Favourite garden varieties include, Helleborus foetidus, Helleborus niger and Helleborus hybridus, says the HTA.
The association says linked sales include snowdrops, primula, and pulmonaria and complementary plants like cornus and mahonia.
TV gardener David Domoney is the celebrity champion for Helleborus this month.
He said: "Flowering Hellebores make you wonder at the beauty and resilience of nature as they open beautiful flowers in the depth of winter. The diversity of the colour and blooms together with integrated shaped emerald green foliage across many varieties make this a perfect first choice as the calendar year starts".