Together Until Harvest
In Bible History, tares generally refers to the bearded darnel, a species of noxious grass (lolium temulentum) that, until it matured, was very similar in appearance to the wheat that it commonly infested. The difficulty in controlling it was that, while small enough to be weeded, it could not easily be discerned from the wheat, hence much wheat would be unintentionally pulled up in the process, whereas by the time it became recognizable, it could not be pulled up without pulling up the wheat as well because of their by-then closely-growing root systems. The only economical response was to wait and then separate the wheat from the tares as both were harvested.
"Let both grow together until the harvest"
Jesus Christ used tares in a parable of why there is yet evil in the world - for the sake of the righteous, the wicked are not yet destroyed:
"Another parable put He forth unto them, saying, The kingdom of heaven is likened unto a man which sowed good seed in his field: But while men slept, his enemy came and sowed tares among the wheat, and went his way. But when the blade was sprung up, and brought forth fruit, then appeared the tares also."
"So the servants of the householder came and said unto him, Sir, didst not thou sow good seed in thy field? from whence then hath it tares?"
"He said unto them, An enemy hath done this."
"The servants said unto him, Wilt thou then that we go and gather them up?"
"But he said, Nay; lest while ye gather up the tares, ye root up also the wheat with them. Let both grow together until the harvest: and in the time of harvest I will say to the reapers, Gather ye together first the tares, and bind them in bundles to burn them: but gather the wheat into my barn." (Matthew 13:24-30 KJV)
The Messiah used parables to teach, but to teach in a limited manner, for that time.
"All these things spake Jesus unto the multitude in parables; and without a parable spake He not unto them: That it might be fulfilled which was spoken by the prophet, saying, I will open my mouth in parables; I will utter things which have been kept secret [see also Mystery] from the foundation of the world." (Matthew 13:34-35 KJV)
It was only later, after the crowds were gone, that The Lord explained the ultimate meaning of the parable to The Elect:
"Then Jesus sent the multitude away, and went into the house: and His disciples came unto Him, saying, Declare unto us the parable of the tares of the field."
"He answered and said unto them, He that soweth the good seed is the Son of man; The field is the world; the good seed are the children of the kingdom; but the tares are the children of the wicked one; The enemy that sowed them is the devil; the harvest is the end of the world; and the reapers are the angels. As therefore the tares are gathered and burned in the fire; so shall it be in the end of this world. The Son of man shall send forth his angels, and they shall gather out of his kingdom all things that offend, and them which do iniquity; And shall cast them into a furnace of fire: there shall be wailing and gnashing of teeth. Then shall the righteous shine forth as the sun in the kingdom of their Father. Who hath ears to hear, let him hear." (Matthew 13:36-43 KJV)
Fact Finder: What is meant by the Biblical term "baptism of fire"?
See Baptism Of Fire