Hay, will you marry me?

Harnessing the humble language of straw, Clinton had used about 75 hay bales to spell out 'Marry Me Casey' on her family farm just out of Wynarka, which was revealed to Casey when the pair flew above the farm on their six-year anniversary.

"I woke up that morning and thought I was going to work but no, Clinton said he had organised a day off for me and that I had an hour to get ready," Casey said.

"It was just before Christmas last year, and so Clinton said we were going up in the air to fly across the top of Mum and Dad's farm to take some videos for them, so I didn't really think anything of it."

Casey said she was talking to the pilot about the landmarks on the farm when she spotted the newest and perhaps most impressive landmark of all.

"I was pointing everything out, and then I saw it. I kept saying 'is this for real', I really was in shock," she said.

The fact that the proposal happened on the family farm - albeit a few thousand feet above it - was very special for Casey.

"My Dad helped organise it all, I'm pretty close with my Dad so it was really special that he was involved, and my whole family played a part," she said.

Casey said Clinton was originally going to just write 'marry me', but thought he had better add her name onto the end just in case.

As for adding a question mark, Clinton wasn't interested.

"Everyone was giving me stick about not putting a question mark on the end, but by the time we'd finished it was dark, so it ended up being a statement rather than a question," he said.

"Casey" took a taskforce of four people four hours to write, with Casey's dad Jack Gregory spending the previous day and a half using a loader to write 'Marry me'.

The preparation for the grand gesture was three months in the making, between designing a ring, organising the hay bales and sorting out the logistics.

"At the start of last year I was waiting and waiting for a good time and then I basically woke up one day and thought 'I'm going to do it', so I went to Adelaide and designed a ring," he said.

Clinton said the initial idea was to use line-marker paint, but the dry ground meant the writing blew straight off.

"I did a test patch with the paint, and the next day it was gone, the top of the sand had been blown off. So I ended up choosing the greenest paddock I could and using hay bales."

But things didn't go completely to plan on the day, with the plane flight being delayed until about 2pm, after take-off was originally scheduled for mid-morning.

"We were meant to go up straight after breakfast but we couldn't take off because the visibility was really bad. The pilot kept texting me saying we had to wait another hour, another hour, so I had to keep coming up with things to do."

Jack Gregory said his daughter's keen eye for detail caused problems in the lead up.

"The hardest thing was keeping it a secret from Casey," Jack said. 

"She would come out to the farm on weekends and ask me why I hadn't stacked the hay up properly... well I did initially have it stacked up and had then unstacked it, but of course I couldn't tell her that. Luckily from the ground you couldn't tell what it was."

Jack was thrilled with how the proposal unfolded.

"It was a really special moment," he said.

"A few weeks beforehand we got a bit of rain, and so there was a green tinge to the paddock which made the setup look even better."

Jack was wary that when it came to the wedding itself, the proposal would be hard to beat.

"I'm copping a fair bit of pain from everyone that we've set the bar way too high," he said.

"I don't know how we're going to top that - I think maybe the wedding should just be a backyard barbecue."

Contradictory to this laid-back plan, the couple will be wed at Mt Lofty House on February 29 next year.