It is implied that the Russians did. Umberto was carrying a cargo of triffid seeds.
Triffids begin to appear.
The Russians could have possibly engineered them, but most of their background is unidentified.
It is discovered that triffids can walk.
Bill gets stung by an immature triffid.
He doesn't die, and this builds up his resistance to triffid venom.
Bill enters Arctic and European Oil Company.
He wants to study triffids more closely.
Walter shares his theories about triffids with Bill.
Walter's theories are about how the triffids use the 3 sticks to communicate, and how he thinks they have some form of intelligence.
Bill is temporarily blinded by some triffid poison.
The day the green "comets" came.
It is later said in the book that the green comets could actually have been the result from a crash between comet debris and a satellite holding biological weapons.
Bill saves Josella, they find triffids have attacked.
They find her father dead, as well as Annie. They narrowly escape from the triffids.
Most people wake up blinded, Bill doesn't.
He wasn't able to see the "comets" due to bandages on his eyes from triffid poison.
Bill and Josella set out for the University.
After thinking, they decide that what's best would be to stick with Beadley.
The University meeting - Bill and Josella stay.
Bill is kidnapped by Coker's gang.
Torrence shoots at Bill's gang.
He shoots at them for trespassing into his territory.
Bill's gang is attacked by triffids.
Bill escapes, unharmed, and he thinks about leaving, then changes his mind when a young girl persuades him.
Bill's base is consumed with the "plague."
He finds the girl who persuaded him to stay dying, and gives her a pill to finish it quickly. He sets off back to the University.
Bill discovers that Beadley has moved to Tynsham.
He meets up with Coker, but what they don't know is that Josella is there too. She had been scared by the sound of Bill shooting a triffid.
Coker and Bill head out for Tynsham and arrive.
Bill and Coker meet Miss Durrant.
Miss Durrant reveals that she and Beadley have split, due to differing views. However, her group is in bad conditions. The only way for them to survive would be to follow Coker's ideas, but she stubbornly refuses to comply.
Bill and Coker meet Stephen's group.
Instead of Beadley, they meet Stephen. Stephen's group consists of him, his girlfriend, a sullen stranger, and a raving (almost) crazy man, who joins later.
Bill and Coker leave Tynsham and get to Beaminster.
They had been (falsely - as they later found out) informed from Miss Durrant that Beadley's party had set out for Beaminster.
Bill searches for Josella with the help of the group.
They search till May 25, even using a helicopter, but to no avail.
Bill goes to the Sussex Downs to find Josella.
Bill meets Susan and takes her with him.
Bill and Susan find Josella.
Mary gives birth to her daughter.
Bill goes to Tynsham and finds the plague got it.
3 weeks from Mary's daughter's birth.
Bill visits London twice.
Once for triffid weapons, food, books, Braille books, engine parts and paper. And the second time was for clothing (this happened a week after the first trip.)
Josella gives birth to David.
Bill turns his attention to the growing triffid population.
Susan has been watching them carefully, and so has everyone else. Bill has not noticed because he is so used to them.
Bill discovers triffids can hear.
Susan shows him how they alter their course when they hear a gunshot. They devise many traps to lure away the triffids because they are building up.
The triffids break the fence.
Susan finds them in the morning, leaves plastered against the window.
The triffids break in again.
4 months after initial attack. They also discover some triffids have been trampled in the process of breaking in.
Bill builds an electrical fence to deter the triffids.
This works fairly well, and keeps them free of break ins for a year or more.
Bill makes his last trip to London.
He discovers that it is unsafe because of the deteriorating buildings that could collapse at any moment.
Bill and Josella see a helicopter while on the coast.
Bill and Josella rush back to Shirning and meet Ivan.
Ivan was flying the helicopter - mentioned earlier in the book.
Bill's group learns about Beadley's party from Ivan.
Beadley has found that to survive, he is going to need an area that can be cleared of triffids. He chooses the Isle of Wight, so that once the triffids are cleared out, they won't be able to return easily. Bill decides to take his time getting there.
Bill meets Torrence (again).
Torrence once shot at Bill, when he was chained in Coker's gang.
Bill learns about Torrence's feudal seigneury plan.
Torrence wants 20 people to survive off of Shirning, and for Susan to be moved elsewhere. Bill pretends to be persuaded, but he is actually forming a plan.
Bill's group escape from Torrence to Isle of Wight.
The group's plans to move are rushed when Torrence finds them.