Being the sort of person that I am, I sometimes gloat about the daffodils poking up in my Vancouver garden to friends and family, who are shovelling snow back East. Besides wondering about the pettiness of my own character, I wonder what makes daffodils come up when they do.
What's in a Name?
Daffodil is the common name for flowers of the genus Narcissus, like the guy in Greek mythology who stared at his own reflection for so long that he turned into a flower. I know that European colonists brought daffodils to North America, but I'm not sure where all our narcissism has come from.
Daffodils usually spend winter as bulbs—a kind of suspended animation, which helps them survive in places with harsh environments. Onion and garlic are also bulbs, but daffodil bulbs are not edible. Even deer and squirrels don't like them, probably because of toxic alkaloids like lycorine and galantamine. Sometimes people mistake daffodils for onions and get sick.
Like an onion, a daffodil bulb has a bud in the centre, surrounded by white, meaty leaves called scales, which provide food for the bulb to flower. Bulbs have a thin outer skin called the tunic. A basal plate anchors the scales and the floral stalk, with roots coming out the bottom.
If you want daffodils in the spring, you are supposed to plant the bulbs in late summer or fall, to a depth of two to three times the height of the bulb. Some people force the blooming of daffodils by manipulating conditions indoors. Even so, the bulbs still require a cool period, a cold period, and then a warm period. Flowers of the genus Narcissus come in many different varieties, with different peculiarities with respect to temperature and duration of these phases. Vancouver is in the hardiness zone 8b, which seems to be almost like forcing the daffodils to bloom early.
Cooler (below 13°C), moist conditions wake up a dormant bulb and it starts to grow roots. The bulb begins to break down starches into glucose and other small molecules which mix with water to act as an antifreeze by lowering the freezing point. This takes several weeks. If they don't have enough time to prepare before the first frost, the cells can freeze, so when spring comes, the bulbs will just be mush.
The daffodil bulbs not only prepare for the cold, they require it—about 13 weeks at less than 2 to 4°C.
The bulbs will begin to form shoots once the temperature reaches about 17°C. The timing of the bulbs can vary from year to year, not just because of the conditions of the spring, but also during the formation of the bulbs in the previous year. Sometimes the plants get fooled, if gets warm too soon. It seems that they stop growing if it gets cold again, but the shoots seem pretty tough and can survive through a bit of snow.
Sometimes just the leaves come up without blooms. This can be result of a fly larva. After daffodils bloom, the leaves produce food to recharge the bulb for next spring and form the next flower bud. Daffodils can be left alone to grow year after year. Just keep in mind that they may bloom later the year after their first bloom.
I found many sites dealing with the practicalities of planting bulbs, but I wasn't able to find more information on how temperature causes these changes in the cells within the bulb. So I will just have to enjoy the wonder of them showing up and keep wondering what is going on down there. Please let me know if you dig anything up.