Okay, well there is tropism and stimulus. The stimulus can be gravity, light, and touch. So it depends... If there is a window above the plant and it is reaching upwards towards it... then it would be light, and the plant's response would be reaching upward towards it.
sunlight
The plant will still grow upward away from gravity
We had a pumpkin plant. It didn't really grow up, but it did grow outward. If you plan on planting pumpkins, make sure to have a lot of space.
water pressure inside the seed coat
Gravitation effect on a plant's growth is called geotropism. It affects it by it's height,and sometimes affects how many flowers it produces. It causes roots to grow downward (positive geotropism) and stems/branches to grow upward (negative geotropism). So it gives plants an 'up' and 'down' or lateral directions to grow the correct structures in the right places.
Auxin is a chemical which makes plants grow faster.Specifically, the chemical in question can be described as a plant hormone or phytohormone to regulate growth. The terms comes from the Greek word αυξειν (auxein) for "to grow, to increase." Auxin may occur naturally -- often in cooperation with the plant hormone cytokinin -- or synthetically.
plants grow upward, because they are attracted to sunlight. This causes them to follow the light and grow closer to it. For instance if you put a growing plant in a pitch black room, except for, say a flashlight, to its right side for a certain amount of time the plant will grow to its right side.
organisms
If a plant is tipped on its side, the shoot will still grow upward.
The plant will still grow upward away from gravity
We had a pumpkin plant. It didn't really grow up, but it did grow outward. If you plan on planting pumpkins, make sure to have a lot of space.
to make it easier to grow
Gibberellin
Your plant is reaching for more light, place plant in a brighter area.
The sugar in 7-up causes the plant problems
They grow upward because the growing stem has the ability to sense up and down, largely through bending of the stem in response to gravity and then grows faster on the inside of the bend and slower on the outside of the bend, causing the bend to straighten out and grow upward. Once in view of light they grow toward light, which is also usually up not down. These are evolutionary adaptations to help the plant get the energy it needs to survive after the "food" in the seed is consumed.
Plant layering is usually done by forcing a section of the plant's stem or branches back into the ground. This allows that stem to grow upward and create a new plant.
The Sun.