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White Grano PRR Onion

White Grano PRR Onion


Description: White Grano PRR is a short-day, high-yielding sweet onion variety producing large bulbs (3-4") with low pungency. It has straw-colored skin and white, mild-flavored flesh. It is tolerant to Pink Root Rot (PRR) a fungal disease of onions. 

Origin: Grano Onions were developed from seed originally imported from Spain to Texas in 1925.

Uses: Use raw on sandwiches and in salads. Cooked they are used for adding flavor to any soup, stew or casserole.

Interesting facts: Onions have been used as food, medicine, and even in mummification in ancient Egypt. Ancient Egyptians saw the circular layers as a symbol of eternal life.


General requirements: Short-day onion varieties will form bulbs once daylight hours increase to 10 to 12 hours per day. They are ideal for southern regions of the USA where daylight hours are shorter compared to the longer days up north.   

Soil should be well-tilled, and nitrogen-rich, with a pH of 6.0-7.0. Plants need to be in full sun, and the soil kept consistently moist, but not soggy. Consistent soil moisture is the key to a successful onion crop. Onions have shallow roots, and therefore they aren't efficient at absorbing water. 

When the soil feels dry down to 1 inch deep, it's time to water.

In the garden: Plant onion seeds 6-8 weeks prior to the final spring frost. For a fall planting sow seeds about 4-6 weeks before the first autumn frost. 

Sow seeds 1/4 to 1/2″ deep, 2- 4 inches apart. Or sprinkle generously in a shallow 1” trench, cover with soil and maintain moisture to promote germination. After they have sprouted, snip out the weakest plants and keep the strongest, one onion seedling per 4 –6 inches. Fertilize with fish emulsion or compost tea. Do not feed nitrogen-heavy fertilizer past mid-July.

In containers: For transplanting: Sow onion seeds indoors 8–10 weeks before the average last frost date in your area. Fill a tray or container with good drainage at least 4 “ deep with a dampened seed starting mix. Scatter the seeds then mist them lightly with water. Cover them with ½" seed starting mix. Gently firm the soil with your hand. Keep the seeds warm (70-75°F) and damp until they sprout. You can cover the seeds with plastic to help maintain humidity. Once the seedlings sprout, remove the cover and move the flat to a cooler spot that will get 12 or more hours of bright light each day. You may need to use grow lights. Keep the soil moist and fertilize the seedlings with diluted fish emulsion or compost tea. When they have grown to about 5 inches, trim the greens down to 3 inches. Harden off seedlings before planting. Tease the seedlings apart and plant them in the garden at the same depth as they were in the tray, 3-4" apart.

For growing onions in containers: To raise bulb onions, you'll need a well-draining container wide enough so that each onion has about 3 inches of space around it. Fill it with good potting soil and place it in an area that will get 10-12 hours of sunlight each day. Plant seeds ½"deep, 1” apart. Once the seedlings are an inch or so tall, keep the best-looking plants by snipping out the rest and ensuring that each remaining seedling is 4-6" away from its neighbors. Fertilize with fish emulsion or compost tea. Do not feed nitrogen-heavy fertilizer past mid-July.

Transplanting: Just before the last frost date for your area, trim the greens down to 3 or 4 inches. This will encourage thicker, stronger root development, and prevents the greens from tangling with one another. The trimmings can be eaten so don’t toss them! Gently tease the seedlings apart to plant separately into the garden, spacing them 4-6 inches apart.


Bulbs: Once the plants’ greens have dried out, yellowed, and fallen over, the onions are ready to harvest. Dig them up with a garden fork, or just pull individuals by hand. Brush away loose soil from the bulb and allow the bulbs to further dry. Sweet onions do not store as well as more pungent yellow and brown varieties. Cut away the tops and wrap sweet onions separately in paper towels or newspaper and store in the refrigerator.

Seeds: Onions are biennials which means they flower in their 2nd year. To save seed from onion, select several perfect onions and store them in a cool, dry area until the following spring. Try to replant them at the same depth as when you dug them up. They will begin to send up new growth and eventually a flower stalk. By late summer the flowers, then seed heads will begin to form. As the seed heads dry the seeds will begin to fall out. Remove the seed heads and place them into a paper bag. Shake the bag to release the remaining seeds, then separate the seeds from other debris. 

After assuring that the seeds are dry, store them in a cool, dry place.  


Common name: White Grano onion

Latin name: Allium cepa

Growth habit:

Life cycle: biennial, but grown as an annual

USDA Zones: 2-9, ideal in zones 8 & 9

Seeds per ounce: 8000

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