When the grape hyacinth flowers begin to fade, their flower heads should be plucked off before they start to produce seeds. In this way, the bulb is given more strength to grow, or to propagate through offset bulbs. If grape hyacinths are intended to grow wild and seed, leave the flower heads on the plant.
As soon as the leaves of the grape hyacinth become yellow and finally dry up, they no longer need watering. Once all the leaves of the plant are then brown and dry, it is time to cut back the grape hyacinths. Many garden owners are not aware that their grape hyacinths have to be cut back: Once the long and grass-like leaves have dried up and turned yellow, they are trimmed to approximately 2 cm above the earth. It is important that the leaves are not trimmed prior to them going yellow, as plants up to this point nutrients are still being recycled from these leaves for growth the next spring.
Because when cutting the leaves, the old flower stems and seed capsules with their ripened seeds are cut off, we recommend that you work in two steps: first harvest the seed capsules and spread the seeds, and then remove the old leaves from the bulbs.
Although the grape hyacinth is considered highly robust and resistant, it is not protected against all diseases. If the plant is growing in an unsuitable location, or if the individual bulbs are planted too densely, smut fungi may occur. This mainly affects the flower heads. If the flowers are attacked by such a fungi, it is advisable to remove the affected parts and to put them in the waste bin – not on the compost. In order to prevent smut fungi, the grape hyacinths can be treated with field horsetail brew to strengthen them.
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