Pine trees are evergreens that add a stately look to the landscape while providing color all year round. Belonging to the Northern Hemisphere, these conifers thrive in subtropical regions in the south as well. Pines are known to prevent or inhibit growth of plants directly under them, including those found in vegetable gardens.
Pine needles are highly acidic and known to alter the chemistry of the soil directly below. When these trees drop their needles, the soil absorbs the acid from them, thus preventing other plants from growing. Although some vegetables prefer slightly acidic soils, there are many vegetables and plants that fail to grow and develop in highly acidic soil. Gardeners can grow vegetable crops in raised beds full of compost and good quality potting soil or reduce acidity with agricultural limestone, available in most garden centers and nurseries.
Pine trees provide plenty of shade to the soil directly underneath. Depending on the variety grown, pine trees can reach heights to 100 feet and spread more than 50 feet wide. Vegetables that love plenty of sunlight will fail to grow in the soil underneath, with others enjoying the shade from the canopy of these conifers. Make sure vegetables planted under pine trees tolerate low levels of light and shade.
Competition for Moisture
Although some varieties of pine trees are drought tolerant, wide roots can prevent gardeners from installing drip lines underground. Irrigate vegetables by hand if planted under or near a pine tree to prevent them from drying out. Provide water during periods of rain as well, because pine trees block rain, causing the soil underneath to become hard and dry. Vegetables planted directly under pine trees have to fight for limited moisture and nutrients in the soil.
Poor Seed Germination
Although the resin in pine needles preserves plants, it also inhibits or delays vegetable seeds from germinating. Start vegetables grown directly under pine trees from seedlings rather than seeds. With proper care and maintenance, chances of seedlings growing and developing into mature plants are higher than those of seeds that may or may not germinate.
Consider planting vegetables that prefer slightly to highly acidic soils, have a moderate tolerance to drought and prefer full to partial shade under the pine trees. Water and mulch vegetables frequently, and fertilizer whenever needed to yield healthy vegetables.