What makes a plant stop growing at a certain height?

I potted two Amaryllis bulb. Early on, they were quite different heights. But by three weeks they were within a millimeter or two of ech other. What made them stop growing at a certain height?

What makes a plant stop growing at a certain height?
Genetics...!
Reply:This is not the answer I was looking for. I want to know what hormonal or other chemical changes in the organism effect the stop in graowth. Report It
Reply:Plants are like people. Their height is controlled by their dna.



Probably one bulb was planted in a better soil, or had better light--and so grew faster. But eventually the other one caught up.
Reply:The final height of a plant is built into its genes. Your second plant caught up because of biological compensation. This is as the plants get older the difference between them become less different. This happens as the plants grow they can access more water and nutrients so the difference at the beginning becomes less important. The final height can be determined by flowering in some species but it is mostly control by genes. We sometimes try to breed shorter plants (with double dwarf genes) so less plant energy is put into vegetative growth and more energy can be used for reproductive growth. An example is wheat which is now very short now and more energy can be put into grain production.

Thanks Tim http://www.nuganics.com.au
Reply:Genes and roots limit height of plants.