Peat pots are biodegradable containers, typically made from compressed peat moss and wood fibers, designed to simplify transplanting by eliminating root disturbance. Unlike plastic containers, the fibrous walls of a peat pot are absorbent, acting much like a wick. This unique composition requires careful moisture management. The pot material must remain damp enough to prevent the soil from drying out but not so saturated that it promotes mold or prematurely disintegrates.
Determining When to Water
The most reliable way to assess a peat pot’s moisture level is not by visual inspection alone, as the surface of peat moss can appear dry even when the soil beneath is still moist. A quick and practical sensory check involves the “lift test,” where you pick up the pot to gauge its weight. A pot that feels surprisingly light indicates that the water content has significantly depleted and it is time to rehydrate the material.
Visual cues can supplement the weight test, particularly the color of the pot material itself. When fully saturated, peat pots are a dark, rich brown, but as they dry out, the color fades to a much lighter tan or khaki shade. If the pot feels light and the majority of the material has lightened in color, the seedling requires water. The porous nature of the peat can cause it to dry out faster than the soil within, so checking often is necessary to prevent the material from becoming bone-dry.
The Bottom Watering Technique
The most effective method for watering seedlings in peat pots is bottom watering, which leverages the pot’s porous nature and the physics of capillary action. To execute this, place the pots in a shallow, watertight tray or reservoir, ensuring the tray does not have drainage holes. Next, pour room-temperature water into the tray until the water level reaches approximately one-half to three-quarters of an inch deep. This low water level is sufficient for the pots to begin absorbing moisture.
The peat pot material will draw the water upward through the drainage holes and into the soil mix, similar to how a sponge pulls liquid. Monitor the pots for roughly 10 to 30 minutes, or until the surface of the soil visibly darkens, indicating complete saturation. Once the top layer of the soil is damp, immediately remove the pots from the tray to prevent them from sitting in standing water. Allowing the pots to remain in water indefinitely will lead to waterlogged soil, which suffocates roots and creates an anaerobic environment.
Cautions Against Top Watering
Applying water directly to the soil surface from above, known as top watering, presents multiple problems when dealing with peat pots. A direct stream of water can easily disturb tiny, delicate seedlings and wash away fine seeds that have not yet germinated. Top watering tends to compact the surface of the growing medium, which can create a hard crust that impedes future water penetration and reduces gas exchange to the roots.
Another significant drawback is the tendency for top watering to bypass the pot walls, leaving the rim of the peat pot dry. This dry, above-ground rim acts as a wick, drawing moisture out of the soil and evaporating it into the air. This process dries out the soil faster than if the pot material were consistently moist. While light misting can rehydrate a dry top layer of soil, bottom watering ensures deep, even saturation of both the growing medium and the pot material.
Preventing Watering-Related Issues
Improper moisture control is the primary cause of common problems like mold and fungal growth on peat pots. The presence of a fuzzy white or greenish layer on the pot’s exterior typically indicates excessive humidity or consistently saturated conditions. To prevent these issues, ensure there is adequate air circulation around the seedlings by spacing the pots apart and running a small fan over the area for several hours each day. This gentle breeze helps to dry the surface of the peat, making it less hospitable for fungal spores.
It is important to remove any excess water from the bottom watering tray within an hour of saturation, preventing the pots from continually wicking moisture. If minor surface mold does appear, it is usually harmless to the plant but signals conditions are too wet. Increasing the airflow will help, but a light dusting of ground cinnamon, a natural fungicide, can also be applied to the affected area to discourage further growth. Maintaining this balance between adequate moisture for the seedling and dry surfaces for the pot is fundamental to successful use of peat pots.