For a set to be 'on' an imaginary line drawn through the centres of the touching balls needs to form a direct line to the pocket.

When playing a set you should always aim so that when the cue-ball makes contact it will form a straight line with the other two balls, as if you were aiming to pot the ball you're aiming at. If you make any other contact you may miss the pot, and this will be explained further on.

For a plant to be 'on' an imaginary line drawn through the centres of the touching balls, and another from the centre of the ball to be potted and the pocket, need to form a right-angle.

When playing a plant you have more margin of error, but these too can be missed if you're not careful.

Either shot can give you a wonderful opportunity to begin a break, but some are not so easily seen.

Sometimes a Plant or Set can be 'hidden' by an intervening ball that prevents a direct shot being played.

They most commonly occur shortly after the frame has begun, so when there's no obvious pot to go for, make sure you study the reds carefully. If you find one and decide it's too risky to take on you'll need to make sure you don't leave it for your opponent.

Another time to look carefully is after your opponent's made a foul stroke. You don't want to make him play again only to see him get straight down and pot one !

You will find it useful to practice these. Especially if you rarely play English Billiards and lack the experience of playing cannons as accurately as you'll need to to make these shots.

Sometimes you'll need to play 'cushion first' as if you were snookered, and these are the ones that most players fail to see. They are also the easiest to miss, so if you take them on then play with the greatest care.

Each example gives three different positions of where the Plant or Set might be. In each case, the balls nearest the cushion are the easiest, and are well worth an attempt.

When the balls are in the middle of the table, somewhere around "B", they are much more difficult but may still be a realistic proposition - especially if you know your angles.
But when the balls are at "C", they are far riskier and may only be worth attempting if you're a long way in front or you cannot play at any other reds.

None of the Plants or Sets shown in this diagram can be made if you play them normally. In each case the red would miss the pocket by several inches.

But both Plants can be made by playing with screw. To make the one on the left aim to hit the red slightly to the right of centre as you see the shot on your screen.

The general belief as to why this happens is that at the moment of contact the middle ball is trapped for a split second, and the cue-ball spinning backwards transfers a tiny amount to the object-ball - as if they were cog wheels, where itis reversed into top-spin.

This top-spin then pulls the object-ball forward as it is pushed out, and it then travels along a different line than you would expect.

The Sets can both be made by striking the first red on the side opposite the pocket. This seems illogical, but it works !   A little practice at varying distances from the pocket will teach you how easily these can be made.

Practice these shots in different areas of the table. They all have to be 'made' and can never be guaranteed, so learn how to play them before you attempt any in a competitive game.