Conservationists are urging people not to carry out "frogspawn-swapping" this spring because of problems they say it can create for the pond environment.
Frogs are welcome visitors to many gardens across the UK
Wildlife-lovers in the UK often donate frogspawn from their ponds to others to give frogs a potential new home.
But the Froglife charity said this could lead to the spread of invasive plants and harmful diseases.
Scientists say the best way to populate ponds is by making them frog friendly and letting nature take its course.
Conservationists at Froglife said the practice of spawn-swapping in the UK goes back decades.
They believe it is one of the reasons frogs have remained widespread in this country.
A survey of about 1,000 people by the charity suggested a third of them had artificially moved frogspawn into their own ponds when they had created them.
But the trade in pond plants is now global and people may get more than they actually intended if they took frogspawn from a neighbour's pond or a local lake, Froglife warned.
They could, for example, be importing the highly invasive Australian Swamp Stonecrop, a plant that forms dense carpets, which block sunlight.
And a number of harmful plants can also be transferred in the water with frogspawn, including parrot's feather, water fern and floating pennywort, which are all invasive species.
Froglife said that if the common frog, widespread in the UK, moved of its own accord, diseases were likely to spread more slowly and less widely, while non-native plants would not take hold and threaten ecosystems in new habitats.
The charity said wildlife-lovers should not worry that there is too much frogspawn in their ponds, because frogs lay thousands of eggs on the basis that only the strongest handful will survive to breed.
The charity also warned that selling frogspawn, tadpoles or frogs in the UK is illegal and it monitored internet auction sites each spring to ensure the law was not being broken.
Froglife said there was research to suggest frogspawn can carry a disease passed down from adults called ranavirus.
This is relatively new to the UK and has killed thousands of frogs each year since emerging in south-east England in the late 1980s.
Daniel Piec, head of conservation at Froglife, said: "Sadly, moving frogspawn around often serves only to heighten the risk of moving around invasive plants and diseases that have potential to do real harm to frogs and other pond-inhabitants.
"If you want to do the best for our wildlife, our advice is to leave frogspawn where it is and let nature do the rest."