Can someone help interpret this poem? Ive tried and i am lost?

Question

The name is To His Son

Any ideas???? Much appreciated

THREE things there be that prosper up

apace,

And flourish while they grow asunder far;

But on a day, they meet all in a place,

And when they meet, they one another mar.

And they be these: the Wood, the Weed, the Wag:

The Wood is that that makes the gallows tree;

The Weed is that that strings the hangman's bag;

The Wag, my pretty knave, betokens thee.

Now mark, dear boy—while these assemble not,

Green springs the tree, hemp grows, the wag is wild;

But when they meet, it makes the timber rot,

It frets the halter, and it chokes the child.

Answer 1

the last part makes it seem like "weed" marijuana destroys although things seem alright

Answer 2

okay, been teaching English 22 years.  Love poetry - here's my opinion:

Literally, the speaker is talking about a tree, the hemp used to make a hangman's noose, and a young man (the "wag").  So all those things are good in their own way, but when they come together for something other than what they were intended (in other words, the tree becomes a gallows; the hemp becomes a hangman's noose; the young man becomes the guilty party or victim), it's not a pretty sight.

The last stanza "Now mark, dear boy - while these assemble not/Green springs the tree, hemp grows, the wag is wild" - all are good when in their natural state.

"But when they meet, it makes the timber rot,/It frets the halter (the noose), and it chokes the child (the hanging)"

Figuratively speaking, I would say that the speaker is the parent of the child, lamenting the fact that what was MEANT to be beautiful and productive and admired (the tree, the hemp plant, and the young man) has become something other than what was intended.  Something with potential good has become unspeakable.