Instructions
Decide which berry to grow and look up its growth time. Go through the list and look for alternatives. For example, you would choose to grow Oran berries over Wiki berries. Both berries restore HP, but Oran berries grow faster. You can find berry guides on game websites, such as GameSpot and IGN, that list the characteristics of each berry.
Go to Route 208 and buy Growth Mulch, which is a plant fertilizer, from the Berry Master's wife. Stand in front of the patch of berries and press "A." Select the Growth Mulch from your inventory and spread it on the soil. The Growth Mulch will decrease growth time by 25 percent.
Plant the berries in a patch on a route or in a city that you visit often. Multiply the growth time of the berry by 0.75 to get the new growth time, since you added mulch. Get a timer and set it for the amount of time the berry takes to advance to the next stage. For example, a Kelpsy berry advances one stage every six hours with mulch. Look at a game guide on IGN or GameSpot to find the stage growth times of each berry.
Visit the patch of berries when the timer rings. Water the berries to make them grow faster. Watering your berries also increases their yield.
Use Action Replay cheat codes to make berries grow faster. Buy Action Replay and insert it in your handheld game console. Plug the game cartridge in and turn on both the Action Replay and the game. Enter the code that makes berries grow immediately. On GameSpot, there is a long list of codes you can sift through to find the code that speeds up the growth time of berries.