The best time to plant dahlias in pots is in early spring, typically in March or early April. At this time, dahlia tubers can be planted in large pots filled with peat-free, multi-purpose potting compost and kept indoors on a sunny windowsill or in a frost-free greenhouse. This allows the plants to start growing earlier in the season. The dahlias can then be moved outdoors or kept inside once the risk of frost has passed, usually in late May or early June, depending on the local climate. This approach helps dahlias to develop faster and often results in earlier flowering compared to planting directly outside later in the season.
Planting instructions specific to pots include:
- Using pots of at least 12 inches deep and 16 inches wide, with good drainage.
- Positioning the tuber in the pot with the buds or shoots facing upwards and covering lightly with compost.
- Keeping the pots in a warm, sunny, and sheltered spot indoors or greenhouse until frost danger passes.
- After plants grow about 10-14 inches tall, they can be hardened off by placing them outside during the day for a week before final outdoor planting.
In summary, start dahlias in pots indoors or in a greenhouse from March to early April and transplant or move outside after the last frost in late May or early June.
