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marijuana seed float test

One cost-effective and simple trick to determine if your seeds are worth the time is to see if they float in water. Fill up a glass or jug with water and place your seeds on the surface. Leave your seeds in the water for a few hours and return to check on them later. Seeds that have sunk to the bottom of the water are healthy and should be germinated now that they have been soaked. Any seeds that remain floating on the surface are likely of bad quality and shouldn’t be used if you don’t want to risk wasting time.

So, you’ve obtained some seeds and plan on germinating them soon, but you’re a tad unsure about their quality. Well, the first port of call is to take a closer look at them. This can be done with the naked eye, but using a magnifying device makes things a lot easier.

Below are a few simple and easy methods you can use to assess the quality of your cannabis seeds.


The most reliable way to check if your seeds are viable is to simply place them in the soil and allow them to germinate. Although this method is easy, waiting for them to pierce through the top layer of soil can take some time. This can be especially time consuming when growing on a large or commercial scale, or when simply wanting to get a grow started as quickly as possible.

Before we even get around to testing the quality of our seeds, it’s important to discuss where to source them. By purchasing seeds from reputable dispensaries, seedshops, and headshops, you greatly enhance the chances of your cannabis seeds being of good quality. Additionally, you will have the knowledge of exactly what the strain is, its characteristics, flowering time, and so on.

There’s another box that needs to be ticked off the list before growing as well, one that is often overlooked. Checking the quality of your cannabis seeds before placing them in the soil is a simple process, and one that can save a lot of time and energy in the long-run.

If you have time to spare and are growing cannabis purely out of recreational joy, then you can simply go ahead and germinate the seeds. This is a 100% accurate way to determine whether a seed is viable or not.

Some smokers might be pleased to see some cannabis seeds in their bag, and might think themselves lucky. However, finding seeds in a bag is bad for various reasons. For one, this means the grower has messed up and allowed their female plants to be pollinated by an invading male. When flowers are pollinated, they stop producing THC-containing resin and divert their energy toward producing seeds. Secondly, the seeds will have added to the overall weight of the bag, which means less weed for your buck.

However, slight patience is required when conducting the float test, as results are not immediately apparent. You’ll have to wait for approximately 1–2 hours before confirming the results. Some good-quality seeds will need adequate time to absorb enough water for them to sink. Use this time to go water the garden and get some much needed pruning done. Upon your return, any seeds that remain on the surface are most likely not viable and won’t be worth further time and effort.

The one true method to test the genetic potential of a seed is to simply put it in the soil. It won’t take too long to see the results. This option is best for the hobby home grower who has time and space to spare for a risky project. Growers cultivating cannabis for commercial use likely don’t have the excess time to invest.

Germinating All Your Seeds Regardless

Unlike other agricultural crops (like vegetables, fruit, or grain), cannabis hasn’t undergone the vigorous breeding techniques that ensure a stable crop. This means that you’ll sometimes sow a pack of seeds technically labeled as the same “strain,” but may end up with very different looking plants. It also means that the individual seeds you buy from a seed bank can vary in appearance.

The alternative to this is to risk buying seeds from a hobbyist. This isn’t to say that hobby growers cannot produce fantastic genetics, but if you don’t know them or their skills, there’s no way to know whether your seeds will grow.

The color and feel of a seed, on the other hand, can tell you a little more about its maturity and, potential to germinate or grow into a healthy seedling.

Mature cannabis seeds usually have a hard outer shell that can vary in color from very dark (or almost black) to very light grey and may have tiger-like stripes. You should be able to firmly press these seeds between your fingers without damaging them.

These cannabis seeds were floated in 8oz white paper cups covered by a pot tray. These cups were then placed under a T5 light approximately 1ft away from the tops of the cups.

After a total of four days since the cannabis germination started a majority of the cannabis seedling should begin to sprout from the surface of the growing medium.

7pH in a container that is covered from direct light. When the tap root is about ¼ to ½ inch in length, you know the cannabis seeds are ready to be placed into their growing medium.

June 03, 2019

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Within 24 hours these seeds had a success rate of 100% with all seeds showing tap roots and being placed into a different set of 8oz paper cups that were full of presoaked promix. The promix was only immediately presoaked using filtered water with

In general, growing cannabis from seed can offer the opportunity for growers to possibly create something new which can be exciting and different. Besides genetics, phenotypes based on the grow environment can create different alterations of the same cannabis strain (Conviron, 2017). An individual can easily purchase seeds online or by pollinating and hybridizing one’s own seeds for use. Cannabis growers may find more success by first floating or soaking their cannabis seeds in filtered water, than planting directly into a growing medium.

The germination of cannabis seeds depends on the right amount of heat and moisture (NGA, 2018). Since viable cannabis seeds float on the surface of the water, they are able to retain the proper ratio of moisture and air. Seeds that do not float may be sterile or underdeveloped. When you roll the seed in your hands prior to floating the seed, it should be firm and brown with the occasional dark stripes in appearance. Immature cannabis seeds appear green or sometimes white and as stated above they will sink to the bottom when you attempt to float them.