I found this info
Propagation:
Burdock is grown from
seed. Sow Burdock
seeds in your garden as early as the ground can be worked. Cover
seeds with 1/2" to 3/4" of fine garden or
seed starting soil. Tamp soil. Water lightly, if the soil is dry.
seedlings germinate quickly, in about 4-7 days.
How to Grow Burdock Plants:
Burdock is easy to grow. It grows readily in the wild, without day human assistance. The attention you provide to it in your garden, will promote bigger, deeper roots, and more plant and
seed to harvest. Burdock likes full sun, but will tolerate partial shade.
The soil should be rich, and drain well. The most important characteristic of the soil, should be loose and free of rocks and stones up to a depth of a couple of feet. This allows the roots to grow long and straight.
After
seedlings have grown a few inches, thin to 3" apart in rows two feet apart.
weed frequently, especially when plants are young.
Keep soil moist. Apply a general purpose fertilizer once a month.
Did you Know? The roots of some varieties of Burdock can grow four feet long. Some plant varieties can grow up to nine feet tall.
Keep
flowers and burrs picked, to promote growth of plant and root.
Tip: Fewer leaves allow denser plants and a higher yield. If you are
growing Burdock just for the roots, prune some leaves as the plant grows.
Harvesting:
Pick leaves and tender young stems for eating fresh. Cook like spinach.
Roots take a long time to grow, over 100 days. Pick when roots are one to two feet long. Peel and eat raw or cooked. Use in soups, salads, and stir fries.
Insect and Disease:
Insects can be an occasional problem. Treat with insecticide or repellents, as needed.
I believe you will find daikon very similarly grown.
Good luck on your wife's illness and recovery.