Gardening can be a big adventure, especially when it's a new skill. It brings unexpected delights and successes, but sometimes frustrations and even bewilderment. But don't worry! It happens to us, too. When it comes to gardening from seed, we are here to demystify common germination issues, so you can keep racking up those successes!
Starting with quality seed is the first step toward success. At Botanical Interests, quality is very important to us, and we know it is to you, too! Our seeds are tested frequently using a third-party laboratory to ensure germination rates exceed federal, and our own, standards.
We also include "days to emerge" on the back of the packet in the plant tag area to give you an idea of how long to expect seedlings to take to emerge if conditions are ideal. If conditions are acceptable but not ideal, you can expect delays; for instance, if you sow peas in cool soil, they may take several weeks rather than 5 to 10 days.
If you've begun with fresh, quality seeds and you still aren't achieving good germination, we look to the environmental factors that seeds depend on to troubleshoot the issue.
Clean containers and sterile seed-starting medium are essential to preventing pests and disease when starting seeds indoors. In an indoor setting, if one pest or disease is present, it can rapidly multiply with no competition.
While a sterile environment is impossible when sowing outdoors, nature has its checks and balances so that one pest or disease doesn't run rampant; it usually has predators and competition. Always remove and dispose of diseased plant material from the garden (do not compost it) to prevent the disease from spreading, and rotate plant families into different planting areas annually to help lower the potential for disease and pest issues.
- Seeds can fail to germinate due to pests or disease.
Soil temperature is a key component to getting good germination. Let's just clarify, soil temperature and air temperature are not the same thing. Soil has water in it and this combination causes it to stay cooler than the air, especially in spring as things are warming up. When conditions are cooler than ideal, germination may be prevented or very slow.
We include ideal soil temperature ranges on the back of every herb and vegetable seed packet and on flower packets that have ranges outside of average household temperatures. A soil thermometer is a handy tool when it comes to sowing seeds.
When starting seeds indoors, the seeds starting mix is probably pretty close to the temperature of the room it is in; but if that is too cool, you can use a seed-starting heating mat.
Ideal soil temperature also varies between species; and the time it takes to germinate, even in the right conditions, can vary even between cultivars. For example, sweet peas germinate best with an ideal soil temperature of 55°–65°F, while peppers germinate best with soil temperatures from 70°–90°F, but some extra-spicy peppers are known to naturally take longer to germinate. Read more about soil temperature and seeds in our article, Soil Temperature for Higher Germination.
- Seeds can fail to germinate when soil temperature is not ideal.
Growing Medium and Moisture
Seeds need moisture to germinate, but they also need oxygen, so conditions should not be soggy. Make sure your containers have drainage to prevent soggy conditions. A good seed-starting medium will hold the optimum amount of moisture, whereas some potting "soils/mixes" are designed to hold a lot of water to reduce how often you need to water. Seeds don't have the same water storing trick that plants do, and getting too dry isn't something they can recover from; aim to keep seeds consistently moist.
- Seeds can fail if they dry out or if they are too wet.
- Cool soil and wet conditions can cause seeds to rot, and if you look for the seed it may soft or decayed and gone.
Sowing seeds too deeply can cause them to run out of their energy stores before the emerging seedlings reach the soil surface and can begin making food through photosynthesis. Sowing too shallowly can make managing moisture more difficult, as the top of the soil or seed-starting medium dries out quickly. It isn't too common, but in some cases, darkness, or in other cases, light, aids germination, so following the seed packet instructions for sowing depth is important.
- Sowing seeds at the wrong depth can cause them to fail.
Most seeds are viable for 3 to 5 years if stored in a cool (refrigeration is not necessary), dry place, but as living things, over time they will eventually die and fail to germinate. Likewise, storing seeds in hot, humid conditions will speed their demise. There are some exceptions to this 3- to 5-year rule; some examples are edamame, lettuce, leeks, onions, parsnips, and salvia, which expire more quickly, so fresh seeds should be used annually for best results.
- Seeds can fail to germinate if they are not stored properly.
- Seeds can fail if they are too old to be viable.
In some cases, seeds also need some extra cues to help them germinate like exposure to light or winter-like conditions in order to break their dormancy. Any special germination instructions will be noted on the back of your Botanical Interests seed packet, right under the sowing instructions.
- Seeds with special germination needs can fail or have low germination if their requirements are not met.
Troubleshooting Germination Issues
- Nothing germinated. This is a sign that an environmental growing condition was amiss or seeds were old or not stored properly.
- Some seed germinated. If these seeds are all the same species, the natural time seedlings take to emerge may just be erratic; but if you wait a week or so and there is still no progress, this too can point to old seeds, having been stored in less than ideal conditions, or a special sowing requirement (see back of packet) was not met. If you are seeing some species sprout but not others, check your seed packets, as they are probably on different timelines or require different conditions.
- Seeds rotted. This points to too much moisture or a combination of moisture and cool soil temperature.
- Seeds are gone! They might have rotted beyond recognition, or been stolen by wildlife.
You've got this and you've got our support! We have lots of articles and blogs to help you through and you can always contact us with questions or concerns. Our goal is to help you grow flourishing gardens by providing high-quality seeds along with inspiration and education to get you growing strong!