Spring Sprouts: Onion & Potato 101

 

    Onions and potatoes; some of the most durable and stable produce that you can grow at home. While these veggies are quite boring compared to your bright, red tomatoes or tall, silky corn, they deserve extra love due to their great storage habits, full range of use in the kitchen, and they are one of the first veggies that allow us to get our hands in the dirt after a long winter.  

How to begin? 

    In early spring at Sunshine Garden Center, you can find seed potatoes and onion sets available for purchase. 

• Seed potatoes are potatoes specifically sold for the purpose of planting and growing. 
• Onion sets are tiny, dormant onions that mature to full-sized bulbs in around 14 weeks. 

Our seed potatoes and onion sets are certified to be free of viruses and other diseases that could affect your soil, which is a main reason you shouldn’t attempt growing these veggies from the grocery store. Come into the store in mid-March to shop our varieties and ask any questions!

Timing

    A key factor of success for planting potatoes and onions is the soil temperature. The ideal time to plant your seed potatoes and onions around Diamond, IL is when the daytime temps are consistently reaching the mid 50’s, which is around early to mid-April. 

Garden bed preparation

    Both onions and potatoes like slightly acidic, well-draining soil that is free of any rocks or debris. Give a quick weeding before planting to keep weeds at bay, decreasing the competition with your small veggies and saving you from weeding tons down the road.

    Onions, more than potatoes, grow best with a little extra love and nutrition, so consider raking in some compost, aged manure pellets, or another organic compound to your bed often for the best results.

These veggies love their sun, so make sure your bed receives at least 6-8 hours of sun daily. 

Preparing to plant

Potatoes

    Before putting your seed potato in the dirt, there is some prep work to do. At minimum, your prep will take 1-2 days, but can take up to 2 months if you try chitting. Use the instructions below to prep your taters for the soil. 

1. Cut your large seed potatoes into 3-4 chunks, with 1-3 eyes per chunk. 
2. Spread out your potato chunks on a tray or paper towel 
3. Let them sit for 1-2 days to form a protective crust on the cut sides. This will prevent the potato from rotting in the soil.
4. You’re ready to plant!

Onions

    Onion prep is a breeze, as they are “set” and ready to plant! Perhaps the only thing to take into consideration is the set size. 

• Larger sets (larger than a dime in diameter) are best used for green onions. This is because if these larger sets are allowed to grow, they are more likely to bolt. Bolting means flowering prematurely; the plant then shifts its energy toward seed production rather than bulb growth. 
• Small sets (smaller than a dime in diameter) are best used as bulb onions since they are less likely to bolt, therefore growing large, dry onion bulbs. 

Planting

Potatoes

    There are dozens of different methods to get a bountiful potato harvest. The options differ in spacing, ease of harvest, and ease of planting. Listed below are three popular methods. 

In the ground

1. Grab your shovel and dig long trenches in your prepped bed that are 6”- 8” deep and 6” wide. Keep your trenches 2’ -3’ apart for adequate air circulation.
2. Begin placing your potato chunks in the trench with their eyes facing up. Spacing should be 12” -18” between each piece.
3. Gently fill in the trenches, covering your seed potato pieces and ensure they will not be exposed to direct sunlight. 
4. Give your newly planted potato pieces a thorough watering.

Pot/ Container

1. Choose a well-draining planting container that is rated to hold 15 gallons, such as a fiber grow bag.
2. Using a soilless potting mix intended for vegetables with some compost, place the potting medium in your container. You want 4-6 inches of soil at the bottom. 
3. Arrange your seed potato chunks on top of your soil, 6 inches apart from each other, and 4 inches away from the sides of the container. 
4. Cover with an additional 2 inches of soil. 
5. Give your newly planted potato pieces a thorough watering.

No-Dig Method

1. Drag a shovel across your planting area to create a shallow trench that's about an inch deep. If doing multiple trenches, keep the spacing 2-3 feet apart.
2. Place your seed potato chunks 12-18 inches apart, keeping the eyes facing up. 
3. Mound your pieces lightly with 2-4 inches of soil.
4. Give your newly planted potato pieces a thorough watering.

Onions

There are two commonly used methods for planting onions; in the ground and in containers.

In the ground

1. Into loose soil, you can gently press your small sets 1-2 inches into the soil up to the neck, with the pointed end sticking out of the soil. Beware, planting deeper than 2 inches can negatively affect bulb development.
1. For small sets, maintain 3-6 inches of spacing.
2. For large sets, plant them closely, about 1 inch apart. Because these sets are best used for green onions/ scallions, the spacing requirements are minimal. 
2. Give your newly planted onion sets a thorough watering.

Containers

1. Choose a well draining planting container that is rated to hold at least 5 gallons, which will support 4-6 onions. 
2. Using a well draining potting mix with some compost, begin filling your container until your container has at least 10 inches of soil at the bottom. 
3. You can gently press your small sets 1-2 inches into the soil up to the neck, with the pointed end sticking out of the soil. 
4. Give your newly planted onion sets a thorough watering.

Growing Season Care & Maintenance

Potatoes

    Potatoes require “hilling” throughout the summer to increase yield and prevent greening. 

    As your little potato plants grow to 6-8” tall, add 2”- 6” of additional soil, mulch, or grass clippings at the base of the plants, ensuring that any exposed potatoes are covered and the top leaves still poke out. Repeat this hilling process as the plants grow another 6-8 inches (2-3 times per growing season.)

Through the summer, water as the soil dries out or the leaves begin to wilt. Potatoes require 1-2 inches of water a week until the foliage begins to turn yellow and die off. 

Onions

    Onions are a bit more needy than potatoes in their maintenance. In addition to feeding the soil every few weeks, there are stages to look out for in your onion plants. Doing so will help increase utilization in your kitchen. 

Green Onions

• If you harvest green onions off your sets, or have planted your large sets for green onion/ scallion harvest, you’ll find they are typically ready 4 weeks after initially planting, and can be harvested as needed through the summer.
• Trim the dark greens for them to grow back through the season, or pull your green onion to use the whites in your cooking.

Bolting Onions

• Pull any onions that have sent up flower stalks. Once the plant begins flowering, it means the bulbs have stopped growing. It’s recommended to use these onions within a few days of pulling, as these onions do not store well.

Harvest and Curing

Potatoes

    Lucky for us, potatoes can be harvested early for smaller “new potatoes,” or later in the season for full-size storage potatoes. 

Early harvest aims at collecting small, tender potatoes with thin skins, while leaving the rest of the plant intact to continue growing through the season. These little taters are ready 2-3 weeks after the plants finish flowering. 

• To collect your early harvest, gently dig near your plants and remove a few potatoes that are around the size of a golf ball. 

    Maincrop harvest is when you will garner larger, mature potatoes that store best. As a general rule of thumb, wait to harvest until the vine dies back naturally. However, leaving the potatoes in the ground 2-3 weeks after vine death is preferable if you want thick-skinned storage potatoes. 

• If your taters were planted in the ground, gently dig around the plants with a shovel or garden fork, being cautious of the tubers. Once the soil is loose, you can gently lift the potatoes from the ground and separate by hand. 
• If you planted your potatoes in a container, tip out the contents of the container and collect your potatoes by hand. 
• Curing potatoes for storage toughens the potato skins and extends storage life to ensure you get the most out of your harvest. 
• If temps are less than 80°F, leave your harvested potatoes in the field for 2-3 dry days for them to dry out.
• If temps are higher than 80°F or wet, cure in a cool, covered area for a couple weeks (eg. cool garage, cellar, basement)

Onions

    Your onions have made it to mid-summer without bolting! Great work! As you are waiting for the final onions to ripen up, keep in mind that onions should be harvested prior to late-summer/ early fall, when conditions are rainy and wet. 

• When the onions begin to mature, the foliage will become yellow and begin to fall down. Once half of your onion stalks have fallen over, you can manually bend the rest over to speed up the final ripening process.
• At this point, you can also begin to loosen the soil around the bulbs to encourage drying. 
• When the tops are brown, or a couple days after bending the tops, you can begin harvesting the onions. Remember to handle them carefully, since the slightest bruise will encourage rot in storage. 
• Cut the roots off, and trim tops to 1-2 inches unless you plan on braiding them together. 
• Place the plants in a warm, dry place away from direct sunlight to cure. 
• After cured, you can braid the onions, or store appropriately. 

    From slicing and grilling, to boiling and mashing, onions and potatoes are some of the most versatile veggies to grow. Additionally, being generally easy to store, these reliable plants grant you the ability to enjoy your harvest months after first collecting. Just think of a savory home-made baked potato soup in the dregs of a snowy winter.. Sign me up!

Still have more unanswered questions? Stop by the store and ask for Courtney.