Growing a cedar tree from seed is a slow process that requires patience and attention to detail. Cedar trees, especially the true cedars (Cedrus species), are known for their longevity and impressive size. This guide provides a step-by-step approach for home growers to successfully navigate the journey from seed to established sapling. Seed preparation is the most important step, as it overcomes the natural dormancy mechanism.
Sourcing and Pre-Treating Cedar Seeds
Sourcing fresh, viable seeds is important, as their ability to germinate declines quickly after harvest. True cedar seeds, such as those from the Cedar of Lebanon (Cedrus libani) or Deodar Cedar (Cedrus deodara), are typically collected from mature cones in the autumn. After extraction, gently rub off the thin wings attached to each seed using a dry cloth.
Cedar seeds possess a natural dormancy that must be broken before they will sprout, mimicking the cold, moist conditions of winter. This process, known as cold stratification, is necessary for germination. To stratify, first soak the seeds in warm water for 12 to 24 hours to initiate water absorption. Then, place the seeds in a sealed plastic bag with a slightly moist medium, such as sand, peat moss, or a paper towel, ensuring the medium is damp but not soaking wet.
The sealed bag should be placed in a refrigerator, maintaining a temperature between 34 and 41 degrees Fahrenheit (1–5°C). For many true cedar species, the required cold period ranges from 30 to 90 days, though some varieties may only need about two weeks. Check the seeds periodically for mold; if seen, clean them and return them to a fresh, slightly damp medium. This chilling period prepares the seed for spring growth.
Sowing the Seeds for Germination
Once cold stratification is complete, typically in late winter or early spring, the seeds are ready to be sown indoors. Use a sterile, well-draining seed-starting mix to prevent fungal diseases. A mixture of half potting soil and half perlite or sand works well to ensure adequate drainage.
Shallow containers like seed trays or individual pots with drainage holes are suitable for initial planting. Plant the pre-treated seeds at a depth of about one-quarter to one-half inch (6–12 mm) and lightly cover them with the medium. After sowing, gently water the soil from the bottom or use a fine mist to settle the medium. Consistent moisture is necessary during this stage.
Initial Care for Cedar Seedlings
After sowing, place the containers in a warm environment, ideally maintaining a temperature around 68°F (20°C). Cedar seedlings need bright light to develop properly. This can be provided by a south-facing window with indirect light or by using a dedicated grow light positioned a few inches above the emerging plants. Insufficient light results in weak, spindly growth.
Proper watering prevents “damping off,” a fungal disease that thrives in overly wet conditions. Keep the soil consistently moist but never saturated or waterlogged. Do not fertilize seedlings immediately, as the seed contains enough nutrients for initial growth. Wait until the seedlings have developed their first set of true needles, usually after several months, before introducing a balanced liquid fertilizer.
Transplanting and Establishing Young Trees
When the young cedars reach one to two inches in height and have been in their initial containers for several months, transplant them into larger, individual pots to encourage root development. This move typically happens in early summer, before the trees are moved outdoors. Before permanent planting, they must undergo a gradual process called “hardening off.”
Hardening off acclimates the indoor-grown seedlings to outdoor conditions of wind, full sun, and temperature fluctuations. Over one to two weeks, place the seedlings outside for increasing durations each day, starting with an hour in a shaded, protected location. Gradually expose them to more sun and wind until they can tolerate spending 24 hours outdoors without stress.
The young trees are ready for their permanent location in the fall, or the following spring, when they are at least one year old. Choose a planting site that offers well-draining soil and accounts for the mature size of the cedar. When transplanting, disturb the root ball as little as possible to minimize shock. Water the young tree regularly for the first few seasons to establish a strong root system.