Tag Archives: seed starting

How to Grow Onions

Onions are often touted as one of the easiest crops for beginners, but many folks need help for good production. Bulb onions can be a bit finicky, and if you don’t provide the correct conditions, your onions won’t bulb up properly. This quick-growing guide will get you on track for a big onion harvest, even if you’re a complete beginner.

Step One: Choose the Right Onions for Your Area

If you’ve browsed the bulb onions we carry, you’ve probably noticed that there are long-day (LD) and short-day (SD) onions. This designation is critical as it refers to the hours of daylight necessary to trigger the onions to bulb up.

Long-day onions need 14 to 15 hours of daylight to bulb, while short-day onions need 10 to 12 hours of daylight. For the LD types that we carry, you can plant them from Virginia northward. SD types can be spring or fall-planted in Virginia and fall-planted in the South.

Step Two: Start Onions Early

Bulb onions are one of the earliest crops we start at Southern Exposure. We begin tucking seeds into cold frames between September and January. You can also sow them in a greenhouse or indoors any time from mid-September through mid-March.

Just remember, earlier is better! Earlier sowing means larger bulbs because plants will get larger before the heat and lengthening days signal them to bulb up. 

Onions should be sown about 1/4 inch deep in flats or trays. If you’re new to seed starting, check out this guest post, Starting Seedlings, by our friend Pam Dawling, author of Sustainable Market Farming.

Guest Blog Post: Starting Seedlings

Step Three: Select a Good Location & Improve Your Soil

Onions grow best in bulbs with full sun and light, well-drained soil with a pH between 6-7. Soil that is too acidic or alkaline will cause slow growth and late maturity.

Onions are heavy feeders that require fertile soil with plenty of organic matter. Onions need abundant potassium and phosphorous for good bulb formation and plenty of nitrogen during active leaf growth.

To improve your bed for transplanting, remove all weed growth, loosen the soil with a broad fork, garden fork, or tiller, and add a few inches of finished compost.

Step Four: Transplant Your Onions

Transplant your onions early. Onion seedlings are hardy to about 20 degrees F. Set them out in February or as soon as the soil can be worked in the spring.

Plant your onions 3 to 4 inches apart in rows 12 to 16 inches apart. Crowding can reduce production, particularly in poor soil. Refrain from pruning the tops, or your harvest will be significantly decreased.

Step Five: Mulch them Well

Mulch around your onions with a thick layer of straw, old leaves, grass clippings, or other organic material. Mulch will help suppress weeds and aid in maintaining moisture and nutrient levels.

Step Six: Keep Up with Weeding

Yes, this is every gardener’s least favorite chore and seems like a no-brainer, but it is critical with onions! Experiments have shown that weeds can cause a 4% reduction in onion production in one day or a 50% reduction in yield in 2 weeks.

Onions have shallow roots, so you may need to weed them by hand. Cultivation between rows should be shallow. 

Step Seven: Harvest & Cure Your Onions

Harvest your onions when most of the tops have fallen over.

Some folks like to break the tops of their onions by hand to accelerate harvest. However, we’ve found that this harms the storage ability of some varieties and helps the storage ability of other varieties.

It’s best to harvest onions after a few days without rain so the soil isn’t muddy and difficult to work with. Pull your onions, using a garden fork if necessary, and cure them for 2 to 3 weeks until the necks have thoroughly dried. 

Cure your onions somewhere with partial shade and good ventilation. After this period, you can clip the tops to within one inch of the bulb. 

Texas Early Grano OnionsStep Eight: Rotate Your Onions Next Season

As with all crops, onions are subject to specific pest and disease issues. To continue getting good production, it’s best to rotate your crops. We like to rotate onions on a three-year rotation and compost any onion residue to keep them pest and disease-free. 

If onions have given you trouble in the past, following this guide can help ensure good production. Start your onions early, provide plenty of space and nutrients, keep them weeded, and harvest them properly. Happy gardening!

Basics: How to Start Seeds Indoors

Starting seeds indoors during the cold and dark of winter might be one of the greatest joys for a gardener. It means that greener, sunnier times are coming. Starting seeds indoors isn’t difficult, but there are a few tricks of the trade. Here’s everything you need to know to start seeds indoors and care for your seedlings successfully. 

Gather Supplies & Calendar

To start seeds indoors, you need a few basic supplies. You’ll need a shelf or table, containers, seed starting mix, lights, and a waterer. It’s easiest to have a good setup before you begin. You’ll also need to know the appropriate times to start seeds in your area. It’s a good idea to have or make a calendar for this. 

Earlier in our basics series, we covered what you need to start seeds and when you should start seeds. Please refer to those posts for complete details. 

Follow Planting Recommendations

When starting the seeds you purchased, follow the package instructions or the growing guide. 

Look at planting depth. Some seeds need light to germinate, and you’ll need gently press them into the soil’s surface, while other seeds need to stay moist and dark, and you should plant them at 1/4 inch deep or more.

Try using the tip of a pencil to make holes in the seed starting mix for your seeds.

Consider additional requirements. Some varieties need a bit of extra attention before sowing. Watch for seeds that should be soaked overnight or stratified before planting. 

If you have seeds you got from a friend or seed swap without directions, do a little digging about what that variety needs to thrive. 

Keep Moist

Your containers should have drainage, and you should avoid over or under-watering. Seedlings should be kept moist but not soggy. If the roots sit in water, your plants will fail to thrive. 

A pump-up water mister or sprayer can make watering much more effortless. Using a fine spray can help dislodge tiny seeds and seedlings, and you can swap to a larger traditional watering can as plants grow larger.

The larger your seedlings get, the more water they’ll use, so be sure to take extra care to check them as they grow. Using warm lights or heat maps can also increase your need for watering. 

Adjust Lighting

You’ll also need to adjust your lighting as your seedlings grow. As discussed in our previous post about supplies, you’ll need to provide your seedlings with auxiliary lights hanging above them. 

Keep these lights 2 to 4 inches away from the tops of the seedlings. As your seedlings grow, you’ll want to raise them, so they don’t burn the tops of the plants. However, if you notice your seedlings getting tall and spindly, you should lower your lights.


Seed-starting mixes are great for starting seeds but only provide a few nutrients. If your seedlings grow in containers for an extended period, you’ll need to give them fertilizer. 

The easiest way to give seedlings a boost is to add liquid fertilizer to the water. Liquid kelp is an excellent organic option, and just a tablespoon or two added to a gallon of water goes a long way. Some folks also choose to water with compost tea. 

For liquid kelp or other purchased fertilizers, follow package instructions when available. You should cut the amount in half if the instructions are for mature plants. 

Pot Up as Needed

Your seedlings may outgrow your containers before you’re ready to transplant them. It’s a good idea to have a few larger containers on hand, about an inch or two wider than the existing containers. 

Potting up provides fresh soil and space. If left in small containers, seedlings can become root bound where the roots wrap around the inside of the pot, and can take longer to begin growing after you transplant them. 

You should repot most seedlings so that the stem is at the same level as in the initial pot. Tomatoes can be repotted deeper, with soil covering the stem up to just below their leaves, as they will grow new roots from the stem. 

It’s almost February! In the Southeast, we’re ready to start seeds indoors, and you probably are too. Follow these tips to start seeds indoors and care for them until spring for a bountiful garden in the coming season.

Basics: When to Start Seeds

A common question we get is, “I live [insert your state here}; when should I plant [insert variety here]?” As a small organization, we would need more time to answer all of these, and we’d like to enable folks to determine all their planting dates. Here’s what you need to do to determine when to start seeds, no matter where you live. 

Find Your Zone

Knowing your zone will help determine your first and last estimated frost dates and average winter lows. Armed with this information, you can make better choices about starting seeds and what varieties of annuals and perennials are best suited to your climate. 

Find your zone by using the USDA Plant Hardiness Zone Map.

Get Local Recommendations

If you can read this blog on a phone or computer, you can also access many personal planting charts available. Our gardener planner app provides planting dates based on your zip code. You can also find free planting dates by zip code on the Farmer’s Almanac website

If you like books, we also recommend grabbing a local gardening guide. These typically include much more than just planting dates and can provide other handy advice for dealing with your local climate, pest issues, and soil conditions. 

Most extension agencies also offer planting dates. In many cases you can get a planting calendar for your state, regions, or possibly even county from your local extension agency. They often have good advice for what varieties thrive in your area too. 

Pick Your Own offers a list of agencies if you need help finding yours. 

Brassica seedlingsStarting Indoors: The Basics

We recommend starting most of your seeds indoors 4 to 6 weeks before you expect to transplant them. This amount of time works well for tomatoes, sweet peppers, eggplants, collards, cabbages, broccoli, and other brassicas. Some crops like onions, hot peppers, celery, and celeriac are slower to get started, and you should start them indoors about 8-10 weeks before you want to transplant them.

Winter is tough on gardeners, and it can be tempting to begin sowing seeds indoors extra early. Unfortunately, giving the plants extra time indoors can be detrimental. If seedlings get too large, they can experience greater transplant shock and suffer damage.

Direct Sowing: The Basics

Direct sowing dates vary widely with crop type. Hardy, cool weather-loving crops like peas and spinach can be direct sown months before the heat-loving stars of summer like squash and watermelons. Some flowers are delicate and can only be direct sown after all chance of frost has passed, while some can be direct sown in the fall to overwinter and get an early spring start. 

Read about your chosen varieties and look at your area’s estimated last frost date. For future years, keeping a garden journal about what you planted, when, and how it faired can be helpful.

Knowing when to start seeds doesn’t need to be guesswork. You can use these resources to start seeds at appropriate times and grow a bountiful garden.