At what temperatures to Citrus seeds germinate at?

Growing Citrus from seeds is easy, or, at least it should be. However when good natured gardeners try and flex their horticultural wings by planting these babies up for cossetting on their kitchen windowsill often nothing happens and their hopes are dashed! So what is going wrong? Assuming that all other conditions are correct then it is likely to be the soil temperature. So unless your windowsill is in the Mediterranean or some similar warm and lovely environment your seeds just won't have the impetuous to initiate germination. Therefore the question is this, at what temperatures to Citrus seeds germinate at?

The simple answer is at a surprisingly high temperature so assuming you live in a cooler temperate country you will certainly need a heated propagator - unless of course you sow your seeds during the summer months. 

Lemon seeds

A study by R. E. Rouse and J. B. Sherrod at the University of Florida tested the optimum germination temperatures of 17 citrus varieties using a temperature gradient from 15 to 38 degrees Celsius. The results showed that the optimum temperatures for germination Citrus seeds ranged from 25° Celsius for Citrus trifoliata to 33° Celsius for the Citrus limonia and Citrus sinensis hybrid rootstock. This gave a mean optimum temperature for all the citrus varieties covered in this study of 30°Celsius.

This is of course great for a laboratory experiment but for kitchen purposed I would suggest setting your temperature to approximately 25°Celsius with the view to increasing temperatures incrementally if germonation hasn't commenced after two to three weeks. With regards to the higher germinating temperatures it is worth considering manufacturing an insulated propagator using a polystyrene box (usually obtained from your local tropical fish shop) and a heat mat.

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