Although it takes time, you can improve the drainage properties of clay soils with the addition of lots, I mean lots, of organic matter.

Each spring, spread a layer of compost in the beds, eight to 10 centimetres thick, and work it into the soil to a depth of 30 centimetres or more.

Pine needles are acidic and they can, on a temporary and localised basis, slightly reduce soil alkalinity.

Gypsum and soil sulphur are two other amendments that can reduce alkalinity; gypsum has also been found to help loosen clays soils in some cases.

follow instructions

Follow package instructions for application rates. Once plants are established, mulch with additional compost. It will help improve drainage in your clay soil, keep soil from compacting in heavy rains, and provide nutrients to your plants.