Growing Potatoes and Onions

If you’re anything like us, then you’re eager to get a start on your vegetable garden now that milder springtime weather is setting in. Although it’s too early to plant hot summer crops like corn and tomatoes, you’ll be glad to know that there are two crops that you can begin planting now: potatoes and onions.


      The potato is a member of the Solanaceae family, also known as the nightshades. This means that potatoes are related to tomatoes, peppers, eggplant, petunias and tobacco. According to Wikipedia, the potato was first domesticated in the region of modern-day southern Peru and extreme northwestern Bolivia approximately 7,000 to 10,000 years ago. If you travel to South America today, you will encounter potatoes of many shapes and colors like you have never seen before.

In our area, potatoes can be planted as early as late March and as late as June. Plant early for summer eating and later for fall storage. Although you can plant them so early, potatoes may not germinate until the soil has warmed. Don’t worry if they take a while to sprout.

When deciding where to plant potatoes or any other root crops that you plan to store over the winter, consider choosing a spot that will not be near other vegetables that will need heavy watering in the fall. This will allow your root veggies to dry out and store properly. Potatoes grow best in light, sandy, and well-drained soil. If you plant them in heavy soil, or soil that stays wet, you will have bad results. Tuber growth may be stunted, deformed, or even rot. Potatoes want full sun in order to produce their largest yield.

To prepare your garden soil, add mulch for drainage and apply an organic vegetable fertilizer. Compost is great, but you might also want to use a packaged product throughout the season. Do not use fresh manure because this can introduce maggots to the soil and they will eat your potatoes. If the soil is compacted, you might want to gently loosen it up to 12 inches deep with a pitchfork or hand tiller. Heavy tilling can damage the mycorrhizal fungi that will help plants roots take up water and nutrients.

Once the area is ready, you are ready to prepare your seed potatoes for planting. You will want to cut large potatoes into pieces so that each one has 2-3 eyes, or sprouts. Let the pieces sit in a cool, dry area for 12-24 hours, or until the cuts scab over. This will help prevent them from rotting in the ground. Plant the potatoes 3 inches deep, 12 inches apart, in rows that are 2-3 feet apart. Cover the potato pieces with soil and give them a good, thorough watering.

Now that you have them in the ground, don’t water the potatoes again until the plants are at least 5 inches tall. Many potato farmers don’t water until the foliage starts to wilt. This means that you may not be watering again until mid-June or even July, depending on the weather. Once you do start watering, maintain a regular watering schedule throughout the rest of the growing season. Irregular watering causes the plants to start and stop growing, which can result in funny shaped and sized tubers. Periods of drought can cause the tubers to turn black on the inside. If this happens, it's a sign of physical stress and not disease. In addition to water, potatoes require a good bit of fertilizer which we recommend applying until mid-August.

Potatoes form tubers along the stems between the roots and leaves. A good way to increase yield is to cover the stems with soil as the plant grows. The larger the mound of soil you build around each plant, the more potatoes you will harvest. Be careful not to cover the entire plant, however. Leave a good bit of foliage exposed for photosynthesis.

How do you know when the potatoes are ready for harvest if you can’t see them? A good indication that your potatoes are ready is that tiny white-to-purple star-shaped blossoms have begun appearing on your plants. If it’s not too much trouble, it’s ideal to carefully harvest the larger potatoes and leave the smaller ones to continue growing. However, if you damage the root system, then growth of what remains will be stunted. You can also just dig them all up at once and have potatoes of different sizes. For winter storage, wait 2-3 weeks after the plants have died down before harvesting the potatoes. This will allow enough time for the skin to thicken. Don’t forget about them and let them freeze in the ground, however. They will not store well after that. Once you get them out of the ground, let them dry for a couple days out of direct sunlight. Finally, choose only firm, healthy looking potatoes to be stored in total darkness in a temperature ranging from 40-50 degrees F.


      Onions are members of the Allium family which also includes garlic, shallots, leeks, and chives. The ancient Egyptians revered the onion as a symbol of eternal life because of its structure of concentric circles. Onions were often depicted in tomb paintings and have been found carefully placed inside mummies. In fact, King Ramses the IV was laid to rest with onions in his eye sockets. (Learn more about the history of onions at

Onions are commonly grown from sets or starts. Sets are dried bulbs about the size of a marble and starts are bundled young plants with about 5-6 inches of green foliage growing from tiny bulbs. In talking to our customers, we’ve learned that people often have tried both and find that they prefer one over the other. Red, white, and yellow varieties are available. Usually yellow varieties store the best.

Whether you choose sets or starts, the process is the same. Onions can be planted as soon as the soil can be worked in early spring. Like the potatoes, choose a sunny location away from where you’ll be watering heavily at the end of the season if you plan on putting your onions up for the winter. Before planting, soak onion starts in a glass of water until the roots soften. Onion sets do not need any preparation. Plant onions so that the bulbs are 1 inch deep, 3 inches apart, in rows that are spaced 1 foot apart. Onion bulbs are ready for harvest when the tops have fallen over. Pull them up and leave them to dry on top of the soil for several days before bringing them inside. Store them in a cool, dry place. If left to overwinter, onions will produce a flower and seeds the following year.

You can also grow your onions as green or salad onions. In this case, plant your starts or sets 2-4 inches deep with the bulbs nearly touching. The deeper you plant them, the more of the white portion you’ll get. You can harvest them in about 4-6 weeks after planting once the greens are about 10 inches tall. Replant throughout the spring every 2 weeks in order to have a constant supply for salads and garnishing. Green onions will last longer if you store them in a glass of water in the refrigerator.

Here’s to braving the unpredictable spring weather and getting your hands dirty!