You can buy the produce and just plant that, no need to actually buy the seed. Or you can go exploring for them. Plus there are books and the gardening channel. If your sim doesn't have a job plant a lot of stuff to raise it fast.
"I hear voices in my head, but they speak Spanish. So I have no idea what they're saying" Daniel Tosh
You can increase gardening by reading a book (buy it or go to the library), or by planting things and tending to them (takes quite a while).
Different items require different skill levels to plant.
To plant something, either place it on the ground then click on it and select "plant here," or select the "plant" option when the object is in your inventory, then click where you want to plant it. These options will only appear if you have a high enough skill level for that thing.
I don't know how long it will take to reach level 7, but if you have enough points you can buy the Super Green Thumb reward, which might make you learn faster.
I got gardening up to 10 by simply finding seeds around the Central Park type area and the different fishing holes and maintaining the garden I planted using them. I think I may have used books for levels 7 and 8 or something around there.
From: CJayC | Posted: 6/3/2003 GameFAQs isn't going to be merged in with GameSpot or any other site. We're not going to strip out the soul of the site.