Growing Actinidia deliciosa or Actinidia chinensis, the common kiwi varieties, from seed is a long-term horticultural project. The kiwi is a vigorous, climbing vine, not a tree. While propagation is often done via cuttings to ensure desirable traits and gender, growing from seed offers a unique genetic lottery. This process demands patience, as the time from seed to fruit can span several years.
Extracting and Preparing Kiwi Seeds
The first step involves harvesting viable seeds from a ripe kiwi fruit, preferably an organic one. Begin by slicing the fruit and gently scooping out the pulp that contains the tiny black seeds. Avoid using a blender, as the blades can damage the delicate seeds, reducing their viability.
The seeds must be thoroughly cleaned to remove all traces of fruit pulp and sugar, which can cause mold or fungal growth during germination. Rinse the pulp and seeds under cool running water, using a fine-mesh sieve or coffee filter to separate the seeds from the sticky material. Non-viable seeds often float, allowing you to discard them easily.
Once cleaned, the seeds must be dried before storage or preparation. Spread the seeds on a paper towel and allow them to air-dry for one or two days. This removes any remaining moisture before beginning the necessary process of cold stratification.
The Seed Germination Process
Kiwi seeds require cold stratification, a process that mimics the natural cold and moist conditions of winter, to break their dormancy. Without this chilling period, germination rates are significantly lower. A common method is to place the cleaned seeds on a damp (but not soggy) paper towel or mix them with sterile, moist peat moss or sand.
Place the paper towel or medium inside a sealed plastic bag or container to maintain humidity. Store this container in a refrigerator, ideally between 33 and 41 degrees Fahrenheit, for approximately three weeks. The medium must remain constantly moist during this time, so check it periodically to prevent drying out.
After stratification, sow the seeds in a sterile seed-starting mix in a shallow tray or pot, covering them with only about 1/8 inch of soil. Mist the surface liberally to settle the soil around the small seeds. Place the container in a warm location, ideally around 70 to 75 degrees Fahrenheit, and watch for sprouts to emerge over the next two to three weeks.
Caring for Seedlings and Initial Transplanting
Once the kiwi seedlings emerge, they need sufficient light to begin photosynthesis and develop their first true leaves. Place the tray in a bright, south-facing window, or position them under a dedicated grow light set to run for 12 to 18 hours per day. Insufficient light can cause the seedlings to become leggy and weak.
The soil must be kept consistently moist, but never waterlogged, as the delicate roots are susceptible to rot. Watering with a gentle mist or from the bottom up is the best approach to avoid dislodging the small plants. As the seedlings grow, thin them out, leaving only the strongest plant every couple of inches, or separate them into individual pots.
The first transplant should occur when the seedlings have developed a few sets of true leaves and are large enough to handle. Carefully move each seedling into its own pot containing a well-draining potting mix. Before moving them permanently outside, the young plants must be “hardened off” by gradually exposing them to outdoor conditions, like direct sun and wind, over one to two weeks.
Long-Term Plant Care and Understanding Fruiting
Kiwi vines are vigorous climbers that require substantial structural support, such as a sturdy trellis, pergola, or wire system, as they can grow up to 30 feet long. They thrive in a sunny, sheltered location with rich, loamy, and slightly acidic soil that is consistently moist but well-drained. Mulching around the base of the vine helps retain soil moisture and suppress weeds.
Plants grown from seed are genetically unique, and their sex is unknown until they flower, which typically takes five to eight years. Kiwi plants are dioecious, meaning they produce male and female flowers on separate plants. Only the female plant will bear fruit, and it requires pollen from a male plant for successful pollination.
To ensure fruit production, you must have at least one male vine for every five or six female vines in close proximity. Growing from seed is a commitment to a long-term gardening endeavor due to the long wait time and the need for both sexes. Regular pruning is also needed in the winter to manage the vine’s size and encourage fruit production on the one-year-old wood.