Heater recommendations for greenhouse during winter months?

Greetings!! I am new to greenhouses and trying to get some information to help dad.

We put together a 10'W x 20'L greenhouse so dad can keep his plants alive during the winter months. This upcoming winter will be our second winter season and are looking for a more efficient & effective way to heat the greenhouse.

Last winter, we used a small Mr. Buddy heater. It performed ok, but we had to change out the propane tanks several times a week. It didn't seem to move the heat throughout the greenhouse.

What recommendations do would you suggest to heat this size greenhouse? Would it be better to stick with Propane or switch to Electric?

We live in Ohio and dad would like to keep the temperature above freezing.

Thanks!

BCG

Space heater with fan maybe.

it seems like you have tons of room in there and I don't see any thermal mass to hold in the heat that is produced during the sunlit hours. I would put about 5 or 6 55 gallon trash barrels filled with water to capture the daytime heat and give it off during the nighttime hours. That with the space heater you already have might work. It will definitely help. I would also line the inside with bubble wrap for added insulation. Save it when you get packages and tape it up all over. Or you could go to a big box store and just buy rolls of it. Between your heater, the thermal mass heat from water and the added insulation, and you should be good to stay above freezing. It will also decrease your propane usage, and yes, a fan to evenly , distribute the heat like the last person said.

it seems like you have tons of room in there and I don't see any thermal mass to hold in the heat that is produced during the sunlit hours. I would put about 5 or 6 55 gallon trash barrels filled with water to capture the daytime heat and give it off during the nighttime hours. That with the space heater you already have might work. It will definitely help. I would also line the inside with bubble wrap for added insulation. Save it when you get packages and tape it up all over. Or you could go to a big box store and just buy rolls of it. Between your heater, the thermal mass heat from water and the added insulation, and you should be good to stay above freezing. It will also decrease your propane usage, and yes, a fan to evenly , distribute the heat like the last person said.

it seems like you have tons of room in there and I don't see any thermal mass to hold in the heat that is produced during the sunlit hours. I would put about 5 or 6 55 gallon trash barrels filled with water to capture the daytime heat and give it off during the nighttime hours. That with the space heater you already have might work. It will definitely help. I would also line the inside with bubble wrap for added insulation. Save it when you get packages and tape it up all over. Or you could go to a big box store and just buy rolls of it. Between your heater, the thermal mass heat from water and the added insulation, and you should be good to stay above freezing. It will also decrease your propane usage, and yes, a fan to evenly , distribute the heat like the last person said.