Monday, 4 September 2017

Seed Preparation


By this method the seed coat is altered (damaged) to allow water to enter the germ and begin the germination process.  Particularly hard coated seeds will always benefit fromt this although the methods may vary according to the species.


1. Hot or boiling water treatment.  Cover the seeds in hot (85 Deg c) water and allow to cool.  For certain seeds (members of the pea family in particular) boiling water may be used, in this case barely cover the seeds with a small amount of boiling water and use a ceramic cup (it draws the excess heat away from the seeds after a while allowing the boiling water to briefly do what it needs to do to soften the coat without 'cooking' the seeds.

2. Soak in a solution of saltpetre.  Make up a weak solution of saltpetre (5g per litre of warm water) and soak the seeds in this.  Particularly beneficial for Bananas, Gingers and Strelitzias as well as pines and many other fibrous coated seeds such as some of the palm family.

3. Mechanical abrasion. Using a fine grade of sandpaper, an emery board or file, rub the seed until it changes colour at the point of abrasion to indicate that you are through the outer layer.

Use one of the above (never more than one) and then proceed to the soaking phase.


Firstly two notes about this process -

1. Not all seeds need soaking, although all can be (perhaps the exception here is seeds that are very tiny)

2. If you do soak, not all bad seeds float and not all good seeds sink.  The age of the seeds may be a factor, but older seeds are not necessarily bad - Baobabs can germinate after 10 years, Pines after a similar period, some annuals can last 100's of years, Lotus several hundred and Phoenix (date palms) have germinated after being uncovered in Pharoahs tombs!  The thing is that there will always be imperfections in seeds and this may make them float - at least to start with.

The purpose of soaking is two fold, firstly to get water into the seed to kickstart the process of germination and secondly (and less widely known) many seeds have germination inhibitors (chemical compounds in the seed coat) which prevent or delay germination.

When soaking seeds, change the water regularly.

Every 12 hours for long soaks where there are no known inhibitors.

Every 8 hours where germination inhibitors are known or suspected.

Whenever there is considerable discolouration of the water.

Soak in luke warm water and try to maintain it at or just above room temperature.  We find that plastic or styrfoam cups are best for this process.  Make sure they are clean before you add the water and the seeds.  Stir or agitate to sink any seeds and then leave for the recommended time in the germination instructions, changing the water according to the schedule above.

Tiny, lightweight seeds can be 'soaked' by placing them on damp tissue or blotting paper, which is then folded in order to surround the seeds with moisture.

After the final soaking period, rinse the seeds thoroughly to remove all traces of fruit and debris, as these will only cause issues when planting (a point of entry for disease). 

All seeds have been shown to benefit from a warm water spray at this point.  To do this, get a mist sprayer (either a hand pump or pressure type), fill it with hot (60 Deg C) water and place the seeds in a seive or muslin and spray them for about 5 to 10 minutes.  This acts as a final clean and we have found that some seeds, especially those designed to be eaten and pass unharmed benefit from this and will germinate much faster than if not treated.

Finally if you forget to soak the seeds and find that they are not germinating, then try this.  Uncover the pot and water it regularly with a drench of water from the top.  What you are trying to simulate are Spring rains, so alternate soaking and slight drying over a period of days can have the same effect as a few days soaking in a cup of water.  The trick here is to flush out anything that can be naturally delaying germination - after all it rarely rains just once at the start of the growing season, so we are trying to fool the seeds into thinking they are naturally growing in the wild.


Stratification is the process of subjecting seeds to both cold and moist conditions. Typically, temperatures must be between 1°C and 5°C (34°F and 41°F). The purpose is to mimic the variations in temperature that occur in winter and spring in order to get the seeds to germinate. It can be carried out at any time of year, artificial stratification is most useful if trying to get seeds to grow outside of the normal period or where using nature is just not practicable.

In its most basic form, when the stratification process is controlled, the pretreatment amounts to nothing more than subjecting the seeds to storage in a cool (ideally +1° to +3°C; not freezing) and moist environment for a period found to be sufficient for the species in question. This period of time may vary from one to three months.

To accomplish this you merely place the seeds in a sealed plastic bag with moistened vermiculite (or sand or even a moistened paper towel) and refrigerate it. Use three times the amount of vermiculite as seeds. It is important to only slightly dampen the vermiculite, as excessive moisture can cause the seeds to grow mouldy in the bag.

After undergoing the recommended period of stratification, the seeds are ready to be removed and sown in the nursery bed for germination. Alternatively, the seed may be sown in small pots filled with moist soil and then the whole thing enclosed inside a plastic bag before placing inside a common refrigerator.

Any seeds that are indicated as needing a period of warm stratification followed by cold stratification should be subjected to the same measures, but the seeds should additionally be stratified in a warm area first, followed by the cold period in a refrigerator later. Warm stratification requires temperatures of 15-20°C (59-68°F). In many instances, warm stratification followed by cold stratification requirements can also be met by planting the seeds in summer in a mulched bed for expected germination the following spring. Some seeds may not germinate until the second spring.

Use of a fungicide to moisten your stratifying vermiculite will help prevent fungal diseases. Chinosol (8-hydroxyquinoline), primarily a disinfectant and often recommended for growing succulents from seed prone to mold, is one such fungicide, if this is not available, then a copper based fungicide or neem oil (both made up as directed) are excellent alternatives.

Different seeds should be placed in different bags rather than putting them all into one bag, and large quantities are also best split into several small bags. That way any fungal outbreak will be restricted to only some seeds. If no fungicide is used, a close check should be kept on the seeds, removing any which show signs of mould or become soft and with a decaying smell.

If an outbreak of fungus occurs, remove the seeds and re-apply fungicide, then place them in a new bag with new slightly moistened vermiculite. Always keep the bag sealed. The stratifying seeds should be checked on a regular basis for either fungus or germination. If any seeds germinate while in the refrigerator, they should be removed and sown immediately.

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