Fall is the time to divide your bulbs. Dividing not only increases the number of your bulbs but rejuvenates the plantings. Crowded bulbs are competing for water and nutrients and will not flower with the abandon of bulbs that are divided every three or four years.
There are exceptions to this rule; crocus and daffodils can be left for many years without dividing and only need to be divided when the flowering decreases.There are a number of ways of dividing bulbs. Many bulbs will produce bulblets off the main bulb. Daffodils divide this way. You simply need to dig the clump up, shake off the dirt and pull the bulbs apart. Try not to destroy too many roots and make sure each bulb has some roots or at least a piece of the basal plate from which the roots grow. If small bulblets come off easily remove them. If they are firmly attached or have no root system leave them on the parent bulb to mature further. Bulbs divided this way can generally go directly back into the ground.Some plants such as fritillaries produce bulblets from the parent bulb or from underground portions of the stem. Lilies form bulblets but also form bulbils as do alliums. Bulbils form in the leaf axils and in the flower heads. You will often see them in the tops of onion plants. In “walking onions” or Egyptian onions they plant themselves. These smallest of bulbs rarely survive if they are not removed from the parent plant. They usually are ready to remove in late summer or early fall. Carefully peel them off when they come away easily. They cannot go back into the ground, as can the parent plant, but must be nurtured carefully in a specially prepared nursery bed. Dig and enrich the soil in a protected area and plant the tiny bulbs 2-3 inches deep and 6 inches apart. Get them in the ground quickly so they do not dry out and water them thoroughly. Corms are not true bulbs but are the swollen stem base where nutrients are stored. The plant roots are at the base and the growth stem is at the top. Corms produce small cormels. You will see them on gladioli and peacock lilies. The parent corm will die each year but during the season it will have produced a new corm and a number of cormels. In hardy species the corms may go back into the ground and the separated cormels will need to go into a nursery bed similar to the ones needed for bulblets and bulbils. The cormels of non-hardy species may be stored in a cool place and planted in a nursery bed in the spring. Before storing the top growth, roots and withered corm should be removed from the new corm. The cormels should also be removed. Both corms and cormels should be dried and dusted with a fungicide before storing. Bulbs such as lilies that produce scales can be propagated from the scales. Dig up the bulb and remove several of the thickest healthiest looking scales making sure that some of the roots or at least a bit of the root plate remains on each scale. This should be done right after the plant flowers so that there will be plenty of time to allow for the next steps. Replant the parent bulb quickly before it has a chance to dry out. Take the scales and rinse them off. Air dry them on newspaper and apply a fungicide. Prepare a flat of vermiculite or sterile potting medium and plant each scale to half of its height. Put the flat in a plastic bag with a few holes for ventilation and keep at about 70 degrees. In about six weeks the scales will have begun to turn brown but tiny rooted bulbs should have formed at the base. These can be removed and planted in a prepared nursery bed using the same technique that is used for bulblets. Bulbs such as daffodil and tulips are called tunicate bulbs. They consist of concentric rings of tissue. These bulbs may be multiplied by slicing them from top to bottom. This should be done in late summer or early fall. Dig the bulbs and remove the tops and clinging soil. Using a sterile knife slice the bulb vertically in half. These halves can be divided again and more slices may be made as long as each piece has a portion of the root plate included. They should then be handled as in a similar fashion as the scales. They will form rooted bulblets in 6-8 weeks. The bulblets should go into a sheltered nursery bed and, as they mature, into their permanent location. It will take several years for bulblets to bloom.Squill and hyacinths are also tunicate bulbs but they are best propagated by techniques known as scoring and scooping. This can be done on bulbs that are dug from the ground or on freshly bought bulbs. To score a bulb make 3 one half inch deep, intersecting cuts across the basal plate of the bulb. To scoop cut out the entire basal plate. This should be done with a knife sterilized in a solution of 1 part bleach to 9 parts water. Dry the bulb on a rack for 24 hours. The scored bulb will split open. Dust with fungicide and place the bulb on dry vermiculite or other sterile medium and keep it at 65-70 degrees for two weeks. They must be kept dry or the callus that protects the bulb will not form. After the callus has formed mist the trays lightly and place in a dark humid area at 85 degrees for 6-8 weed. New bulblets should have formed in the cuts by then. When they are ¼ to ½ inch in size; remove them and handle them using the previously described procedure for bulblets. Bulbs are often very expensive. Scaling, slicing, scoring and scooping are not that difficult and will greatly increase your supply of unusual bulbs in just a few years. When you buy bulbs that are unusual save one or two to propagate for stock. New techniques are always interesting to try and if they result in more plants your garden will be the lovelier for your efforts.