A growing number of outdoor house plants have been found to have indoor properties in Australia, a new study has found.

In a study published online in the Australian Journal of Botany, researchers found the indoor plants in most of the indoor plant species they studied were in fact living on the soil surface of their owners.

Indoor plants like garden plants, shrubs and perennials are known to be rich in nitrogen-rich soil.

Nitrogen is vital for plants to survive and thrive, and is a byproduct of photosynthesis, which allows plants to produce sugars for their own energy.

But for many plants, nitrogen can be a problem.

Nitrogen is often used to produce nitrogen-fixing compounds called nitrogen-based fertilisers.

In the study, researchers from the University of Sydney and the University at Albany found that most indoor plants that were considered ‘living’ in their owners’ gardens contained levels of nitrate and phosphorus in their soil that were more than 30 times higher than what would be expected in a natural environment.

This was the case even for the plants considered to be ‘dead’ and in the vegetative state.

The authors of the study said their findings suggested that living plants were actually living on top of their garden soil.

This is a common feature of many indoor plants, which may help them to thrive on the land, the authors wrote.

The researchers said they had also identified some species of plants that may be able to tolerate the nitrogen levels in their soils.

But their study did not consider whether these plants would need to grow in a garden or to be cultivated indoors.

It is important to note, however, that there is no evidence that indoor plants are more prone to nitrogen deficiency than outdoor plants, said the study’s lead author, Prof Daniel Kober of the University’s School of Agriculture.

This makes it difficult to determine the health of indoor plants and the best strategies for managing their nitrate levels.

The findings are particularly concerning for those with indoor allergies and sensitivities, or who live with chronic illnesses, Prof Kober said.

The study has implications for people with allergies or sensitivities to indoor plants.

Prof Kober is a specialist in indoor plants at the University, and the study was funded by the Australian Government’s National Science and Engineering Research Council.

He said he had been working on the study for a long time, and that it was the first time he had seen such an issue.

“Nitrate and nitrogen levels are a big issue in indoor gardens, because indoor plants don’t produce enough nitrogen-containing nutrients for themselves,” he said.

“If you’re going to grow plants in a home garden, it’s important to know whether you’re growing indoors or outdoors, so we’re trying to understand what is happening in the environment of the plants.”

The study’s findings may help explain why indoor plants can be so difficult to grow, he said, but it is important that gardeners were aware of the potential for soil nitrogen and nitrogen-related problems to be encountered in their gardens.

It’s not known whether these indoor plants have nitrogen-dependent diseases, but a growing body of research suggests there are environmental triggers for the growth of indoor pests, and indoor plant diseases are common, he added.