Does Pot Size Matter to a Plant's Growth?

Root Needs

• Plant roots collect and store nutrients and energy for the plant. As the plant grows, so do the roots. A too-small pot causes the plant roots to become bound as they wrap around the inside of the pot and begin to constrict themselves. A bound plant usually grows poorly and eventually begins to decline as the plant chokes itself. Symptoms of a bound plant in a too-small pot include roots growing from the drainage holes and the plant lifting itself from the soil as the huge root mass forces it upward.

Large Pot Problems

• Planting in a pot that's too large for the plant's root system results in a waste of potting soil and space, but it also impacts the health of the plant. Overly large pots require more water, and most of the water is lost to evaporation and drainage because the roots cannot use the volume absorbed by the soil. The large volume of unfilled soil may hold onto too much water and cause the roots to rot. Some plants grow to fit their pot, whatever the size, so planting in an overly large pot may result in a plant that is too big and difficult to maintain.

Drainage

• Drainage is one of the most important considerations when choosing a plant container. An overly small pot drains poorly once the roots begin blocking the drainage holes in the bottom. The soil also doesn't contain the necessary volume to hold onto enough moisture, necessitating more frequent irrigation. Pots that are too large for the plant drain better, but the water is lost since the roots can't use it all. Choosing a pot the right size for the plant -- then repotting it every one to two years as the plant outgrows the pot -- will ensure the best health and moisture use by your plant.

Stability

• Large, top-heavy plants can suffer damage if their pot falls or blows over. A fallen plant can suffer broken stems, leaf damage or loss of flowers and buds. A larger, heavier pot anchors the plant and keeps it upright, regardless of how large the stems and foliage grow. Choose pots with a depth able to support the length of the entire root system, as tall plants typically produce long taproots to anchor them. Avoid shallow pots and pots that are too narrow to support the height of the plant. Shallow pots are only suitable for low-growing plants with shallow root systems.