The environment that you are raising your plants in a raised garden situation or a raised bed situation is one of the main reasons that people do this type of gardening. You can control the PA to the soil the actual chemical make up to the soil. If you need to raise say strawberries like a little more acid soil, you can solidify the soil and raise even flowers that take a lot of acid. You can raise them in an area that alkaline soil like we have here. Also you can control the water that the plants gets. You can have a really wet soil if you have a plant that likes wet feet or you can control it by watering the plants that needs deep water and drying out in between. Also you can control humidity, you can put sprinklers and things like that, that will water the foliage of certain plants. While on the other hand some plants like tomatoes will have less disease only if you water the roots and not put a lot of water on the leafs. So disease and water and even soil fertility if you have a plant that takes a lot of top growth to produce that top growth you can put it on there in a raised bed. You don't have to worry about leaching and make most of the fertilizer and water that is available so they're mostly economical way to garden.