Weed Seeds In Soil

Weed seeds can survive in the soil for years before they germinate and grow. This soil germination method is a low risk, easy method that that take up to 3-10 days. Read our guide to learn how to germinate seeds in 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.

How long do weed seeds survive in the soil?

CORVALLIS – Weed seeds can survive in the soil for years before they germinate and grow, according to Jed Colquhoun, weed specialist with the Oregon State University Extension Service.

Why should home gardeners care?

“If you combine the longevity of seeds in the soil with the fact that weeds such as common lambsquarters can produce over 500,000 seeds per plant, the incentive to hand weed your garden becomes much greater,” said Colquhoun.

“Prevention is the most effective form of weed control,” he said.

Here are some basics on weed seed biology:

Undisturbed weed seeds tend to persist longer than seeds subjected to periodic tillage. Weed seeds in deeply worked soil tend to last longer than seeds in shallowly worked soil. Seeds deep in the soil are “stored” below the germination zone.

Grass seeds tend to be less persistent than broadleaf weed seeds.

The number of surviving seeds of most weed species declines rapidly the first year. But thereafter the rate of weed seed decline slows. Some seeds can persist for decades.

As many as 130 million seeds per plow acre were found in a Minnesota study.

Different species of weeds have seeds that last varying numbers of years in the soil. The scientific literature provides some information about seed longevity, including:

  • Brome grass seed seldom lasts more than two years.
  • Annual ryegrass – up to nine years.
  • Perennial ryegrass – up to three years.
  • Annual bluegrass – up to about five years.
  • Wild oats – three to six years, but longer in deep soil.
  • Jointed goatgrass – three to five-and-a-half years.
  • Barnyardgrass – up to 13 years.
  • Quackgrass – up to four years.
  • Common velvetgrass – 10 years or more.
  • Mustards – are long lived. Seeds excavated from a monastery in Denmark were dated to be 600 years old and 11 of them germinated. More commonly, mustard seeds last for decades.
  • Lambsquarters – may last up to four decades.
  • Russian thistle (tumbleweed) – short lived, most live only a year.
  • Wild carrot – several years.
  • Curly dock – more than a decade.
  • Canada thistle – more than two decades.
  • Field bindweed – more than 50 years.
  • Leafy spurge – at least a few years.
  • Common groundsel – most die within a year.

Scientists found lotus seeds in Manchuria that germinated after over 1,000 years, said Colquhoun.

Soil Germination Method in 8 steps

Amongst the best ways to germinate cannabis seeds, this soil germination method is a low risk, easy method that explains how to germinate your seeds in soil. Germination can take 3-10 days, depending on environmental conditions and variety

Never use soil from your backyard! It can contain pests and moulds that will damage or destroy your seeds, seedlings or plants.

How to germinate seeds in soil

Read here which 8 steps you have to take for this soil germination method.

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Step 1: Prepare your soil

Prepare your pots with clean fresh soil. It is often easy to use small pots for this, and transport them to a larger container later.

Step 2: Watering the soil

Make sure your soil is wet, but do not soak it. It needs to be damp but not soaked, otherwise you risk your seeds to rot. In most countries, normal tap water is clean enough to use. Do not add any additives to the water.

Step 3: Placing the seed inside the soil

Make a small dimple in the soil and place the seed 3-5mm deep inside the soil. Don’t bury your seed too deep! When you put your seed too deep inside the soil, it will struggle to reach the surface, and have a high risk of dying before it does.

Step 4: Cover the seed and press gently

Cover the seed with soil and press the soil gently.

Step 5: Cover the pots with kitchen foil

Cover your pot(s) with kitchen foil or microwave foil (with the small holes). The foil will act like a small greenhouse, keeping the inside of your pot warm and moist. Perfect for germination.

Step 6: Poke some holes

When you use normal kitchen foil, poke some holes through the foil. This will avoid the risk of overheating and let air flow true.

Place your setup in a room with stable temperature. 20-25 degrees is ideal. We often advice your living room

Step 7: Wait for germination

All you have to do now is wait. In our experience it often takes about 4-5 days for your seedlings to show. But to calculate for differences in conditions and seeds, we say 3-10 days is a safe estimate. As soon as your seedling has sprouted (first leaves reach the surface) you can remove the foil.

Step 8: Take care of your seedlings

All 5 seeds germinated in 4 days within 24 hours of each other. You can now place them under a grow light, behind your window or outside (during spring / summer of course).

WARNING! Do not place this germination setup outside in direct sunlight, especially during summer. Day and night temperatures vary too much and sunlight will cause the temperature inside your soil to rise to a point where your seed will be damaged or killed by the heat.

17 Comments . Leave new

buongiorno dutch passion ho seguito il vostro tutorial e dopo 4 giorni la germinazione è avvenuta.una domanda vorrei fare,devo aspettare che si aprono i cotiledoni prima di rimuovere la pellicola o posso mettere il vas gia al sole anche se non sono aperti i cotiledoni. grazie e buona domenica

tutto ok germinazione perfeta.

When a seedling is in its first days its best to not place it in direct sunlight. This can be too much for a little seedling. When the seedling starts growing a little bit you can place it in direct sunlight

ok perfect I do this because I saw that it is the best method.I had put it in direct sunlight and it was dying, I managed to save it in time.I have one in germination and I will apply your advice.thank you very much Joe

Once the stem has come through the soil how long till you put it on a larger pot and up the tempreture

It depends a little bit on the pot size you started with.
Additionally, if you grow an autoflower its best to germinate them in the pot they will also flower in. They don’t like to be transplanted a lot.
If you grow feminised seeds than you can put them in a larger pot after 3/4 weeks.

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Greetings,
Joe
Dutch Passion

Sweet thank you ,

Hi, Joe answering?? I did an error putting seeds in soil not enough wet and under lamp … I choose Orange punch feminized and autoflowering…Is a good choice for me ad a beginner or could you give me best options? (Medium-high THC and quantity of final result) I also need some good ideas about the soil to use and the power of led lamps (I’ve buyed 2x100watt multiple ranges led lamp for plant grown for about 60cm x 40cm for 4/6 seeds). I have to do another order and I’m trying to do all well. Waiting hopefully for your answer, my best regards, thanks. Heathcliff

Critical Orange Punch is a good strain to start your growing career. Please try to follow the germination steps from this blog and you should be fine Don’t start your light if the seeds have not germinated yet. For your soil I advice you to have a type of soil that has minimum nutrients because seedlings cannot handle too much nutrients, these should be added later :).

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.

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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.