Prepare before you plant your onion transplants

While the enclosed plants may appear dry, don’t be alarmed; they’re simply dormant. Don’t worry if you can’t plant them immediately, even if the roots and tips begin to dry out. The onions can live off the bulb for approximately three weeks.

Do remove the plants from the box immediately. Keep them in a well-ventilated, cool area until you can plant them. Do not put them in soil or water.

Soil Preparation for your onions

Best Onion Varieties for Your Area

Onions require full sun and good soil drainage. Choose a location that gets plenty of direct sun. Onions grow best on raised beds or raised rows at least 4″ high and 20″ wide. The soil should be loose and crumbly. If it’s compacted, work in compost to improve aeration and drainage.

To stop weeds for up to six weeks, rake a pre-emergent herbicide, such as Treflan corn gluten meal, into the top inch of soil before you plant. Don’t worry, the herbicide will not affect the onion plant roots.

Soil Type for onion transplants

It’s helpful to know whether your soil is acid (pH below 7.0) or alkaline (pH above 7.0). Onions prefer soil with a pH between 6.2 and 6.8. Your agricultural extension service can test your soil for you, or you can buy a home test kit at your local garden center. Visit your local extension service for more assistance with determining your soil pH. If your soil is too acidic, mix in ground limestone, available at your garden center. If it’s too alkaline, add peat moss.

onion planting soil diagram


onion harvesting

Plant your onions transplants 4 to 6 weeks before the last estimated spring freeze. (Your agricultural extension service can tell you when that is.) For the best growth and yield, onions need fertilizer right from the start. Use a fertilizer with the middle number higher than the other two, such as our 10-20-10 Onion Special.

  • Dig a trench that’s 4″ deep and 4″ wide. Sprinkle ½ cup fertilizer per 10 linear feet of row. Cover the fertilizer with 2″ of soil. 
  • Plant the onions 6″ from the edge of the trench on both sides of the trench. DO NOT plant the onions in the trench! Leave a 2″ margin between the onions and the outside edge of the bed. 
  • Plant the onions 1″ deep and no deeper, as this will inhibit their ability to bulb.
  • If you want the onions to grow to maturity, space them 4″ apart. If you prefer to harvest some earlier as green onions, space them 2″ apart and pull every other onion during the growing season, leaving the rest to grow to maturity.

When planting onion transplants into several rows of onions, leave 16″ between the outside edge of one bed, and the outside edge of the next. The spacing from the center of one fertilizer trench to the center of the next should be 36″.

You can follow our Onion planting guide for more information; all orders include a planting guide, as well. You can also watch our YouTube video below on How to Plant Onion Transplants below!

To see our selection of onion plants available or place your orders, visit our  Web site. You may also contact Customer Service at (830) 876-2430 or email We look forward to another of providing the highest quality onion plants for you.