The appeal of a mason jar herb garden is immediate, transforming a sunny kitchen window into a vibrant, fragrant display. This method is popular for those with limited space, offering a functional way to keep fresh herbs on hand. Growing herbs in a glass jar presents a unique challenge because the container lacks a traditional drainage hole. Success depends on meticulous setup and maintenance, allowing you to cultivate a thriving indoor garden that provides fresh flavor near your cooking area.
Choosing Your Herbs and Supplies
Selecting the right container is the first step. Wide-mouth quart (32-ounce) mason jars generally provide the best balance of root space and stability. Using a larger jar allows the plant’s root system more room to develop, as plants often grow only to the size of their container. A wide opening also makes the planting process easier and provides better air circulation for the growing herb.
The choice of herb is paramount, as some varieties tolerate the non-draining environment better than others. Non-woody, tender herbs like basil, mint, chives, parsley, and oregano are excellent choices for this small-scale container setup. These herbs tend to have shallower root systems and are more forgiving of indoor conditions than deeply rooted or woody varieties like rosemary. Avoid herbs that require perfectly dry soil or grow into large shrubs.
You will need a lightweight, sterile potting mix formulated for container gardening, not garden soil, which compacts too easily. The other non-negotiable supply is material for a drainage layer, such as small pebbles, gravel, or horticultural charcoal. This layer is an internal reservoir designed to collect excess water, preventing the roots from sitting in saturated soil and succumbing to root rot. Activated charcoal is particularly beneficial as it can also absorb impurities and reduce the risk of mold or odor developing.
Planting Instructions
Begin the assembly by creating the internal drainage system at the base of the jar. Pour in your chosen material—pebbles, gravel, or charcoal—to create a layer approximately one to two inches deep. This layer separates the soil from the water that inevitably settles at the bottom of the non-draining vessel.
Next, place a thin barrier, such as a piece of mesh screen or a small coffee filter, directly on top of the drainage layer. This barrier prevents finer soil particles from filtering down and clogging the air pockets in the gravel, which maintains the drainage layer’s function. Without this separation, the soil would mix with the pebbles, eliminating the space meant for excess water.
Fill the jar with the potting mix, leaving approximately one inch of space between the soil line and the rim. This space is necessary for watering and allows for proper air circulation at the soil surface. If starting with seeds, sow them according to the packet instructions and cover them with a thin layer of soil, gently firming the surface.
When transplanting small seedlings, carefully remove the plant from its nursery pot and gently loosen the roots to encourage outward growth. Nestle the plant into the jar so the base of the stem is level with the surrounding soil. Once positioned, lightly pack the soil around the seedling to remove air pockets, and then provide a small initial watering to help settle the soil around the roots.
Long-Term Maintenance
Mastering the watering technique is the most important factor for long-term success in a jar without drainage holes. Since there is no escape for excess moisture, the goal is to add just enough water to wet the root ball without saturating the drainage layer. Check the soil moisture by inserting a finger or a moisture meter several inches deep, only watering when the soil feels dry at that depth.
Overwatering is the primary cause of failure, leading to root asphyxiation and rot. When watering, apply it slowly and sparingly, using only a small amount to moisten the soil around the plant. Avoid seeing a visible layer of water accumulate at the bottom, which signals over-saturation.
Most herbs require substantial light, ideally six to eight hours of direct sunlight each day to maintain dense, flavorful growth. A south-facing window is usually the best placement indoors. If natural light is insufficient, the plants will become “leggy,” stretching weakly toward the light source. In such cases, supplemental light from a small LED grow light positioned a few inches above the plants can provide the necessary energy for healthy photosynthesis.
Regular harvesting encourages the plants to become bushier and more productive rather than tall and spindly. To prune correctly, use clean shears to pinch or cut the stem just above a leaf node, the point where a new set of leaves or a branch emerges. This action stimulates the plant’s hormones to promote lateral growth, resulting in a fuller herb plant.
If you notice issues like mold on the soil surface or a foul odor, it often indicates poor air circulation and excessive moisture. To mitigate this, ensure the soil surface is allowed to dry out between waterings, and occasionally loosen the top layer of soil with a fork to improve aeration. By consistently monitoring moisture and providing adequate light, your mason jar garden can provide a steady supply of fresh herbs.