Visually, the trumpet tree (Catalpa bignonioides) is an extremely impressive appearance, especially when the exotic tree has already had a few years under its belt. The strong green, heart-shaped leaves grow up to 20 centimeters long and form lush foliage, which, however, only appears quite late in the year. The orchid-like, white flowers develop into a magnificent sea of flowers between June and July, from which legumes up to 40 centimeters long develop by autumn. These contain seeds that can also be used to propagate the trumpet tree.
How do I grow trumpet tree seeds?
To grow trumpet tree seeds, you should harvest the seeds in spring, stratify them (expose them to cold), soak them in water for 24 hours, sow them in potting soil, keep the substrate moist and let them germinate in a bright, warm place.
Don’t harvest seeds until spring
In contrast to most domestic trees, the seeds of the trumpet tree do not ripen in autumn, but rather in the following spring. You can tell when the time is right by the color of the pods - as long as they are still green, they can remain on the tree. You can start harvesting as soon as the fruits turn brown. This usually occurs between January and March. The very fine seeds inside are flat and have tufts of hair. However, trumpet trees do not develop seeds every summer, and sometimes the pods remain empty. You have the best chances after a very warm and long summer.
Stratification is necessary
Trumpet tree seeds have a germination inhibition that must be broken by a cold stimulus. It therefore makes sense to either leave the fruit pods on the tree over the winter or to stratify the seeds. This is done by placing the seeds, packed in a well-sealed container with moist sand, in the vegetable drawer of your refrigerator for a few weeks. In many cases, purchased seeds are already stratified, so this step can be omitted.
Sowing trumpet tree seeds
The further cultivation works very easily according to the following scheme:
- First let the seeds soak in lukewarm water for 24 hours (change several times!).
- Sow them in a planter with potting soil and cover them lightly with substrate.
- Keep the substrate evenly slightly moist.
- Place the potty in an indoor greenhouse (€24.00 on Amazon) or cover it with foil.
- The planter is best kept in a bright and warm place.
- Ventilate several times a day.
The very germinative seeds often show their first delicate green after just a few days.
Tip
If trumpet trees feel comfortable in their location, they tend to self-propagate through seeds or planters.