She said garden centre sales during the weather-hit start of the year would pick up after the clocks went forward on 28 March.
But she added: "I would like them to be aligned to Europe so people get an extra hour at the end of the day."
An HTA representative said: "Anything that makes daylight hours longer has got to be a good thing if it gives the opportunity for people to get out in their gardens in the evening."
But Richard Dodd from the British Retail Consortium said: "Changing the clocks doesn't produce any more hours of light. It simply re-names the hours so, in practice, would make little difference to retailers. Any gains from lighter evenings would be offset by darker mornings. Switching to another system is not something BRC members have asked us to campaign on."
Plans to change the clocks to give another hour of daylight throughout the year are being advanced by Labour and the Conservatives. Both parties believe it would result in reduced energy consumption, fewer accidents and generally improved health.
The UK moved the clocks forward last weekend to British summertime, one hour ahead of Greenwich mean time (GMT).
Environmental, road safety and tourism campaigners have argued for a switch to GMT+1 in winter and GMT+2 in the summer.
Ben Bradshaw, the secretary of state for culture, media and sport, said the change would be "good for business, good for tourism, good for the environment, improve safety and increase people's sense of well-being".
Carbon reduction pressure group 10:10 have launched a "Lighter Later" campaign, saying that the UK would "be one step closer to a 10% reduction in its carbon emissions, as well as happier, healthier and better off". The move, it argues, would prevent half a million tonnes of CO2 emissions a year. The campaign is being backed by the Royal Society for the Prevention of Accidents (RoSPA).