If your seedlings are stunted and have yellow tips, this is most likely the cause. Waterlogged soil prevents the plant’s roots from bringing in oxygen, which will damage the roots and the seedling will be at risk for many more problems. Let the soil dry out just a bit before watering- and the soil should be moist not soaked.
4. My seedlings are tall, thin, and leggy!
Legginess is a common problem in plants that are started indoors and it is caused by the seedlings having to compete and stretch for their light source. Here are a couple of ways to reduce the tall, leggy appearance of your seedlings:
Rotate your trays. If you are using a south facing window, make sure to rotate your plants a couple of times a day so that all plants have an equal time closest to the window. Even if you are using an artificial grow light, rotating the plants within your trays is still a good idea so that all get equal time directly under the light.
Take advantage of warm, sunny days. If you have a warm day, set your seedlings outside in a protected area for a few hours. They will benefit from the direct sunlight, as well as get a head start on the hardening off process.
Use a grow light in addition to your sunny window to ensure the optimum daylight length of 15-18 hours.
Thin out your seedlings. The more crowded they are, the more they will have to compete for light.