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I always think that growing plants from seed feels like printing money. By investing just a little time and effort in sowing some low-cost seeds, you’re rewarded with a valuable abundance of fresh vegetables and vibrant flowers. But when those seeds fail to germinate, the time, effort, and money you’ve invested disappear down the drain. And yes, we’ve all been there!
Starting plants from seed can be one of the most rewarding parts of gardening, but when they don’t germinate as expected, it can leave you feeling frustrated and wondering what went wrong. It’s vital to remember that many seed varieties have a bit of a Goldilocks complex – if the conditions aren’t perfect, they’ll just sit in the soil and sulk. Fortunately, understanding the reasons behind failed germination can help you turn things around.
Let’s take a look at the most common reasons seeds fail to germinate, along with some practical solutions to help you get successful growth in the future.
1. Temperature Too Hot Or Cold
Every seed variety has a specific temperature range for optimum germination rates. If the soil is too hot or too cold, they may not sprout. Luckily, there’s a quick fix for this problem – by taking a moment to investigate the ideal temperature for each type of seed you are sowing, you can make sure to provide the perfect conditions for them to germinate.
For example, peppers and chilies love warm soil, so they benefit from a heat mat or propagator to boost germination. Spinach, radish, and lettuce all prefer cooler temperatures and are best sown in a sheltered outdoor location.
2. Incorrect Moisture Levels
Along with getting the perfect temperature, moisture is one of the biggest factors that affects germination rates in plants. Seeds need to be kept consistently moist but not soaked – if the soil is too dry, the seed will desiccate; too wet, the seed will rot.
To ensure the soil moisture levels are just right, use a seed tray with drainage holes and regularly check how moist the soil is. If the surface starts to dry out, use a gentle spray bottle to keep the soil consistently moist but not soggy.
3. Inadequate Air Circulation
Our third common issue with seed germination is poor air circulation – insufficient airflow can lead to mold growth or low oxygen levels. Getting the balance just right can be tricky, as increasing ventilation can cause fluctuations in temperature and loss of precious moisture. Ventilation also has a huge impact on humidity levels, particularly in heated propagators.
4. Poor Seed Quality
Seeds that are old, damaged, or haven’t been stored correctly can often fail to germinate. Often they look completely fine, but will not sprout no matter what you do.
This happened to me recently, when I sowed several varieties of chili seeds – despite them all having the same conditions in the heated propagator, two of the older seed types failed to germinate at all. Make sure to store your seeds in a cool, dry place and check their viability through a germination test before planting.
5. Insufficient Light
Most seed varieties are not too fussy when it comes to light, but some, such as lettuce and petunias will fail to germinate if kept in complete darkness. In contrast, other seed varieties, including beans and pansies, prefer to germinate in complete darkness. It is important to remember that as soon as any seed germinates, it needs as much light as possible to prevent the seedling from becoming leggy.
6. Planting Too Deep
Seedlings are delicate little things and are unable to push through to the soil surface if planted too deep. Make sure to always follow the recommended planting depth for each type of seed – this information is normally noted on the seed packet.
7. Incorrect Soil Type
One of the best investments you can make is to buy a sack of good quality seed compost to create the ideal conditions for optimum germination. Use this compost in seed trays and modules, and add a thin layer to the soil when sowing seeds directly in the ground.
8. Too Much Fertilizer
Did you know that a seed contains all the nutrients it needs to germinate and grow into a small seedling? Seed compost is deliberately low in nutrients, as over-fertilizing can burn seeds and hinder germination. Avoid adding extra fertilizer until your seedlings are large enough to be transplanted.
9. Pests or Disease
Sometimes external factors out of your control, such as pests or diseases, can prevent germination. A common pest issue in my vegetable plot is ants, who carry away every single carrot seed I ever sow! Fungal infections can also reduce germination rates, particularly in warm, humid weather conditions.
10. Not Enough Time
If you’re sure you’ve done everything right and your seeds haven’t germinated, it pays to have a little patience! Some seeds, such as parsley and lavender, can take several weeks to spring into life. If you’re not sure whether your seeds should have sprouted by now, research what their normal germination time should be.
11. Natural Dormancy
Nature is a very clever thing, as some seeds need a specific condition, such as cold or moisture, to break dormancy. This ensures that they germinate at exactly the right time to maximize their chances of survival.
Gardeners can mimic these requirements by soaking the seeds, scarifying them with sandpaper, or even popping them into the refrigerator.
12. Chemical Contaminants
Herbicides, pesticides, or chemicals in the soil can harm seeds and inhibit germination. If you suspect chemicals are the issue, plant new seeds in clean, untreated soil.
13. Water Quality
Tap water is not always the best choice for seeds, as chlorine or other contaminants can inhibit germination. If possible, use rainwater or filter water to water your seed trays.
14. Overcrowding
We’ve all been tempted to sow a few extra seeds, but this can actually be counterproductive! Planting too many seeds in a small space creates competition for resources, leading to weak or unsuccessful germination.
So, no matter how tempted you are, space seeds properly according to the instructions on the seed packet.
15. Seed Type Mismatch
If all else fails, you might just have to face the fact that the seeds you are trying to germinate simply aren’t suited for your climate, soil, or growing zone.
This happened to me when I moved from a cold, damp climate to a much warmer, drier one – after several failed attempts, I realized that some of my seed collection would never thrive in my new location.
A sad lesson to learn, but worth bearing in mind if you just can’t get your seeds to germinate!
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Kate Chalmers
Kate is a passionate gardener who has a keen interest in all things related to homesteading and sustainability. She resides in Portugal with her husband and menagerie of animals and has over 15 years of experience in the UK veterinary industry. In 2020, Kate and her husband took on a dilapidated Portuguese house and abandoned olive grove, turning it into an abundant food forest and home for nature.
Life on the homestead is never the same from one day to the next, and Kate has mastered many skills that she is keen to pass on to anyone with an interest in becoming more self-sufficient. Kate believes that living a sustainable lifestyle is the key to happiness and fulfillment and that everyone can make simple changes that connect us back to nature and reduce our impact on the planet.
