Do you need a box spring for a platform bed. Due to its supportive design any mattress can be placed directly on a platform bedframe without the need for a box spring or foundation. In fact you couldnt even use a box spring with your adjustable foundation if you tried because the bed wouldnt be able to change form with the stiff box spring sitting on top of it. You do not need a box spring or a special mattress for a platform bed. This could be an adjustable base platform bed box spring or even a hardwood floor.
That said this does not address the issue of whether a box spring is needed to provide adequate support for your mattress or whether a particular mattress will work well on a platform bed. If you have a traditional bed frame you would need a box spring or foundation to place your mattress on. A platform bed will be lower to the ground than a typical non platform bed will be so it is important to take into consideration what your optimal bed height is. If the frame has slats however it is recommended that they be no more than 6 inches apart if youre using a memory foam mattress.
A platform bed differs from a traditional bed in that a mattress can be placed directly upon your platform bed without any need for a box spring or a foundation whereas in the case of a typical non platform bed youd need either a box spring or a foundation on top of your bed frame before you could place your mattress on it. You dont have to use a boxspring although the use of one depending on your mattress. All you need is a hard flat surface to set the mattress on. The platform bed is the most versatile since you can place any type of mattress directly on it without a box spring or foundation.
So in answer to your question a box spring is generally not needed at least from an aesthetic standpoint when using a platform bed. Do you need a box spring with a platform bed. If you choose not to use a box spring what are you going to put your bed on. It is best to pair a latex mattress with a foundation or a platform bed but some manufacturers may allow you to place a natural latex mattress directly on a box spring provided it is in good shape.
The mattress should perform well and be comfortable in all of these situations but the box spring standard still exists in the eyes of most companies. For traditional bed frames which usually have fewer number of slats than platform beds and therefore poor weight distribution you will need a box spring or foundation below the mattress for weight absorption. But consider the alternative. In conclusion you need to put a mattress on something and if its not going to be on the floor platform bed or power base you need a new boxspring.