When to Plant Onions in Tennessee?

In the heart of the American South, Tennessee’s rich soil and temperate climate create an ideal environment for gardening.

Whether you’re a seasoned gardener or a novice with a green thumb, understanding when to plant onions in Tennessee can make all the difference in your harvest. Springtime, around March 1 to April 15, would make for the ideal planting season.

Other than that, September and October are fine months for transplanting and overwintering onions, but they are less optimal than spring.

Join us as we explore the nuances of Tennessee’s unique climate and the best strategies to ensure your onion crop thrives in this picturesque southern state!

The Best Time to Plant Onions in Tennessee

When it comes to planting onions in Tennessee, timing is key. The Volunteer State climate and seasons offer a unique window of opportunity for successful onion cultivation.

In this case, we first have to take into account that onion crops are made for cool seasons. But this doesn’t mean that they are capable of surviving frosty weather.

The ideal timeframe for planting them is in spring, two to four weeks before the last frost date. Because frost dates differ depending on where you live, consider the hardiness zone you are in to target the best time to plant onions.

Planting Based on USDA Hardiness Zones and Frost Dates

Knowing which hardiness zone you reside in is a key factor in deciding when to sow onions.

An example would be if you’re living in zone 7, whose average last frost falls on April 3. Following the recommendation above, the dates for planting onions in zone 7 would be March 6 to 20.

However, if you’re living in zone 6 and zone 5, the sowing time would be March 24 to April 7 for zone 6 and April 2 to April 16 for zone 5, given an average last frost of April 30 and April 21 for each region, respectively.

With some basic calculation, you can make well-informed decisions about when to plant onions and their best plant-care routines.

Before growing onions in Tennessee, let’s get to know the average last frost dates of some of the state’s cities in the table below, as well as their planting time:

Planting in Fall to Overwinter Onions

An alternative time frame when planting your onions would be during fall. While you can start planting your white, yellow, and purple onion sets in August, the real gardening magic happens in September and October, when the weather takes a delightful dip.

So, whether you’re an eager autumn planter or a winter gardening warrior, there’s a perfect time to get your hands dirty! But protect the onion plants with straw mulch, row covers, or PVC tunnels to help them survive until spring.

Know Your Onion Varieties

A short-day onion thrives best in regions with 10 to 12 hours of daylight, making them particularly suitable for Southern areas of Tennessee like zones 7 and 8, as well as similarly warm regions in East Texas and Georgia. These onions are prized for their sweetness, making them perfect for immediate munch.

A long-day onion is the more light-demanding of the two types, needing about 14 to 16 hours of daylight. These onions are ideal for Northern areas (specifically, zone 5 in TN), where they receive longer daylight hours during the growing season.

However, intermediate-day onions would be the best option for most people in Tennessee, as they will develop bulbs in any zone.

10 Tennessee Onion Planting Tips

1. Invest in healthy and disease-free sets or transplants.
2. Plant in well-drained, moist, and fertile soil with a pH between 6.0 and 7.0.
3. Plant onion sets at least two to six inches apart.
4. Onion transplants should have a space of four to five inches in between them.
5. Both sets and transplants must be buried an inch or two deep.
6. Onions require at least an inch of water weekly.
7. Find fertilizers high in nitrogen for healthy foliage and bulb development.
8. To know when to harvest onions, check whether their tops have started to dry and fall over.
9. Cure newly harvested onions in a well-ventilated area until the tops are dry.

Conclusion

The timing of when to plant onions in Tennessee is a delicate dance with the seasons. March and April would herald the perfect time to sow your onion seeds or sets.

As winter bids adieu and the soil starts to warm, these spring months will give onions plenty of time to develop before temperatures reach 80 degrees or higher during summer.

Remember to give your bulbs full sun as well, unless you only plan to harvest scallions.