What pack is this for?
Depending on how agricraft is configured you can try setting up a line of 15 farm blocks in a "U" shape with the initial seed on the 1st block then double crop sticks on the rest.
In packs configured like Regrowth this will allow the crop up upgrade as it proceeds around the "U". 2 trips through and you have a 10/10/10.
Some packs though, line infinity, only allow upgrading between 2 like crops. In this case then time and a watering can is the fastest way to upgrade.
I got everything I needed for beef wellington at 10/10/10 during a 3 hour session. This included cross breading to get the needed crops and upgrading everything to 10/10/10 as I went.