Research the best times to fertilize your plants—most will require fertilizer when first planted, and some will call for replenishing fertilizer as they grow. Beware of over-fertilizing, which can burn plants or force them into the flowering stage too early. This can result in bitter tasting and less abundant produce. Water plants well once or twice a day, preferably in the morning and evening, when they're out of the strongest sunlight. Midday watering can give leafy plants brown spots.