Agave Propagation From Seed.
Agave seeds are black in colour and flat. They vary in size depending on the size of the parent plant. The percentage germination will be better and faster if the seeds are fresh. I have found that some seed sources are more reliable than others and it's not uncommon to get zero germination from small packet of 5 seeds.
The compost mix for sowing agave seed needs to be well aerated, maintain moisture and be free draining. The most important feature of the mix is that it should be free of pests and preferably sterile. There are products available commercially to prevent damping off diseases, just follow the instructons on the tin if you choose to use them. I have used chestnut compound for a number of years but this will no longer be an approved product under the Control of Pesticides Regulations 1986 with a last date for use of November 2011. Commercial seed compost can be amended by adding up to 50% potting grit or coarse sand to improve drainage and aeration.
The compost can be placed in seed trays or small pots and the seeds can be sown onto the surface and spaced about 30mm apart. The seeds should then be covered with about a 2 mm layer of compost. Agave seedlings sometimes fall over as they emerge so I usually add a layer of horticultural sand or fine grit to just cover the surface and provide some anchorage.
After watering the seeds they can be placed in a covered propagator to maintain a humid environment. For small pots, they can be placed in a polythene food bag to retain moisture. Place the trays or pots where they will receive sunlight but avoid cooking them in bright sunlight. If the seedlings take on a reddish tint due to anthocyanin formation as they emerge then they are getting more light than they would like.
Agave seeds germinate from within a few days up to a couple of months. As soon as a few seedlings have emerged any covering should be removed to avoid damping off disease.
Because agaves are monocots, when the seeds germinate they produce a single leaf that usually has a round stem tapering to a point with the seed coat perched on top. The size of the emergent seedlings will vary depending on the size of the original seed.
Agave seedlings shaded from direct sunlight.
After a few weeks the first leaf will split at the bottom and the second leaf will emerge. This leaf will resemble a normal leaf. Some time later, the third leaf will emerge and the seedling will start to take on the appearance of its parents.
Agave Triangularis seedling looking more like its parents.
Agave Chazaroi seedlings.
Agave Cupreata seedlings, note the split at the base of the first leaf.
After about a month, I usually start adding about a quarter strength balanced liquid feed at least once a month when I water the pots. Once the plants are big enough to handle I transfer them to individual pots. If they were sown spaced apart they could remain in the seed trays until the next spring. It all depends on how tangled up I think the roots will become.