"Four seeds you must sow, one for the rook, one for the crow, one for to die and one for to grow."
Many species are not available as bulbs, and even if they are, some countries restrict your ability to import bulbs. So raising bulbs from seed is the best way to both obtain and increase your bulb collection. The information found on this page is the shared recommendations of PBS forum members collected over the years.
There are two types of seeds: the dry seeds of many genera and the fleshy seeds of some amaryllids. The fleshy seeds need special handling (see below).
Seeds can be grown in any type of container, including recycled plastic or styrofoam drinking cups. A seedling mix, generally of 1:1 sand (or perlite) and peat based seedling mix tend to work well for most types of seed. Consult the individual species listings for details on the seeds you're growing. Some seeds need to be sown on the surface whereas others need to be covered up. Some require cold stratification to germinate, and others may need fluctuation between day and night temperatures. All seeds have a viability period which may last just a couple of months to many years, depending on how they are stored (dry cool storage is usually best).
The number of seeds sown per pot depends on the size of the pot, the size of the seeds, and how fast the bulbs grow. Michael Mace likes to sow about nine seeds per 18-ounce (500 ml) drinking cup. Sowing the seeds too close together may cause the seedlings to be overcrowded and in some species can cause damping off fungal disease. If your seedlings start to develop fungus (usually a gray hairy growth that causes them to wither and fell over), you need to teat them with a fungicide immediately or you'll probably lose the whole pot. The seeds will start sprouting within two weeks to three years, depending on the species and seed treatment. Usually winter-growing seeds will sprout within two months of when you start watering them in the fall.
Once the seeds have sprouted, keep them protected from extreme weather conditions, snails and slugs, and fungi. Grow the seedlings according to the species requirements. Many will go dormant the first year, but others may not. It is generally a good idea to fertilize the seedlings with a diluted high P low N fertilizer. This treatment works very well in some species (like Calochortus) but does not affect the growth rate in other species. When the bulbs go dormant (the leaves will turn yellow), stop watering and store the containers in a cool (but not frozen) dry place.
Some bulbs, such as many amaryllids, have permanent roots even when dormant, and will appreciate a little water even in the dry season.
Allow the seedlings to grow for at least two years before repotting the bulbs during their second dormancy. Disrupting the seedlings too soon can be detrimental to the plants.
This is the classic reference work on seed germination techniques. It's now out of print, but fortunately copies are available online.
Seed germination, theory and practice
First supplement to the second edition of Seed germination theory and practice
Second supplement to Seed germination theory and practice
A taxonomic index to the works of Norman C. Deno
UC Botanical Garden
Ontario Rock Garden society
Kew seed information database (contains germination data for many species)
Jane McGary's excellent article on how to grow bulbs from seeds (PDF) which originally appeared in a NARGS bulletin
David Griffiths' 1934 USDA publication 'Bulbs from seed'
Ian Young's article on the Scottish Rock Garden site entitled Bulbs from seed
PBS discussion thread on growing bulbs from seed
Breaking dormancy in seeds (how to make them grow when they refuse)
Seed collection methods (PBS forum discussion)
Raising bulbs from seeds in a hot dry climate
Flotation (floating seeds on water to help them sprout)
Karrikins and other growth regulators
Notes are added to wiki pages with links to those notes below. Many of the original notes were compiled by Mary Sue Ittner from bulb discussions forums. Other notes are added as information is provided.
by General Category
Amaryllids - All the fleshy amaryllids (including Amaryllis, Brunsvigia, Crinum, Boophone, Cybistetes, Nerine, Crossyne, Clivia, Gethyllis, Hessea, Strumaria plus a few others are ephemeral, or recalcitrant as they are more commonly known. The issue is not that the seeds do not last long, it is more that they cannot prevent the germination process, so will germinate even if conditions are inappropriate. The seeds ripen within days to a few weeks after the flowers have been pollinated, and the seeds then begin to germinate within days and produce a root first. The root sometimes develops while the seeds are still in the capsule (Rachel Saunders).
Once harvested, sow the seeds immediately onto the surface of a well drained mix (1:1 organic:inorganic) and water lightly. Ungerminated seeds should not be covered by the medium because they need light to germinate. If covering is necessary, a portion of the seed should be exposed to light. If you received material from overseas, most of the seeds will have sprouted by the time they arrive. Sow these immediately, using a pencil to make a hole which accommodates the radicle (root). If small leaves have started to sprout from the radicle, put the join between the leaf and radicle at ground level. The seed should always remain on or above the surface. Some seeds will only produce a tiny bulb in the first year, which then goes dormant; others will grow continuously for a couple of years. If the seeds keep growing, do not force them into dormancy.
If you live in the Northern Hemisphere and order amaryllid seeds from South Africa, they will arrive at exactly the wrong time for planting. You have two choices: plant them anyway, and do your best to keep the seedlings from dying in the heat of summer; or store them in the refrigerator in a sealed plastic bag. This can delay sprouting for a few months until the fall. Both approaches have risks, so if you have seed to spare it's a good idea to divide them into two lots and try both approaches (Michael Mace). Some growers have good luck sowing the seeds immediately and keep the plants growing in an air conditioned room under bright fluorescent light.
For special genera like Haemanthus, Scadoxus, and Clivia, the colorful fruit coat must be cleaned before sowing. Seeds sown without this treatment have poor germination.
Australian geophytes The seeds can then be soaked for 24 hrs in a 10% solution of liquid smoke solution (not the cooking type). With luck, you'll get germination in many of our more difficult taxa. A lot of the "lilies" are still recalcitrant after this (or even GA treatment) a combined smoke and temperature treatment may be necessary for many species. A useful treatment of smoke followed by cool and wet simulates the WA or southern Aussie winter rains when most of these taxa germinate (John Conran).
Oncocyclus Iris Seed may take up to about 5 years (some say 7 years) to break dormancy. Soak the seeds in hot water for few hours and stratify them in the fridge for a month or two before sowing. These seeds germinate very well in the first year and viability drops in subsequent years. I have observed that second, third and even fourth year seeds, if disturbed or "transplanted" to another pot, would improve germination (Dennis Tsang). The Oncocyclus specialists have developed some elaborate techniques of chipping and treatment with gibberellic acid. For more information, contact the Aril Society International.
South African (non amaryllids, winter growers) South African non amaryllid winter growers need a marked difference in day and night temperatures to get good germination. This is also true of many seeds from other mediterranean regions. So if you're growing in a greenhouse, you need to be sure it cools off at night. Some species require smoke treatment as well. I get the best germination with fresh seed (Marc Hachadourian).
In certain climates, sowing winter-growing bulbs in spring does work, although not as well as autumn sowing. However, the plants will be 6 months out of synch with their normal growing cycle. At this point, you can prevent the seedlings from going dormant through artificial means. Otherwise, allow them to grow for a season or two in their wrong cycle and adjust them to their normal cycle as if they were bulbs coming from the Southern Hemisphere (Ian Black).
South African Irids Seed viability - many of the Iridaceae, particularly those with hard coats, last for years, and we have sown 8 year old Dierama seed with excellent results (Rachel Saunders). Other PBS members have reported some success with Irid seeds that are a decade or more old. But you'll generally do better with fresh seed.
Barely a geophyte
Dodecatheon Sow the seeds and keep them about 4 °C (40 °F = refrigerator temperature) for 1 month, followed by warmer temperature. Some species will germinate without a cold period, but most require a short one. Since they are so small for quite a while and have fairly delicate roots, the safest bet is to sow them thinly into pots with clean and fast-draining soil and plan to keep them in the pots for a year. Shooting stars sometimes tend to germinate erratically and also can decide to "wait" a year, so keep the pots even if nothing happens this year and you may see results next year (Louise Parsons).
Lapageria rosea The seeds are easy to germinate and require no special treatment other than moisture and cool temperatures (~10-15 degrees C). The plants do not seem too fussy about potting mix, although something open and a bit acid seems to be preferred (John Conran).
Xerophyta Seeds can be very small sow sowing on the surface gives better results (Will Ashburner). Xerophyta viscosa germinates in 8 weeks when surface sown in spring. Winter sowing takes 18 weeks.