Growing a gardenia from seed is a difficult task, but because of this it is a very satisfying accomplishment. Gardenias need specific environmental features and care in order to survive and be healthy.
Preparing to Grow Gardenias
Not every location is appropriate to grow gardenias. They require daytime temperatures of 70 to 75 degrees F, and nighttime temperatures of 60 degrees F. Temperatures outside this range can cause a gardenia to not flower, or die
Gardenias require soil with good drainage, acidic soil and high humidity. If you cannot provide your gardenia with these things, either naturally or artificially, you may want to choose a different plant to grow.
You can get a soil mix specifically designed for gardenias at your local nursery. You will also need some flat trays for seedlings.
Sowing seeds in trays is the best way to begin planting gardenias. In addition to their temperature and humidity requirements, they need a reasonable amount of water. Keep their soil moist. Gardenias grow very slowly and unpredictably, so the amount of time to reach the next step may vary, but be patient. It's important that your seedlings grow large enough to survive transplanting.
Once the gardenias grow their third leaf, transplant them to small pots. Remember, your gardenia needs plenty of bright light, but keep it out of direct sunlight
Transplanting seedlings a second time is the next step. When they outgrow their pots, transplant them to a bag that you can use to transfer them to your garden.
The gardenia's shallow roots cause it to be vulnerable to weeds. It is much better for your plant to avoid them altogether with a layer of mulch. This also helps keep your plant's soil moist.
During the growing season, between April and November, there are a number of things you can do to help your gardenia stay healthy. You should fertilize your gardenia at this time to encourage flower growth. Use a fertilizer formulated for plants that like to grow in acidic soils. Apply every four weeks. Too much fertilizer is worse than too little. Watch for yellowing lower leaves. If you see them, you can give your plant a little bit of magnesium sulfate (also known as epsom salts or bitter salts) to clear up this problem. Only do this once a year. No matter what you add to your soil, it is a good idea to flush the soil regularly with water to avoid buildup of harmful chemicals, fertilizer, and salt.
Outside of the growing season, your gardenia will still require care. You will need to prune the lowest branches - any that are in danger of touching the ground, as this can lead to infections. Doing this while your plant is dormant allows it to heal more efficiently, instead of wasting its energy that should be spent on flowering.