Beginning gardeners have often wondered what all of those light green, bumpy growths are that show up on a star magnolia tree (Magnolia stellata) in late summer. They might look like mere bumps (weird growths that may cause a novice to worry that the tree has a problem), but they are not.
Those bumps are actually star magnolia seed pods. As long as the star magnolia seeds remain inside, the pod appears to be little more than a curious, amorphous mass. But in late summer (September in USDA plant hardiness zone 5), the orange seeds begin to burst out, helping us to identify the bump as a seed pod. Wild birds eat the seeds, which are loaded with nutritious fat.
Gardeners should not become complacent, though: The bumps on some plants truly are growths, not seed pods. An example is provided by the bumps that sometimes appear on azalea shrubs.
What Other Magnolia Seed Pods Look Like
Of course, other types of magnolia trees also have seed pods, and they can look quite different from those on a star magnolia tree.
The red color of the seeds in Southern magnolia seed pods is just as striking as the orange color of the seeds borne on a star magnolia. Wild birds, squirrels, and other animals eat the seeds.
Star magnolia seeds are not toxic to humans, nor are they poisonous to pets (either cats or dogs). Likewise, closely related magnolias widely grown in Northern yards, such as Magnolia x soulangiana, are safe to grow around kids and pets.
The seeds of Southern magnolia are mildly poisonous if eaten by humans (the wild birds and the squirrels do not seem to be adversely affected). Magnolia grandiflora is poisonous for cats, too. While toxicity information is hard to find regarding dogs eating the seeds, it is always better to err on the side of caution.
Another Magnolia Family Member: the Tulip Tree
Tulip trees (Liriodendron tulipifera) are associated with magnolia trees through family ties, a connection easily detected if you inspect the flower. Happily, this wonderful shade tree with yellow fall foliage is not toxic either to animals or to humans. The seeds are not colorful, being a drab tan.
How to Start a New Magnolia Tree From Seed
Gardeners who grow magnolia trees sometimes find that a seedling has sprouted in the landscape. If given the proper conditions, this seedling will eventually become a magnolia tree in its own right. You should keep a couple of warnings in mind, though:
- It will take a long time for the plant to make the journey from seedling to a flowering tree.
- If you want to collect the seeds and take over the propagation process from Mother Nature, you will not get far unless you keep in mind a trick employed by horticulturists, a term that refers to those who study horticulture.
Regarding this second point, not all of the steps required to start a new magnolia tree from seed will be intuitive for beginners. Here is a summary of the propagation process as detailed by Stefan Cover via the International Dendrology Society:
- Wait for the pods (cones) to open. Do not force the seeds out prematurely, but do not wait too long either (it's bad to have the seeds dry out completely while still in the pod).
- Soften the orange outer coating on the seeds by soaking them in water for several days.
- Wash off the now-loosened coating using soapy water.
- Lay out the seeds to dry a bit overnight.
- Put the magnolia seeds in a sealable plastic baggie filled with moistened peat moss.
- Stratify the seeds. This entails putting the baggie in the refrigerator "for at least 60 days." It is through this "stratification" (subjecting the seeds to the cold) that you get the seeds ready to germinate.
- In spring, take the baggie out of the refrigerator. Spread the contents (both peat moss and seeds) onto a seeding tray, and keep them where it will be 70 to 75 degrees Fahrenheit.
- Keep the peat moss moist, but not soggy.
- At germination (which should take "5 to 14 days"), transplant the seedlings into pots that have been filled with a potting mix.
- Put the pots in a South-facing window and keep the potting mix moist, but not soggy.
- Transplant the seedling outdoors once all risk of frost is over.