Whether you're a novice or experienced gardener, you're likely familiar with companion planting, the practice of planting certain plant species nearby one another to encourage growth, repel pests, and increase soil nutrients. Certain plants are mutually beneficial to each other, such as basil and tomatoes, or marigolds and cucumbers.

However, you also need to consider which plant combinations to avoid when preparing your garden each year. Every herb, grass, flower, and tree has specific needs—sunlight, water, and soil preferences—that enable it to grow and thrive. Some plant combinations may look beautiful next to each other but might hinder the growth of one or both plants due to their differing needs or because one plant's root system is more aggressive than the other's. Some cultivars may also produce a chemical reaction as a form of protection, which can harm other plants growing near them.

We consulted with experts to determine which plants shouldn't be grown together so that you can plan your garden with ease.

Basil and sage are favorites in any herb garden. Both herbs love the sun, so you may be surprised to learn that these are plants to never grow together because they have vastly different soil and watering preferences. "Planting basil and sage together may not be ideal due to their differing water requirements and growth habits," says Autumn Hilliard-Knapp, horticulturist at My Perfect Plants Nursery. "Basil prefers moist soil, while sage thrives in drier conditions."