How do you know if the seeds are going to germinate?

If you are one of those who enjoys sowing seeds, you probably like to know in advance how many will germinate, right? It would be very good to know for sure, but unfortunately that, today, is impossible. But … (there is always a but) yes that you can do a few things to get more or less an idea of ​​how many will do it.

And no, you will not have to buy anything in the nurseries, because I am almost sure that everything you will need you already have at home.

Table of Contents

  • 1 Seed viability test
  • 2 What seeds are good for: those that float or those that sink?
    • 2.1 What to do if none of them sinks?
      • 2.1.1 Thermal shock
      • 2.1.2 Scarification
      • 2.1.3 Stratification
    • 2.2 What seeds cannot be germinated?
  • 3 How long does it take for a seed to germinate?

Seed viability test

Sunflower seeds germinate very fast

To know if the seeds are viable, that is, if they have the possibility of germinating, the fastest way is doing it in the following way: fill a glass with water -preferably transparent glass-, take the seeds and put them inside.

In a few minutes or sometimes 24 hours, you will see that there are some that sink and others that will remain on the surface.

What seeds are good for: those that float or those that sink?

What are the ones that will serve you? The ones that sink. A seed that remains floating is usually because it has not completed its development correctly, which means that there may be nothing inside, or on the contrary, there may be an embryo that has not completed its development.

In either of these two cases, the weight of this seed is slightly less than that of one that is viable. This difference, although it is really invaluable, is enough for one to remain floating and the other to sink.

What to do if none of them sinks?

There are some species that produce seeds that are tough, leathery, so sometimes even if they are viable there is no way they will sink. Therefore, if this happens to you, you will have to resort to other techniques, which are the following:

Thermal shock

It is a method that consists of put the seeds in boiling water for a second and 24 hours in another glass with water at room temperature. It is the most recommended method for trees such as Albizia, Acacia, Adansonia, Cercis, and for all those who have hard and oval seeds.


Delonix regia seeds

Seeds of Delonix direction (flamboyant)

It is a pregerminative treatment that consists of pass sandpaper to the seeds, until it changes color. It is widely used for the Delonix direction for example. After scarifying them, put them in the glass of water for 24 hours.


It can be natural, planting them in a seedbed and letting nature take its course; or artificial. Within the artificial stratification we distinguish two:

  • Cold stratification: is one in which the seeds are exposed to low temperatures (about 6-7ºC) for 2-3 months. To do this, they are sown in a tupperware with a substrate, such as previously moistened vermiculite, and placed in the refrigerator. The plants that germinate well this way are the vast majority of trees from temperate climates, such as maples, ash trees, oaks, holly, redwoods, etc.
  • Warm stratification: It is just the opposite: the seeds are put somewhere, like a thermos with hot water, to give them heat. Normally, they are kept there for no more than a day. This method is not used much, but for example baobab seeds sprout quite well after a day in hot water (around 35ºC).

Seeds sown in tupperware

What seeds cannot be germinated?

It may happen that, despite having subjected them to some pre-germination treatment, such as the ones we have mentioned (heat shock, scarification), they do not germinate. How can we know? What are those seeds that it is better to discard from the first moment?

Well, basically these are:

  • Those that have little holes: they can be made by insects, or by other larger animals depending on the size of the seed.
  • If you suspect they have fungus: if they are very, very soft, and / or if they are covered by a white or grayish spot, they will not germinate.
  • The seeds are old: we are talking about seeds that may have dwarfed, that are very dry and look like they have been thirsty. To know better, tell you that the smaller a seed is, the faster it has to be sown before they become “old.”

How long does it take for a seed to germinate?

The seeds are viable if they sink

It depends a lot on these factors:

  • Sowing time: In general, spring is the time when germination is most likely to occur.
  • Seed viability: if it is harvested directly from the plant as soon as it has finished maturing, it is most likely that it will germinate before an older one.
  • Plant type and species: In principle, herb seeds germinate much faster than tree seeds. In addition, within each type there are species that do it before others. For example: a palm tree seed washingtonia It only takes a few days to sprout, but it can take two to three months for the Parajubaea palm.
  • Weather: this also depends on the climatological needs of each plant species. Thus, those that come from humid tropical climates will only germinate during late spring in Europe; the vast majority of cacti and succulents, on the other hand, can be sown in summer as they require heat to sprout.
    On the contrary, the species found in cold climates are sown in winter so that they germinate in spring; in fact, they often have to be stratified to achieve an interesting germination rate.
Sempervivum are plants that can be transplanted in winter and sown in spring

If we take all this into account, below we will tell you a series of plants and how long they usually take to germinate as long as their seeds are fresh and viable:

  • Trees and shrubs: from one week to several months. On average, they require a month, but as I say, there are some that take a long time, such as conifers (redwood, yew trees, cypress trees).
  • Flores: pansies, geraniums, cyclamen, calendula, etc. All of them take about 7 to 15 days.
  • OrchardGarden plants are herbaceous, and often annual, so they germinate quickly, in a matter of a week at most.
  • Palms: from one week to six months. The most common (Washingtonia, Phoenix dactyliferaPhoenix canariensisChamaerops humilis) they need a few days to germinate; instead Parajubaea, Butia, Syagrus, etc. minimum two months.
  • Succulents (cacti and succulents): about a week, but it can be a month. Thus, the Ariocarpus and Copiapoa for example are very slow, but the Ferocactus or the Sempervivum take little time.

And then… to sow!

How do you know if the seeds are going to germinate?

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