Nathan Greenway's legal team believe he had touched the poisonous wild plant Aconitum napellus, also known as Monkshood, at Mill Court House, Alton.
The 33-year-old, from Aldershot, died in hospital five days later on 7 September from multiple organ failure.
The pre-inquest hearing in Basingstoke was adjourned until a date yet to be fixed.
North East Hampshire Coroner Andrew Bradley said the circumstances surrounding the death would be investigated at the full inquest.
Mr Greenway worked on the estate in Upper Froyle.
Mill Court House is owned by Christopher William Ogilvie Thompson and his wife Kathy.
Their legal team declined to comment.
What is aconite?
The Aconitum napellus plant has dark purple flowers and often grows in gardens in Europe.
Poisoning from aconite is rare and usually happens when the plant, also known as Devil's Helmet, is eaten accidentally.
Symptoms of aconite poisoning appear quickly after a poisonous dose is consumed. These include nausea, vomiting and diarrhoea and numbness of the face.
In severe cases, the numbness can spread to the limbs and muscles can weaken. It also causes hypotension, chest pain and palpitations.
It can cause abnormal rapid heart rhythms and can stop the heart from beating.
Source: Clinical Toxicology journal
A gardener died after apparently handling a deadly plant on an estate in Hampshire, a coroner has heard.