It is the 21st century, and all transportation on Earth is provided by T-Mat, a matter teleportation system operated from the moon. But as the Doctor, Jamie and Zoe arrive, the T-Mat station is taken over by the Ice Warriors. The Martians plan to turn the Earth into a new Mars by spreading special seeds over the planet which will alter the Earth's climate, and T-Mat is to be the method by which their horrible plan will be accomplished.

Shortly after the broadcast of The Ice Warriors at the end of 1967, Doctor Who producer Peter Bryant requested a new story involving the eponymous Martians from their creator, Brian Hayles. His motivation was twofold: the Ice Warriors had been a popular addition to the programme's monster menagerie, but their costumes had also been very expensive and a return appearance would better justify the cost. On February 2nd, Hayles was commissioned to write a storyline for a six-part adventure called “The Lords Of The Red Planet”.

However, it appears that this idea was not to the satisfaction of the production team, as a new storyline was commissioned from Hayles on July 15th. This was titled The Seeds Of Death, and was either an entirely new concept or else a heavily modified version of “The Lords Of The Red Planet”. The Seeds Of Death evidently proved more acceptable, and the scripts were subsequently commissioned on August 28th. Hayles was asked to write the Doctor out of episode four to permit Troughton to take a week's vacation.

Hayles' scripts differed from his story breakdown in several respects. Kelly was originally a man, assisted by a woman named Mary Burcott; with the former changed to the female Gia Kelly, Mary became Brent. The Ice Lords were envisaged as more humanoid than their Warrior counterparts, and episode two would have introduced Slaar's superior, named Visek. The Martian spores were only intended to erupt after four weeks rather than almost instantaneously, and were initially destroyed by concentrated oxygen (possibly in a liquid form) instead of water.

Hayles had also been informed that Frazer Hines would be leaving Doctor Who in the story preceding The Seeds Of Death and so was told to replace him with a new companion named Nik. While Hayles composed his scripts, however, Hines' status became less certain: the identity of the male companion changed from Nik to Jamie back to Nik, leading the author to write the role for an unspecified character. Just as Hayles submitted the last of his scripts, it was confirmed that Hines would, in fact, be remaining on Doctor Who until the end of the season, at the request of Patrick Troughton. Hines agreed to a contract for The Seeds Of Death on October 9th.

Unfortunately, the production team -- which now consisted of Bryant, former script editor Derrick Sherwin, who was trailing the producer in anticipation of taking over the top job, and new script editor Terrance Dicks -- was not happy with Hayles' work. The writer explained that his difficulties had stemmed from the uncertainty over Jamie and difficulties adapting his storyline to allow for the Doctor's absence in part four; the BBC countered that Dicks had provided him with ample warning on both counts. Hayles took a stab at rewriting The Seeds Of Death, but by the end of October, it had been decided that Dicks would redraft the final four episodes. Formal approval for this measure came retroactively on December 13th.

Significant deviations from Hayles' storyline were introduced into parts three to six. Most notably, a subplot in episodes three and four in which Kelly was mind-controlled by the Ice Warriors was removed, while the Martian fleet lead by the Grand Marshall was introduced into the concluding episodes. A late change saw the removal of a line in which Eldred reveals that his rocket achieved the first manned moon landing; this was altered to account for the likelihood that NASA would probably soon accomplish the feat (as in fact they did on July 20th, 1969).

The director assigned to The Seeds Of Death -- given the production code Serial XX -- was Michael Ferguson, who had last helmed The War Machines three years before. His work began with model filming at the Ealing Television Film Studios on December 13th. After the weekend, three days of live action filming took place at Ealing starting on the 16th; this covered sequences set outside the Weather Control Bureau. A single location day followed on the 19th. Taking place at Hampstead Heath in London, the principal concern was the material involving the Ice Warrior abroad in the city. Two more model days at Ealing, on the 20th and the 23rd, completed filming.

Studio recording would normally have begun on December 27th, but this was delayed until January 3rd, 1969, due to the Christmas holidays. As usual, all six episodes of The Seeds Of Death were recorded on consecutive Fridays in Lime Grove Studio D. On January 7th, the press revealed that Troughton would be leaving Doctor Who in the summer. Troughton was absent from the recording of part four on January 24th; his return the following week coincided with a rare instance of an episode being captured on 35mm film rather than videotape. Even more irregularly, Ferguson made use of out-of-sequence recording for all six installments, most notably on episodes two and three. Production wrapped up with the taping of part six on February 7th.

• Doctor Who: The Handbook: The Second Doctor by David J Howe, Mark Stammers and Stephen James Walker (1997), Virgin Publishing, ISBN 0 426 20516 2.
• Doctor Who: The Sixties by David J Howe, Mark Stammers and Stephen James Walker (1992), Virgin Publishing, ISBN 1 85227 420 4.
• Doctor Who Magazine #274, 10th February 1999, “Archive: The Seeds Of Death” by Andrew Pixley, Panini UK Ltd.
• Doctor Who Magazine Special Edition #4, 4th June 2003, “Paradise Lost” by Andrew Pixley, Panini Publishing Ltd.