Tips & Tricks
A good place to start with farming is the Catherby vegetable, flower and herb plots. It is the closest place to the bank, so if you need more seeds or farming items you can quickly make a bank run for them. Also in the time that you are waiting for your seeds to grow, you can go fishing and check on them every 5-10 minutes. That way you can practice fishing, cooking and farming at the same time.
If you are in need of lots of Compost just to have in your bank, go to the plots where the compost bins are (Catherby, Ardougne, Old Farm - because these are more close together) and make 3 bins full. In the long run you will have 3 times as much compost that you'd regularly get from one bin.
It's easy to carry a few main things at all times in your inventory so you can just hang out at the plots. For example: take the vegetable seeds you are planting (Potatoes) and bring the flower that will help fight against the diseases (Marigolds) and some herb seeds (Guam). Always bring the seeds you are planting and a rake, seed dibber, 2 plant cures, 2 watering cans, and 4 compost buckets. Then you are ready for anything that will come along. If you want, you can bring sacks to fill your produce with.
Need more buckets? Not a problem. It seems that people who buy the Compost tend to drop their buckets! Great way for collecting a bunch for when you make your own. There are also bucket spawns in Catherby if you tend to farm there regularly.
If you need produce to pay Gardeners to watch over your crops, pick up the produce other players have dropped from their crops and hand it over to the gardener.
Magic secateurs can be obtained as a reward for completing the A Fairy Tale Part 1: Growing Pains quest. They increase the amount of herbs, vegetables or hops you collect when farming by 10% when you wield them. 10% may seem small, but in the long run, it is very useful, and makes that quest worthwhile to complete only to get that farming tool.