B&Q's top 10 tips for inexperienced gardeners to help garden wildlife are:
1 - Tweet your discoveries
2 - pop up a bird cafe
3 - plant for pollinators
4 - give wildlife some shelter
5 - shop nature savvy
6 - build a pond or bird bath
7 - help wildflowers grow
8 - plant trees and shrubs
9 - open hedgehog gateways in your fence
10 - make your cat be safe and seen to reduce threats to wildlife.
A YouGov/B&Q survey found 67% of people are concerned about British wildlife. It found gardens house thousands of species including 45 UK priority species, using Jennifer Owen, Wildlife Gardening Forum and Natural History Museum figures.Hedgehogs, sparrows, toads, moths, stag beetles and cornflowers are among priority species.
Pollinator declines "are of real concern" and can be helped by planting flowering plants such as lavender, even in small gardens, window boxes and doorsteps.
Some 83% of the UK population live in towns and cities where gardens make up a quarter of the total area. Some 63% said there are benefits for us by bringing more nature into gardens.
More birds (71%), pollinators (59%), and hedgehogs (59%) were priorities. Half households feed birds and 28% use feeders. There are about 3m ponds and 29m trees.
But lack of time (24%), money (23%), knowledge (23%) and space (22%) were seen as barriers.
And 20% said they did nothing to help wildlife in their gardens. There are 28.5m homes and 24m gardens in the UK. Average size garden is 190sqm. In all they cover 500,000ha. But new homes' gardens average 113sqm and 26% don't have gardens, up from 18% in 1996.
B&Q recommend using no peat, cutting use of power tools, chemicals such as neonicotinoids and tap water and tackling "the sensitive issue" of cat predation of birds and mammals using bells or collars.
B&Q sustainability manager Rachel Bradley said: "Until we commissioned this report we didn't realise quite how important our gardens could be for nature."
Report partner was Bioregional. RSPB, RHS, Wildlife Trusts and Butterfly Conservation reviewed the report.
State of Nature 2016 found a 67% decline in population for 213 of the UK's most threatened species since 1970.
Meanwhile, the RHS has launched a report reiterating that artificial lawns, plants from arid countries and flower beds designed to cope with floods will be among future features of UK gardens as climate change kicks in.
Dr Eleanor Webster coordinated the report. She said the south of England is going to be hotter and drier throughout the year with some heavy rain showers and the north of England is going to be milder but it is also going to be wetter in the summer and in the winter. This means water conservation will be more important in the south, while managing a wet and warm environment will be essential in the north.
The report says the most recent decade being 0.9C warmer than the period 1961-1990 and to an increase in rainfall over Scotland and the north of England over the past century.
The report's authors say by 2100 the West Country will have an average temperature 3C higher than now with heavy winter rain and more frequent storms.
Many lawns there will become woodland or shrub because mowing would have to be year-round and because it is difficult to mow turf that is water-logged.
Smaller trees will replace larger ones which are more vulnerable to being blown down in strong winds. And slopes will have to be cut with terraces to stop soil erosion.
In East Anglia 2100 an average temperature could be 5C warmer than now. Lawns will be replaced by synthetic grass.
Rain will be stored in underground tanks. Garden centres will pre-condition plants to become used to drought. Shade will come from almond, peach and olive trees.
For the north of England, 2100 could be 2C warmer with more winter rain, more extremes and more violent storms,needing more robust plants.
The RHS recommends irrigated raised beds to help with draining heavy rainfall and planting buddleia and clematis in the north and aloe and eucalyptus in the south.