Harvesting your own grass seed is a practical way to manage your lawn and secure a supply of a specific grass type for future propagation. This process allows homeowners to save money on commercial seed and maintain their desired turf variety. Collecting seed from existing, healthy grass plants requires proper timing and basic post-harvest techniques. This effort often ensures genetic purity or naturally thickens a lawn with seed adapted to the local environment.
Determining When to Harvest
The timing of the harvest directly influences seed viability. Grasses require 20 to 30 days after flowering to reach full maturity. For many cool-season grass varieties, this window typically occurs from mid-July through late August, depending on the local climate.
A visual change in the seed head color is the first indicator that the seeds are approaching ripeness, shifting from bright green to a tan, orange, or golden hue. Since grass heads ripen unevenly, it is necessary to test individual seeds for firmness. The preferred stage for harvest is the “hard dough” stage, which precedes the seed becoming fully dry and prone to shattering.
The difference between the “milk stage” and the hard dough stage is determined by a simple squeeze test with a thumbnail. If the seed is soft, it is in the milk or soft dough stage, meaning it contains too much moisture and will shrivel. Seeds ready for collection will be firm and require moderate pressure to dent, indicating the embryo is fully developed. Another field test is the shatter test: gently striking the seed head against your palm should cause only a few seeds to fall. If the seeds easily detach, the harvest is ready and should be completed immediately to prevent loss.
Techniques for Collecting Grass Seed
Once the seed is ready, the collection method should be chosen based on the area’s size and the amount of seed required. For small patches or selective collection, manual methods offer the greatest control. Clipping the seed heads just below the bottom of the inflorescence with scissors or hand shears and placing them into a collection bag is a precise, small-scale approach.
The hand-stripping method is another effective manual technique, especially for grasses that hold their seed loosely. Wearing gloves, gently run your thumb and index finger upward along the stem of the flowering head. This action strips the ripe seeds into your gloved hand or directly into a container held underneath.
For larger areas, a modified lawn mower with a bagging attachment provides a mechanical alternative. The mower deck should be set to its highest possible setting to cut only the seed heads while minimizing damage to the remaining grass blades. This method collects a mixture of seed, chaff, and stem material, which requires more intensive cleaning later. An alternative is using specialized hand-held seed-stripping tools, such as a plastic comb or brush, to dislodge the seeds into a trailing receptacle.
Post Harvest Processing and Storage
After collection, the material must be dried and cleaned immediately to prevent mold and maintain seed viability. Freshly harvested grass seed material often has a high moisture content, which is far too high for safe storage. The collected material should be spread thinly on a sheet or screen in a cool, dry, and well-ventilated area for several days to allow the moisture content to drop.
Once the material is thoroughly dry, the seeds must be separated from the surrounding plant debris in a process called threshing and cleaning. Threshing can be done by rubbing the dried seed heads vigorously between your hands or walking on the material spread out on a tarp. This action breaks the seed heads apart, releasing the individual seeds from the chaff.
Following threshing, the material needs to be cleaned through a process known as winnowing. This involves using a fan or natural wind to blow away the lighter chaff and debris from the heavier, viable seeds. The seed should be slowly poured from one container to another in front of the airflow, allowing the lighter material to be carried away. The goal is to reduce the seed’s moisture content to a safe level (typically 8% to 12%) for long-term preservation. Finally, the cleaned, dry seed should be stored in an airtight container, such as a glass jar or plastic tub, labeled with the date and grass type. Storing it in a cool, dark, and dry location maximizes shelf life and germination potential.