This is a seed.

It doesn't look like much right now, but if you put it in the ground, give it some water, fight off invaders, and wait a little while.

After a few weeks within a little luck, you might end up with a head of lettuce.

1. It doesn't look like much right now.

much 是个代词，作 like 的宾语。意思是“重要；意义重大”，用于否定句。又如：

This doesn't look like much, but can you see what this means? 

这看起来没什么，但是您知道这意味着什么吗？

It may not look like much but it has been part of our Christmas celebrations for so many years. 

他可能看起来并不起眼，但却陪伴我们从小到大，度过了很多个圣诞佳节。

2. in a few weeks 和 after a few weeks，都可以用于将来时。区别是：

前者指某个动作“在几周后才开始发生”；后者指某个动作“持续了几周以后，另一个动作发生”。比较：

My friend will arrive here in a few weeks. He will stay here with me. After a few weeks, he will leave for Shanghai.

（1）in a few weeks 几周后到达 （2）after a few weeks 过了几周后（指：呆在这里持续几周），再动身去上海。

网友的句子是指：“种子埋在土里几周之后，另一个动作（长出叶子）发生”。