The Ponderosa lemon tree resulted from a cross between a citron blossom and a dwarf lemon tree blossom in the backyard of a Maryland home. The resulting small tree with mammoth fruit grows easily in containers. Lemons in general hate the cold weather, so the care of this hybrid usually involves bringing it indoors during the winter. The fruit produces a sweet juice with a thick peel that cooks like to use in baking and candy-making. The Ponderosa lemon tree blossoms profusely and then sets as much fruit as the tree can support for its size, making this tree perfect for patio or backyard gardening.
Citrus trees grow in many soil types as long as they have good drainage. Soils that tend to hold the water often cause the roots to rot, stunting the tree's growth. Sandy soil drains the best, but just sand in a plant pot provides very few nutrients. A mix of garden soil, sand and compost in equal parts will provides a good source of nutrients for the tree and good drainage.
Water provides the conduit for nutrients, but Ponderosa lemon trees shrivel, shrink and die when their roots sit in water--drowning from a lack of air. The key difference between one tree's health and and another's disease, lies in how well the soil drains around the roots. Plants that grow in pots that drain the water away from the base of the plant can tolerate larger amounts of water.
Ponderosa lemon trees need an acid soil with a pH of 5.5 to 6.5. A top-dressing of elemental (agricultural) sulfur for alkaline soil--or for a quicker pH reaction, actually worked into the soil--remedies the pH level. Use a balanced fertilizer during the growing season, preferably diluted with water, every couple of weeks.
Lemons and citrons are tropical plants, which means they need direct sunlight and heat. During the active growing season, provide direct sunlight for eight to 12 hours a day and indoor shelter during cold winters. Six hours of sunlight a day during the winter months will help keep it healthy if your home doesn't get enough sunlight.
Ponderosa lemon trees typically do not need pruning expect to remove damaged wood resulting from cold damage or disease. Trim back the portion affected to healthy wood, cutting at a 45-degree angle.