En Español

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
    
 
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
11 ratings

Wednesday - October 31, 2007

From: Harrisso twp., MI
Region: Midwest
Topic: General Botany
Title: Plants killed by frost
Answered by: Barbara Medford

QUESTION:

In a frost why do flowers etc. die where grass will not die?

ANSWER:

To quote from one of our favorite books, Botany for Gardeners, Revised Edition, by Brian Capon:

"In winter, when the leaves of deciduous species have fallen, water movement comes to a standstill in the plant. If the remaining water freezes in its cells, its expansion ruptures the delicate cell membranes-a condition from which there is no recovery."

Very generally speaking, plants die without water in their systems. In a quick frost, some of the top blooms or leaves might get brown or fall off, but if the water in the stems is not frozen hard, the plant itself will survive. A longer frost, a real freeze, can freeze that stem moisture to the point that the plant dies from dehydration, as well as the damage from expansion of remaining water, as cited above. Many plants, especially what you might refer to as "flowers", are annuals. They really are only programmed to live one season, bloom, make seeds after blooming, spread the seeds, and then their purpose in life, which is to make other plants just like them, is finished. If they're still getting water and sunlight, they may linger on for the warm months of fall, perhaps even put out a few unenthusiastic blooms, but it doesn't take much cold to convince them it's time to fold the tent. Their seeds will sleep, insulated by the earth, until warmth, water and sunlight in the spring cause them to sprout and rise again.

Other plants, usually referred to as perennials, which can include flowering plants, shrubs and trees, have deep root systems, again kept warmer by the earth. In its dormancy, and often without leaves, the plant is able to draw nutrients from the root material. The plant may drop leaves and blossoms, twigs die on the end and the whole plant can look like it's dead but, again, warmth and moisture will call them back to life after several months of dormancy.

More specifically, lots of grasses have still more protection, in that they already are growing low to the ground, where there is a thin layer of air warmed by the reflection of the sun on the earth. Decomposing organic material in the soil causes warmth to be generated year-round, which protects roots from freezing. There are parts of the world, of course, where even the soil freezes, and the plants that survive from year to year there have even more sturdy survival tactics. In parts of the world where it gets that cold, even grasses often have to be replanted every year. However, in the more temperate parts of the world, many grasses have rhizomes, underground root systems, really tubers, that can go as much as 18" deep in the dirt, ride out the cold, and pop up, usually where you don't want them, at the first sign of warm air.

 

More General Botany Questions

Genetics reason for color variation in Indian paintbrush
April 03, 2005 - Are the color variations in Indian paintbrush (Castilleja indivisa) a matter of genetic mutation or minerals in the soil? I say it's genetic and the rest of the family says it's environmental.
view the full question and answer

Why do sunflowers turn towards the sun?
February 27, 2006 - Why do sunflowers turn towards the sun?
view the full question and answer

Have invasive plants no useful purpose from Anchorage AK
September 03, 2011 - Does the definition of invasive plants include that the plant has no useful purpose? Thanks.
view the full question and answer

Why do some flowers open during the day and close at night?
April 08, 2009 - My son is doing a science fair project on the California Poppies. We are trying to find the definitive answer on why the flowers open during the day and close at night.
view the full question and answer

Information about Turk's Cap for school project
October 19, 2012 - Hello, my name is Veronica. I am doing a Species Study on Turk's Cap at Clint Small Middle School in the Green Tech Academy. I would like to learn more on my Native Texas Species. I am contacting you...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP | STAFF
© 2016 Lady Bird Johnson Wildflower Center