Sleeping seeds is the common terminology used for seeds that have a dormancy period of some sort. Most seeds, especially those of a perennial nature are especially prone to being sleeping seeds.
There are several reasons you may have seeds that never seem to germinate no matter what you try. It could be that the seeds may have harvested before the embryo or seed coat was fully developed rendering the seed non-viable. It could be harvested seed was not properly stored, again causing the seed to not germinate. Those cases are usually rare.
The main cause for seeds not germinating is seed dormancy. Seed dormancy is where the seed is alive and viable, but until it receives the favorable conditions it requires, it remains in a sleeping state, incapable of germinating. This ensures that over time and periods of environmental stress the species will survive. Now that may be fine for seeds trying to survive in nature, but it can be a heartbreaking experience for the gardener who just spent a small fortune on purchasing those 5 or 10 seeds that came in the package and not a single one has made a seedling or even attempted too.
There are some things you can try and do to wake up sleeping seeds. First research about your plant. Find out all the facts you can about it. Don’t just follow one sites advice either. Look at several sites in different areas for matching germination techniques that have been tried. Look for the answers to some of these items.
1. Moisture requirement. Does my soil need to be on the dry side, moist or soaking wet for germination? A seed develops an embryo and other metabolic activities, but once it makes a seed coat, all that activity stops. That seed contains just enough water to keep it alive and viable. It will not germinate until the proper amount of both water and oxygen has permeated the seed coat. For example, if the sites all agree that soaking for 24 hours is beneficial to breaking dormancy, than it is important to follow those directions. Don’t do 10 hours, or 30 hours, but 24 hours. Not enough of either water or oxygen, or too much cause drowning of the embryo and no germination will happen.
2. Light requirement. Do my seeds need light to germinate and how much? Look to see where your seed is native too. Does it come from a country that is nice and sunny most of the time? Some seeds require certain light levels whether started indoors in trays or by soil seedbanks. Light reflected from the sun is a different level intensity than that of moonlight. If your starting seed indoors using artificial lights, make sure that the candle light from them is adequate for germination. Turning your artificial lights on, running up the electric bill, does no good if the bulbs do not produce enough candle light wattage to germinate the seeds. ( Soil seedbank is another term for planting seeds outside in the ground, nature’s seedbank.)
Some seeds need darkness to germinate, but watch because as soon as germination is noticed, those seedlings need light to develop properly. Leaving them in the dark to long can cause another host of problems. Check too what is meant by darkness. Darkness for some seeds, means uncovered and no light at all. For other seeds it means, just a light covering of soil to hide the seed and being placed in a sunny spot to germinate.
3. Temperature. Some seeds like it hot and some like it cold. Check the recommended germination rates. If a range of temperatures is given, generally, most seeds prefer the lower temperatures. Generally, cool temperature between 10C and 15C allow oxygen to make its way into the seed while warm temperatures prevent oxygen uptake. Cooler temperatures can also soften the endosperm, area around which your radicle needs to emerge. Those folks who winter sow seeds can see this type of germinating from the cool melting snow upon their seeds.
Even if you give your seeds the proper amount of the above items mentioned, pampered them every way possible, your still going to have a percentage of seed that is not going to germinate. Blame it on the Mother Plant and her mothering of the seed. Just like us humans, not letting our children out into the world and releasing our influence over them until they mature or reach a certain age, so does the Mother Plant control her seeds babies even if they are scattered round to new environments.
She has also hidden other types of dormancy you may or may not know about. Those are usually found in the " after-ripening" period.
The seeds will grow and develop and be feed from the Mother plant. From genetic coding the Mother plant makes sure that as long as those seeds are in the pods and attached in some way to her that the seeds will not germinate. Genetic coding for germination inhibitors are also feed to the seed. Once the seed has fully developed and is released from the mother plant, a period of time is needed before full maternal control is given up. This time period is called the “after-ripening” period.
In a broad sense, after-ripening describes the loss of the dormant state in a seed over some period of time. In the strictest sense, after-ripening refers to the loss of dormancy mechanisms imposed by the Mother Plant.
Depending upon the species, seed maintained in dry storage or planted in the soil seedbank tend to lose this maternal control over dormancy and germination without any applied dormancy breaking methods over a period of days to years depending upon the species.
After-ripening is a period of metabolic inactivity that the seed must go through to finalize the separation from the Mother Plant and become independent and on its own. This is what we as gardeners want to see happen in a few days or weeks, not in years and what frustrates us the most.
The mother plant is pretty smart. Sometimes the mother plant will release her seeds with embryo’s that are not fully developed. This is another dormancy and germination type of protection. Without a fully developed embryo the seed will not germinate. Depending on the physiological and environmental conditions that particular species requires, it could take days, weeks or years for the embryo to fully develop. Seeds that are released with fully developed embryo develop rapidly and easily.
Too, in some cases of seed not germinating, it is because the mother plant has developed a special protective membrane around the radicle (the root) that does not allow the maximum uptake of water that the seed needs to grow and develop and break the radicle out of the seed coat to start growing. Seeds that are started in seedling trays where not enough moisture or humidity has been provided have a harder time overcoming this problem and may not germinate at all. Gardener’s who figured their seed trays are not going to germinate, threw them outside maybe on a compost pile where they received proper moisture amounts, later had seedlings popping up.
The mother plant also includes enzymes and hormones to prevent germination. These inhibitors can be found in different parts of the seed or the seed coat. Most of those inhibiting chemicals are dissolved over time with water, though if the inhibitor was coded in the embryo it usually is the right temperature that is needed to break up those inhibitors. The use of Gibberellic acid ( GA) can possibly help too for those really stubborn seeds.
Now if all the above is not enough for the mother plant to ensure her seeds will have the best start and chance of survival, as a last resort she may make sure those seeds are protected by a hard seed coat. Some of those seed coats are so thick and hard it would take many years for the seed to germinate in the wild. This seed coat is a physical barrier to the uptake of water for the embryo and usually takes some form of scarification to break it. Care must be taken that while trying to break through the seed coat you do not damage the internal seed.
It would be so nice to have every seed we get germinate and grow up into a beautiful seedling, but the reality of the situation is, it just isn’t going to happen. So before you spend a lot of money buying a few seeds that may or may not germinate, try finding somebody who is willing to trade or offering to share the seed you are looking for first. Don’t plant all the seeds at once. Do your research. Try different methods of germinating the seeds.
Most of all don’t give up hope if your seeds don’t germinate the first time round. Keep on trying and one day you may just discover your sleeping seeds have woken up and are on there way to becoming a beautiful plant.