The fate of weed seeds in the soil has been an area of much research in recent years. Most studies have focused on the seeds that successfully produce seedlings since these are the seeds that cause immediate problems for farmers. In most studies, annual emergence typically accounts for 1 to 30% of the weed seed in the soil. Thus, the majority of seeds found in the soil seed bank fail to produce seedlings in any given year. Cannabis growers often save seeds for a long time in order to preserve the original genetic of a particular strain that has worked well for them. If properly stored, a… Sometimes hemp seeds don't germinate because they are lifeless. Here's how to recognize a hemp seed if alive or dead to avoid wasting time. Read more here!
Fate of weed seeds in the soil
The fate of weed seeds in the soil has been an area of much research in recent years. Most studies have focused on the seeds that successfully produce seedlings since these are the seeds that cause immediate problems for farmers. In most studies, annual emergence typically accounts for 1 to 30% of the weed seed in the soil. Thus, the majority of seeds found in the soil seed bank fail to produce seedlings in any given year. The fate of seeds that fail to germinate and emerge is poorly understood. While some of these seeds are simply dormant and will remain viable until the following year, others are lost due to decay or consumed by insects or small animals. This article will describe results of an experiment that monitored the fate of seeds for the first four years following introduction into the soil.
Methods: Seeds of velvetleaf, waterhemp, woolly cupgrass and giant foxtail were harvested from mature plants during the 1994 growing season. The seeds were cleaned and counted and then buried in the upper two inches of soil on October 21, 1994. Two thousand seeds were buried within a 3 sq ft frame to allow recovery during the course of the experiment. Weed emergence was determined by counting seedlings weekly during the growing season. Emerged seedlings were pulled by hand after counting. In the fall of each year one quarter of the soil within a frame was excavated and the remaining seeds were extracted and counted. Corn or soybeans were planted between the frames during the course of the experiment to simulate agronomic conditions.
Results: The emergence patterns of the four species were described in an earlier article (see emergence patterns). The fate of the seeds (emergence, loss or survival in soil) during the first four years after burial is shown in Figure 1. In the first year following burial waterhemp had the lowest emergence (5%) whereas greatest emergence was seen with woolly cupgrass (40%). Total emergence over the four years ranged from 300 seedlings (15% of seed) for waterhemp to 1020 seedlings (51%) for woolly cupgrass. More than three times as many seedlings emerged in the first year than in subsequent years for velvetleaf, woolly cupgrass and giant foxtail, whereas 140 waterhemp seedlings emerged in 1996 compared to only 100 in 1995.
Figure 1. Fate of seeds during the four years following burial in the upper two inches of soil. Two thousand seeds of each species were buried in the fall of 1994. The area in white represents the number of intact seeds present in the fall of each year, green represents the total number of seeds that produced seedlings during the four years, and the blue represents the total number of seeds lost. Buhler and Hartzler, 1999, USDA/ARS and ISU, Ames, IA.
Seeds of the two grass species were shorter lived than those of velvetleaf or waterhemp. At the end of the third year (1997) no grass seeds were recovered. Somewhat surprising is that waterhemp seed was more persistent than velvetleaf in this study. Velvetleaf has long been used as the example of a weed with long-lived seeds. In the fourth year of the study four times more waterhemp seedlings than velvetleaf emerged and four times more waterhemp seed than velvetleaf seed (240 vs 60) remained in the seed bank.
For all species except woolly cupgrass the majority of seeds were unaccounted for (the blue portion of the graph) in this experiment. Determining the fate of the ‘lost’ seeds is a difficult task. A seed basically is a storage organ of high energy compounds, thus they are a favorite food source of insects and other organisms. In natural settings more than 50% of seeds are consumed by animals. The importance of seed predation in agricultural fields is poorly understood, but recent studies have shown that predation can be a significant source of seed loss. Another important mechanism of seed loss likely is fatal germination. This occurs when a seed initiates germination but the seedling is killed before it becomes established. Fatal germination probably is more important with small-seeded weeds such as waterhemp and lambsquarters than with large-seeded weeds, but is poorly understood. A better understanding of the factors that influence seed losses might allow these processes to be manipulated in order to increase seed losses.
So what does this mean as far as managing weeds in Iowa. First, consider how the methods used in this experiment might influence the results. The seeds were buried in the upper two inches of soil, the zone most favorable for germination. Most long term studies investigating the persistence of seeds have buried the seeds at greater depths than used here in order to minimize germination. If the seeds were buried deeper one might expect less emergence and greater persistence since the seeds would be at a soil depth with less biological activity. If the seeds had been placed on the soil surface it is likely that there would be more predation, less emergence and shorter persistence.
The results indicate that the seed bank of giant foxtail and woolly cupgrass should be able to be depleted much quicker than that of the two broadleaves. Maintaining a high level of weed control for two years should greatly diminish populations of these weeds in future years and simplify weed management. Unfortunately, a single plant escaping control can produce more seed than was introduced to the soil in these experiments, thus the seed bank can be rapidly replenished any time weed control practices fail to provide complete control. Finally, over 50% of velvetleaf and waterhemp seed was lost in the first two years following burial. However, significant numbers of seed of these species remained four years after burial. This will make populations of these two species more stable over time than those of woolly cupgrass and giant foxtail.
Doug Buhler is a Research Agronomist at the National Soil Tilth Laboratory, USDA/ARS, Ames, IA.
How to Rescue and Germinate Old Cannabis Seeds
Saving cannabis seeds is a widely used method for preserving genetic varieties that one has particularly enjoyed or that worked very well when planted. Therefore, growers often store some seeds for many years.
However, over time seeds lose their germinating power. This means that, after a few years, when farmers prepare to plant them, they run into problems getting them to sprout. To prevent this from happening, and to once again enjoy that cannabis you found worth storing, there are a number of tricks.
The key: the storage conditions
First, you have won half the battle if you were careful with the original storage. Seeds must be kept in a cool, dry place. Therefore, the best option is to store them in refrigerators at a temperature between 6 and 8 degrees Celsius, and with relative humidity levels between 20% and 30%. And sheltered from light, of course.
For all this you will need an airtight container or canister, or an opaque plastic bottle in which, in addition to the seeds, you should place little pouches of silica gel, to reduce the moisture. With regards to the best place in your refrigerator, the crisper is a good choice, as it is a little warmer than the rest of the fridge. Also, one last tip: if you store several strains in different bottles, it is a good idea to label them, so that you won´t have to open them to see which is which when you decide to plant them.
Hydration to trigger germination
If you have only saved the seeds for a year and a half, they should not give you any problems. After this time period, even if you have stored them properly, germination may be more complicated because the older the seeds are, the harder their shells, so the water used to open them will take longer to penetrate them. Therefore, the first method to try to get the plant’s embryo to develop is to put your old seeds in a glass of water, with a few drops of hydrogen peroxide, for 24 hours. Hydrogen peroxide softens the shell and facilitates the water’s infiltration.
But you must be careful: the liquid must not be cold, but rather at a temperature of around 22° C. And you must keep the container away from major sources of light. During the 24 hours that the seeds are there you will have to keep a very close eye on them in order to remove them quickly if they open, so they don´t “drown.”
Because of this risk, there are growers who choose another way: germinating their seeds with the help of wet paper towels and dishes. If this method is chosen, you’ll have to grab a plate and place a soaked paper towel on it. After placing your cannabis seeds placed on top, with enough space between them, cover them with another damp paper towel. Although this method is widely used, some purist growers insist that you have to be very careful, because the towels used may contain chlorine and chemicals that could impede germination.
For those beginning with the glass of water, the second step would be to move the seeds, after 24 hours, to the wet paper towels. Germination normally takes between 48 and 72 hours, and, in the case of old seeds, can last up to 5 or 6 days, or even weeks. Therefore, transferring the seeds to wet paper gives you more peace of mind, as you are dealing with less water and, if they open, they will not quickly drown.
Other good choices for germination
There are growers who prefer their seeds to germinate directly in the soil. In this case, in addition to ensuring that you have light and well-nourished soil, you can choose to dilute 10 ml (a teaspoon) of fulvic acid per litre of water, and use it to water the site where you have planted the seed. Another option is to use slightly carbonated water, as the additional CO2 will help the liquid penetrate the seed, causing it to germinate. It is also possible to use enzymes or germination enhancers, designed to help seeds open and develop in those first stages.
Another good investment, which can be key in the case of old seeds, is Jiffy 7. This product is a compressed pill of dried peat that you need to soak for a few minutes. At this point it becomes a small sack of soil that is specially designed to facilitate germination, because it features the ideal structure, is sterilized, has all the necessary elements to nourish the seedlings during the first week, and is pH-neutral. Due to these characteristics it can be your best bet to get your older seeds to sprout.
Last resorts to save your seeds
If all else fails, there are still a few more aggressive tricks that should only be used when, after a few days, your seeds have failed to hatch and make their way into the world.
For example, you can scrape off the outer layer of the seed with a little sandpaper, creating micro-abrasions that should let some water in. So you don’t overdo it with this scraping we have a little trick: roll up a piece of very fine sandpaper, with the rough side on the interior, and secure it with tape. Place the seeds inside and cover the openings with your hands. Then just shake it for a couple of minutes and the sandpaper will do its job. Another more risky option is to use a knife to cut the seed transversely, ever so slightly, which will help the water penetrate the shell.
If these methods work and get your seeds to break, allowing the embryo of the cannabis plant to emerge, you will have achieved your goal. You’ll have to be very careful when handling them during the first few days, but after a week your old strain, preserved for years, should grow just like a younger seed and, after a few weeks, offer the same harvest you got from it before and so fondly remember.
Dinafem Seeds The Dinafem team comprises cannabis experts and growing specialists eager to share their knowledge and expertise with the entire cannabis community. Don’t hesitate to give us your feedback on our posts. We’ll be happy to answer your queries and, above all, to learn new tricks and techniques.
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How to tell if a seed is dead? Here are some tricks
Sometimes hemp seeds do not germinate because they are lifeless. Here’s how to spot a dead hemp seed and avoid wasting time
In previous articles, we have repeatedly stressed how the quality of cannabis seeds can make all the difference in achieving a healthy and productive plantation.
Poor quality seeds can lead to weak and unprofitable plants or even to no germination at all.
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This article will learn how to recognise quality hemp seeds (such as BSF seeds) and tell if a seed is dead and therefore totally useless.
Dead or bad hemp seed: here’s why quality is essential
In the field of hemp growing, some choose to buy ready-made seedlings, and those prefer to plant the marijuana seeds themselves so that they can monitor the growth of the plantation from the very beginning.
Of course, in order not to waste time, it is essential to make sure that you are dealing with quality seeds of the right genetics (such as auto-flowering seeds, feminised seeds, etc., which you can find for sale at SensorySeeds), but above all, they must be alive!
Yes, you got that right!
If the seeds are too old or have been stored incorrectly, they may have lost their ability to germinate, and so, even if you put your mind to it, the seedlings won’t grow.
In the next section, we will clarify the main signs that the seeds you have in your hands may be lifeless.
Dead seeds: how to recognise them?
Many novice cannabis growers are tempted to buy low-quality marijuana seeds because they are sold cheaply.
Up to this point, it all seems quite normal. However, in such cases, the problem is that the seedlings often do not grow, and it isn’t easy to understand the cause.
Many people wonder what they might have done wrong and try to figure out what to do if the seeds do not germinate.
Of course, sometimes you make mistakes, but you have to check whether the seeds you have bought are still alive in other cases.
Knowing how to distinguish high-quality seeds from bad ones is very important to avoid wasting time and money.
Let’s start with the appearance.
Good quality seeds usually have a kind of waxy layer that shines when exposed to light. As a result, their colour can vary from brown to grey or black, with some speckling.
If you are dealing with white or light green cannabis seeds, they are immature and unable to germinate.
Seeds that appear ‘dried out’, have cracks or dents are of poor quality.
You can also tell by touch whether the seeds are good or not.
If you hold a hemp seed between your index finger and thumb and apply pressure, some seeds crumble, while others do not at all. The quality ones and the ones most likely to be alive are, of course, the latter.
A test is considered almost foolproof to see if hemp seeds can germinate: water immersion.
If by putting them in a glass with warm water they float, then it means they are dead or rotten; whereas if they go down, they are of good quality.
Of course, all these tricks apply to seeds of all genetics and types.
If we have intrigued you, you too can try floating feminised seeds, fast seeds or auto-flowering seeds from your collection (but remember that growing cannabis is not allowed in the UK).
Concerning the flotation test, however, we would also like to point out that it should only be carried out during the hours before sowing and that the seeds must be removed from the water within 24 hours. Otherwise, they will be irreparably damaged.
Live seeds which do not germinate: what is the cause?
If also thanks to the advice given above, we know that our seeds are alive but still do not germinate, there is probably another cause.
Let’s see what the main ones might be.
- Soil which is too cold
- Sometimes it is the temperature of the soil that is too cold that prevents marijuana seeds from germinating. If you keep the soil warm enough, you will see faster germination.
- Incorrect choice of substrate
- It is usually recommended to use a relatively friable and light substrate when sowing cannabis. If the seedlings do not germinate, the root growth may be prevented by too loamy and difficult to penetrate.
- Sowing too deep
- Cannabis seeds, being relatively small, should be planted close to the surface of the soil. Otherwise, the sprouts will not be able to emerge.
- Insufficient irrigation
- Sometimes cannabis seeds fail to germinate because they are not watered enough.
- It is essential to keep the soil well moist, as this is the only way for the seeds to swell and germinate.
As we have seen, you can use a few tricks to find out if your cannabis seeds are dead or not.
Unfortunately, even if the seeds appear to be alive and of good quality, they may have genetic defects. That is why the best choice is always to buy quality fast flowering seeds (such as BSF seeds) at the outset.
After this in-depth analysis and always remembering that cultivating and consuming cannabis is forbidden in the UK, we invite you to consult the seed proposals in our SensorySeeds.com store.
Choose the products you prefer to complete your collection, take advantage of our advantageous prices and fast delivery.
We look forward to seeing you in our SensorySeeds online shop. See you soon!