Do plants/flowers grow faster during the day or night?

[Mr Buttons]

Just started on my first garden on the porch this summer. 75% of the plants have survived through my first summer of testing my green thumb, I can live with that percentage. :)

I'm just wondering if your average houseplant/flower grows quicker during the day, when it's receiving all the sunlight, or does it store that energy and use it to grow during the night?

I've noticed about 2 of my 8 plants shot up like 1"+ overnight, but I work second shift so I'd see them at like 11 pm, then again the next day at 2 pm. Makes me think they shot up overnight, but it could've happened during the morning hours as well.

If it matters, I usually water at night (to mitigate evaporation), and use miracle grow w/ the water as well.

[Blake]

There are too many variables to give a sensible answer. Different species, water and temperature regimes, soil types etc.

Plants grow by filling the newly divided cells with water. If the plant has insufficient water it will either not grow or grow slowly. As a result many plants do indeed grow faster at night because the amount of water available in the new growth is higher

However plants also need sugars and other nutrients to grow. So some plants grow most rapidly in the mid-late afternoon, when the water flow carrying nutrients to the leaves is highest, and when sugar production from photosynthesis is at its peak.

There are huge numbers of other variables as well, not least of which is simply when the plant is genetically programmed to grow. So it’s impossible to generalize on when your plants grow fastest.

[johnpost]

i think it is correct that plants grow more at night. the stored energy from the day is utilized in making the plant bigger and all the other things plants do.

[Blake]

i think it is correct that plants grow more at night. the stored energy from the day is utilized in making the plant bigger and all the other things plants do.

And what is your evidence for this generalisation?

[Mr Buttons]

I wish I could give more info about the plant types, but they're all just random stuff I've picked up at Lowe's. The most specific answer I can provide is they're normal flowery plants that you would pick up at Lowe's in the Mid-Atlantic region.

[janeslogin]

If you can figure out what plants you have, try the botany forum over at gardenweb.com. Most of gardenweb sucks but there are some knowledgeable people who visit the botany forum.

i think it is correct that plants grow more at night. - might look more reliable if supported by a link.

[johnpost]

i think it is correct that plants grow more at night. the stored energy from the day is utilized in making the plant bigger and all the other things plants do.

And what is your evidence for this generalisation?

botany reading, i don't have a cite.

plants take in carbon dioxide in the daytime and store energy.

plants take in oxygen at night because they are growing.

[Chez Guevara]

Steve Kay, Dean of the Division of Biological Sciences at UC San Diego argues like so:

While most people might assume that plants grow at a slow and steady rate throughout the day and night, Darwin and others found that they grow in regular nightly spurts, with plant stems elongating fastest in the hours just before dawn.

Link (http://www.eurekalert.org/pub_releases/2008-09/uoc--big090908.php).

[Blake]

botany reading, i don't have a cite.

Nuff said. Suffice it to say that it varies depending on all the variables I noted above, and many more, and that there is no simple answer.

plants take in carbon dioxide in the daytime and store energy.

Under some circumstances and for some species, yes. Under other circumstances and for other species, no.

plants take in oxygen at night because they are growing.

Total nonsense.

Plants (actually only most plants) "take in" oxygen at night because there is insufficient light to allow photosynthetic production to exceed respiratory demand. It has absolutely nothing to do with growth, and in fact the relative dark period oxygen consumption is slightly higher amongst plants that are losing biomass, for fairly obvious reasons.

[Skeptica]

Here is a video that shows bamboo growing a meter (3 feet) a day: http://www.youtube.com/watch?v=FfDOMwFX5Hg&feature=related

The video shows the growth in 24 hours, no telling which part was during the day and which part was at night.

I did witness many lotus growing 1 foot over night, but never 1 foot during the day.

And what is your evidence for this generalisation?

[rowrrbazzle]

A plant adds more height at night. The tendency of a plant to turn towards the sun works by inhibiting growth where light hits the plant.

[svd678]

If plants (I'm thinking common flowers) grow faster in the night, what is the purpose of "grow lights" to extend the hours of light?