I have a nice garden in the back. Petunias, begonias, carnations. But during these dog-days of summer, it ain't looking so hot. What's the cause?
1. Is it a failure to properly water? or
2. Is it a failure to use copious amounts of "weed killer"?
If you think the problem is 2, but in truth, the problem is 1 --- well, too much "weed killer" will eventually kill all the nice flowers.
If you think the problem is 1, but in truth, the problem is 2 --- well, you might grow some healthy flowers, but they might be wrecked with weeds.
If you think the problem is a combination of 1 & 2 --- well, you gotta use your best "green-thumb" judgment as to the proper amounts of each: mebbe some more water, mebbe a little weed-killer every now and then.
However, If the problem definitely ain't 2 --- then no amount of "weed-killer" is gonna make the garden better.