1. Smurfette was created by Gargamel. She is not an actual Smurf and therefore can not mother any of the Smurfs. Sassette is another female, she was created using the same spell Gargamel used. There is a Granny Smurf but it was never explained how she was created, but she was not born in the same as the other Smurfs.

2. All the Smurfs are 100 years old and there were 99 original Smurfs. So obviously their process of reproducing is not one that can be done rapidly..

3. There are multiple types of asexual reproduction. For instance, fungi reproduce asexually and the the offspring is not an exact copy of the parent.

4. You all seem to forget the most obvious answer: magic. The only baby in the entire show was BROUGHT BY A STORK. Therefore, the baby Smurfs must come from a magical source. (Wikipedia has it listed as Smurfette giving birth to him for some reason, but all you have to do is look up the episode.) The only other children in the show are the Smurflings who came about due to a de-aging spell setting them back fifty years.

So where do Smurfs come from? A Stork literally brings them.

Smurfette was created by Gargamel to infiltrait smurf villiage. Smurfette had black hair until papa Smurf turned her ‘good’ and also into a blond. You can see this in the episode “The Smurfette” I beleive the other Smurf females were variations of this same concept to add more females later in the production run