Temperature and humidity
For good germination, palm seeds need prolonged exposure to high temperatures and high humidity. The high temperatures can be achieved with the help of a greenhouse, heating cables or simply a closed sheet metal shelter that the sun will heat up quickly during the day. For high humidity, water the substrate containing the seeds, as well as the surrounding parts.
The time of exposure to heat varies depending on the species cultivated, but as a general rule it takes between 1 and 8 weeks for the seeds to emerge. Temperatures act cumulatively; fluctuations, such as nighttime refreshments, are not detrimental and do not cancel out the effect of high temperatures during the day. (The use of a heated greenhouse thus makes it possible to maintain a high temperature for 24 hours and therefore greatly reduces the time of germination.)
Moisture is essential for the germination of palm seeds. Pre-soaking the seeds reduces the period of exposure to high temperatures. The seeds will simply be immersed in a container filled with water at room temperature in your home for 24 to 72 hours. It is best to change this water every day in order to eliminate any inhibitors.
Seeds sown in good garden soil usually germinate without difficulty and develop quickly. However, soils often contain organisms that cause disease, weed growth and pests. Also, the use of substrate strictly reserved for sowing is sometimes safer, especially if the quantities to be sown are important. Horticulturalists use a variety of materials, coarse sand, peat, coconut potting soil, vermiculite, pine bark and sawdust.
Usually obtained from alluvial deposits. It should be washed thoroughly to remove impurities and weed seeds. It provides excellent drainage, but dries quickly after watering.
Organic material which has reached a stable state of decomposition. It is very acidic (ph – 4.5), sterile and absorbs several times its volume of water. It is an aerated substrate that mixes well with other substrates. It can be used as is for the germination of palm seeds.
Coconut potting soil
Natural organic material obtained during the harvest of coconuts and used in many forms around the world for its ecological qualities. It is an airy substrate that retains moisture very well. It mixes well with other materials but is very often used on its own for the germination of all varieties of exotic seeds or other species native to your habitat.
Natural mica which has been expanded by exposure to temperatures above 1000°C. It is a very light, well-ventilated material with a high water retention capacity. It mixes well with other materials but should not be overwatered or compacted as it becomes mushy. It is sterile given the high temperatures reached during its manufacture.
Finely ground pine bark, sometimes called pine peat because of its similarity in appearance and properties to peat. When fresh, it contains toxins and should be stored in moisture for six to eight weeks before use. It is better to mix it with coarse sand or vermiculite.
Like pine bark, fresh sawdust contains toxins, so it should be stored moist in a pile for six to eight weeks before use. It mixes well with sand or vermiculite and has good water retention as well as good air permeability.
The seeds of palm trees should be covered with a layer of substrate 1 to 3 centimeters thick or, more generally, at least the same thickness as the seeds. The sowing can be dense; quickly potted after germination, the seedlings will not have to suffer from the neighborhood.
The seedling containers should be deep enough as the roots appear first and sink quickly before the leaves emerge above the surface. Individual pots are ideal, but deep containers are also suitable, especially for large quantities.
For rapid germination, the ideal is to sow the seeds in planters, pots or trays and cover them with a plastic bag and keep at a high temperature. Using a heated greenhouse, mini seedling greenhouse simplifies this DIY.
Other techniques exist such as the sachet technique or the bottom heat technique which we will describe below.
This is to germinate the seeds in a plastic bag and not in a terrine or a pot.
The seeds are perfectly mixed with peat or coconut-based potting soil and enclosed in a sturdy plastic bag closed with a tie. The sachet is placed in a shady, warm and sheltered place. The seeds germinate and the seedlings are then transplanted according to their development.
This technique is useful for obtaining a large number of young plants because it requires little space. Young seedlings can be easily handled without damaging the roots. However, it should not be left locked too long otherwise they are too tight and end up withering. This technique allows a more regular emergence of the seeds.
The sachet can be transparent or opaque but resistant. Excessive UV exposure sometimes causes rapid plastic wear and tear in the pouch, which can result in rapid drying of the substrate and seeds. For the same reason, the bag must be closed properly.
Some palms species germinate more slowly than others and sporadically. Within a batch, seeds may germinate several weeks apart.
It is possible to accelerate the germination of such seeds by placing them in a multiplication box heated from below and maintained at constant temperature and humidity. The bottom heat is ideally set between 25 and 28°C.
The seeds mixed with peat moss or moist coconut potting soil and placed over a heating cable. Cover exposed seeds with a layer of moist substrate and water daily.
Subsequently, the seedlings are dug up and transplanted. This technique gives excellent results with species so the emergence is uneven.