Horticultural Potting Grit A great versatile product, Horticultural Potting Grit is washed and lime-free grade potting grit. The perfect accompaniment for cacti, succulents, alpines as well as bulbs. Horticultural potting grit provides extra drainage when added to compost and when dug into heavy soils. Using Horticultural Potting Grit Improve drainage by using potting grit. To use, simply dig over the soil and incorporate the potting grit. The tiny pieces of grit will then create air holes so water can drain through the soil more efficiently. The newly created pockets of air also aid root growth. And/or dressing the top of pots to prevent water splash - as recommended by Monte Don.