Growing snowdrops from seed is an interesting way of increasing your plants, as you are never quite sure what the outcome will be.
In order for the plant to produce seeds it has to be fertilised/pollinated, that is, pollen has to attach itself to the stigma. This process can either be left to happen by chance through insects and bees, or helped along by the use of a small brush.
When fertilisation has taken place the seed pod will start to swell to accommodate the growing seeds. The stem will gradually bend to allow the seed pod to come to rest on the ground, where it will ripen and split open spilling the seeds on to the open soil or removed by ants, which are attracted to the soft parts that are attached to the seeds.
To stop the loss of any seeds that I want to grow on, in mid-May I encase the seed pods in little muslin bags. Take a two-inch square piece of muslin, put the seed pod (which is still attached to the plant), in the centre of this, draw up the corners of the muslin and wrap cotton around the encased seed pod. Not too tight, just enough to hold it in position. If the seed pod now ripens before Iíve harvested it the seeds are held in the little bag. This also deters the ants from pinching the seeds. By mid-June I harvest the seed pods and put each variety into a greaseproof paper bag to ripen fully.
Ideally it is best to sow the seeds as soon as possible. Half fill a plant pot with whatever compost you would normally use (I use 50% peat based compost and 50% vermiculite), place seeds on to the compost then add enough compost to nearly fill the pot and firm down to ensure that the seeds are in contact with the compost. Water well and leave in a shaded cold frame or outside on a North facing wall. Keep just moist and preferably un-frozen in winter. The seedlings should appear in the following spring. Sometimes, for what ever reason, seeds may not germinate the following spring, but may do the next spring, or even the one after that.
Once germinated put the pots in a frost free greenhouse and keep just moist. Water the seedlings with a weak tomato food about once a month. Allow the bulbs to go dormant at the end of the season then re-pot into fresh compost and grow on for a second year under cover. After the following growing season they should be large enough to survive outside.
If you do not have the space or facilities to accommodate pots then the seeds can be sown straight into the open ground, in drills, approx two inches in depth.
Hybridisation can be fun and totally unpredictable. Like most things in nature an offspring will be 50% of each parent, but it is impossible to choose which 50% you want to keep and which 50% you want to discard. So it is with snowdrops. A plant with large flowers and a green inner mark crossed with a small flowered yellow one may not necessarily give you a large flowered yellow snowdrop you could equally get a small flowered snowdrop with green markings.
Choose which snowdrop you want to be the seed bearer (female parent) and pot up some bulbs in the autumn and grow on in a greenhouse/cold conservatory. When the flower has just opened and before the anthers have produced any pollen, remove the anthers with a pair of tweezers. Cover the plant if possible with a bell jar, to stop accidental pollination by stray insects. On a warm sunny day transfer the pollen from your selected pollen parent (male parent) onto the stigma of the female parent. Use a small brush, piece of foam or a pen top that you have rubbed on your clothing to create static electricity. It is best to repeat this process for a few days. Try to keep the plant covered at all times.
If fertilisation is successful the ovary will begin to swell. When the seeds are ripe sow them as normal.
Keeping notes about the snowdrops used in the hybridisation process and the results are paramount.
Remember not all snowdrops, especially hybrids, can bear seeds or produce fertile pollen.