Do aquarium plants have seasons?

[Nells250]

Coming from outdoor gardening, I am curious if aquarium plants tend to have "seasons". This may be an absolutely SILLY question, but I can't help but wonder, especially when I see a plant have new growth when nothing in the tank has changed!

 

[Colin_T]

In the wild yes, but not always in the aquarium.

Aponogetons and water lilies normally have seasonal changes in the aquarium but most other plants don't. If the plants are grown in the wild or outdoors where the temperatures fluctuate and the water level rises and falls throughout the year, then most aquarium plants will flower and or die back/ go dormant for a bit.

Common marsh plants like Hygrophila sp, Echinodorus sp, Cryptocoryne sp will flower if you allow the water level to drop and the leaves to grow out of the water. This happens during the dry season in the wild and the plants flower then. Echinodorus also flower when kept underwater, however they don't produce a flower, instead they produce a baby plant where the flower should be.

Aponogetons and water lilies normally have a growing phase whereby they produce leaves and build up a rhizome/ tuber. After a few months of growth they flower, and after flowering they normally die back and rest for a few months. It's a good idea to remove them from the aquarium when they have died back and put them in the vege crispy section of a fridge for a few months.

Some true aquatic plants like Hydrilla and Elodea don't flower. Other plants like Cabomba and Ambulia can flower if they grow out of water. Vallis does flower if given variations in temperature throughout the year. Vallis remains underwater its entire life but produces small flowers that grow up to the surface where insects can pollinate them.

You can grow a lot of aquarium plants in pots with potting mix and just water them regularly. The marsh plants do quite well like this and some produce pretty flowers.

 

[GaryE]

I used to collect plants. If I got them into a tank early in the growing season (in Canada) they became year round plants. If I got them after July, they would die in the Fall no matter what.
This was across quite a few species. So many have seasons, if they come from a place where nature has seasons. Around the equator, I suspect they are adapted to more stability and continuity.
Now fish - oh yeah, there, we're talking seasonal changes with many.

 

[Nells250]

Hmmmmm... if I read all of that correctly, plants that can exist partially out of water may act seasonal, in a way, and flower, because it isn't submerged? Purely "underwater" ones do NOT. Did I get that right?

GaryE - fish have seasonal changes even if they don't get frozen into lakes and ponds? ;-)

 

[GaryE]

Fully submerged Canadian waterplants have a die off that by August, you can't reverse in aquariums, even with full lighting periods. They can look fantastic in August, but they will die in October. You can cheat if you remove them into a tank early in the season though, so it must be photoperiod triggered. Someone who isn't me must have studied that!

Fish can have major physiological changes depending on whether they come from rainy/dry season regions. They can also have breeding seasons, again, linked to rains. East African Nothobranchius are really neat to look into, as an extreme.

 

[Colin_T]

Hmmmmm... if I read all of that correctly, plants that can exist partially out of water may act seasonal, in a way, and flower, because it isn't submerged? Purely "underwater" ones do NOT. Did I get that right?

GaryE - fish have seasonal changes even if they don't get frozen into lakes and ponds? ;-)

Nearly correct. The plants need changes in light and temperature (seasonal fluctuations) to flower. If you have marsh plants like Echinodorus and Hygrophila species growing in a plastic pot with potting mix, and the weather is warm and they get 16 hours of light per day, when they are mature they will probably flower continuously until there is less light or the temperature drops. If these same plants are kept in cool conditions or only get 6 hours of light per day, they won't flower until it warms up and the days are longer.

Vallis is an interesting plant because it is a true aquatic plant that produces a flower. However, it needs cold water for a few months (generally with shorter lighting periods) before the water warms up. When the water warms up and there are long days (lots of light) the plant will flower even though the plants live completely underwater. It sends up a flower on a stem and the flower sits on the surface of the water where it can be pollinated.

 

[StevenF]

aquatic plants do have seasons but it may not be related to temperature. in streams and lake the temperature varies less than it does in air. However the mineral content and associated water parameters such as GH, KH, PH, can change periodically due to rainfall and snow melt. So in some places will see softer water in the summer while in others the water will softer in the winter. How the plant responds to these changes is often not will documented.

Even on land plant seasons may not be obvious. For example most plants flower in spring. However some don't. Some prefer to flower when the nights are long. Desert plants tend to flower after a significantly wet period. And in one tree only when it is windy.