In a modern man kind of way, it is George who has been to the garden centre to buy plants. This gives the impression that the garden is now George's responsibility. It could be that they were both going to go but Jill turned up, causing George to have to go on his own, and perhaps buying the wrong sort of plants in a hilarious 'getting the wrong end of the stick' way. You can almost hear the catchphrase and canned laughter.
Jill has recently has breast implants. It is thus fair to say that Jill is rather well off. Breast implants were not that common during the early 80s and probably rather expensive. Jill wanted large fuller breasts but she may end up getting more than she bargained for. The 3rd generation of breast implants, with a thicker coating on the silicone gel, didn't come in until the mid 80s, and probably after Jill's surgery. There is therefore a rather high risk of the gel sac splitting and costing Jill another time under the knife.
This might actually be happening already. Jill's dress is clearly fastened when George arrives home but by the time she leaves it has burst open to reveal her bra. Now this may be because she has yet to update her wardrobe but we must fear the worst. The surgeons in Wimbledon are not yet adept at the cosmetic end of the profession, and this is evidence of that.