I know that when growing in soil, the soil temps make a big difference in how well the plant grows. But, I am sure the part above ground would benefit from heat as well. You can buy an inexpensive electric heater that has a built in thermostat in it. It will not be as accurate as your house thermostat and heating system, but some variation in temps isn't a problem. You just need to keep the plants in a temp range.

Just buy one or two of those wireless thermometers and place the remote sensor among the plants and then you can place the display in your living area to monitor the temps. Set the heater(s) so it is keeping the plants in the 60-80 degree range.

Hydro nutrient temp should be below 75F so that it will hold dissolved oxygen. Use a small electric space heater to heat the ambient air.

Willardb3

if the ambient temps are higher than 75 how can I make sure my nutrient solution stays cool enough? Will it not heat to around the same temp as the air around it after time?

Put ice in the nutrient reservoir.

Adiabatic cooling (evaporation) will also reduce the nutrient temperatures.

Cooling required is pretty much system specific.