Why Plants Get Confused Between Spring and Fall

Q. I have daffodils and Dutch iris bulbs shooting out new flowers this last November. Each year they produce leaves in the fall but never flowers. Are they confusing this time of year with spring?  What should I do?

A. This type of oddity, flowering at the wrong time of year, happens with some plants. Sometimes we see it in fruit trees like apples or pears and even grapes. Plants are more in tune to their environment than animals and these environmental clues can sometimes mislead them.

            Plants that originate from temperate climates, climates with seasons, use two major environmental “triggers” to gauge when to flower and produce fruit. These two environmental triggers are cool or cold temperatures and unbroken darkness for long periods. This works great in the spring.

            A primary mission of plants is to survive and produce offspring. Producing flowers will produce fruit that produces seed. Spring flowering, not fall flowering, is extremely important for temperate plants. Flowering in the fall does not give most plants enough time to produce the seed needed for reproduction.

            If one or both triggers are activated at the wrong time the plant may be “tricked” into thinking it’s spring. Every fall the length of nighttime mimics the length of nighttime in the spring. That’s one trigger. If there are unusually cold temperatures in the fall, then both triggers could activate flowering.

What to do? 

Remove the flowers when you see them. Otherwise, leave the plant alone. Flowering in the fall is not a big deal but fall fruit and seed production is a huge drain on plant food supplies needed for next spring.