Field maple trees (Acer campestre) are a common sight, known for their robust nature and distinctive seeds. These seeds, formally called samaras, are widely known by charming nicknames such as “helicopters” or “whirligigs” due to their unique winged structure that allows them to spin gracefully as they fall from the tree. The presence of these winged fruits in autumn signals the tree’s reproductive cycle, offering an opportunity for those interested in cultivating their own field maples from seed.
Identifying Field Maple Seeds
Field maple seeds possess distinct physical characteristics that aid in their identification. Each seed is a winged fruit, specifically a samara, and they invariably appear in pairs, joined together.
A key identifying feature is the angle at which these wings are set; they typically extend in a straight line from each other, forming a 180-degree angle. This horizontal alignment differentiates them from the seeds of other maple species, such as sycamore, whose wings are often at a more acute angle, around 45 degrees.
The appearance of field maple seeds changes as they mature through the season. Initially, when immature, the seeds can display shades of green, often with noticeable pink or reddish tinges. As the seeds ripen and dry, their color transitions to a straw-like tan or a light brown, indicating their readiness for dispersal.
Each samara measures between 2.5 to 3 centimeters in length, with the nutlet comprising less than half of this measurement; the remainder is the papery wing for wind dispersal. The surface of the nutlet often has fine hairs, contributing a subtle, pubescent texture.
Collecting Field Maple Seeds
The optimal period for collecting field maple seeds is during late summer to early autumn, typically spanning September through October. At this time, the seeds should have turned brown and feel firm and full to the touch, indicating they are ripe and ready for collection. While collecting, it is important to select healthy, intact seeds directly from the tree or from the ground beneath it.
When gathering seeds, it is advisable to collect a generous quantity to account for potential losses during preparation and germination, but always remember to leave a sufficient amount for local wildlife. To store the collected seeds temporarily, cotton or hessian bags are recommended, as they allow for air circulation and prevent the seeds from sweating, which can lead to damage.
Upon returning from collection, spread the seed bunches in thin layers in a dry, room-temperature environment to allow them to dry further and naturally separate. Once separated and dried, the seeds can be stored in sealed plastic bags, ideally in a cool, dry place like a refrigerator, until they are ready for the next steps.
Preparing Field Maple Seeds for Planting
Field maple seeds exhibit a deep dormancy, which necessitates specific preparation steps before they will germinate reliably: warm pre-treatment followed by a cold stratification period. To begin the process, soak the cleaned seeds in room temperature water for 24 to 48 hours. This initial soaking helps to rehydrate the seed and can begin to soften the seed coat.
Following the initial soak, a warm stratification phase is recommended. Mix the seeds with a moist, free-draining substrate (such as a 50/50 blend of compost and sharp sand, or alternatives like perlite or vermiculite). Ensure the substrate is moist but not waterlogged; if squeezed, no water should drip out. Place this mixture into a clear plastic bag, such as a zip-lock bag, leaving a small opening for air exchange, and keep it at approximately 20°C (68°F) for at least eight weeks. It is important to prevent the medium from drying out during this period.
After the warm phase, the seeds require a cold stratification period. Transfer the prepared seed mixture to a refrigerator, maintaining a temperature around 4°C (39°F) or within a range of 1-8°C. This cold treatment should last for approximately 24 weeks. Checking the bag periodically, perhaps every 7 to 10 days, is important to ensure the medium remains moist and to look for any signs of mold or premature germination. If seeds begin to sprout in the bag during this cold period, they should be carefully removed and planted immediately. Seeds that are ready for planting will appear plump and soft.
Planting and Growing Field Maple Seeds
After the necessary stratification period, field maple seeds are ready for planting, ideally in the spring. Prepare a well-draining soil mix for sowing; a blend of 40% garden soil, 30% coarse sand, 20% compost, and 10% perlite provides a suitable environment. Alternatively, a good quality potting soil can be used.
Sow the seeds thinly, covering them with approximately 10mm (1 cm) of coarse horticultural sand, grit, or compost, or a depth of about 0.25 to 0.75 inches (0.6 to 2 cm). Once planted, consistent moisture is important for the newly sown seeds and emerging seedlings. Keep the soil continuously moist, but avoid overwatering to prevent rot.
Field maple seedlings thrive in locations that receive full sun to partial shade. Protecting them from extreme temperatures is important, as high heat (above 25°C) shortly after sowing can induce secondary dormancy, delaying or preventing germination. As the seedlings grow, typically reaching a few inches in height, they can be transplanted into larger pots. Allow them to develop for one to two years in these pots before considering their permanent placement in the garden.