By Laura Kourajian, Certified NDSU Extension Master Gardener
This year we may feel increased concern regarding food insecurity due to the COVID-19 pandemic. This, along with the movement to learn where our food comes from and the desire to provide our own food, may lead more people to invest in growing their own vegetables and fruits.
In the following Q & A, NDSU Extension Master Gardener Laura will provide answers to some common questions and links to science-based publications that can help. If you can’t find your answer here, please contact your NDSU County Extension Agent. There is a handy North Dakota map with click-on bubbles for each county extension office, including all contact information, here: https://www.ag.ndsu.edu/extension/ county-extension-offices
Q: My grandmother always did (fill in the blank) when she planted her garden, so I’m planning to do that, too.
A: What our grandmothers did was sometimes tried-and-true and still works today, but much of what they did was limited to old wives tales, family lore and scientific knowledge available at that time. It’s always best to double-check against what current science-based research recommends. NDSU Extension has dozens of publications available to address many common gardening questions with science-based answers, all categorized on the left side of the linked page. Some of these publications are also available in paper form at your local County Extension office.
Q: I’m going to dig up a section of my backyard or rent space in the community garden. I’m thinking “Go big or go home,” right? Is that a good idea?
A: While you may want to grow a lot of vegetables, it’s best to be modest in the first year. All those seeds and different varieties in the garden center displays look so tempting and the varieties of bedding plants in the greenhouses just beg to be added to your cart.
Putting in a large garden can be overwhelming come midsummer when the weeds are threatening to overtake everything, watering needs expand and the novice gardener can’t keep up. Ease your way in with a few well-tended plants in containers on the patio or choose just a few favorite veggies and put in a couple of 10-foot rows.
As a new gardener, you may wish to participate in the NDSU Home Garden Variety Trials and order seeds for two vegetables to try. Garden expansion can happen in future years, once you’ve has gained some skills. In the meantime, you can augment your garden harvest by buying local produce from a farmer’s market or from the local grocer.
Q: Do I have to get new seeds every year?
A: Seeds are packed for use in each new year, and the year should be clearly labeled on the packet (Fig. 1). There’s no problem in using seeds that are a year or two old, but the germination rate for those seeds will likely be affected so not all of the seeds may produce plants.
There are simple tests to check germination rate that can easily be accessed via the internet. Seeds that are more than two years past their prime planting date are likely not going to germinate well, but there’s no risk in testing them before tossing them.
Q: Should I buy seeds for everything I want to grow or should I buy plants that can be transplanted into my garden?
A: Many vegetable seeds can be directly sown into the soil in North Dakota, but others need to be started indoors by the gardener or purchased as transplants at the local garden center.
The average growing season is around 120 days (the length of time from last frost in the spring to first frost in the fall), but can be as short as 105 days or as long as almost 160 days, depending on the year, your location in the state and any microclimates for your garden.
Any vegetables that require more than 90-100 days from seed to harvest are best started indoors or purchased as transplants. This generally includes tomatoes and peppers as well as a few others. Most other vegetables can be directly sown as seed, but read the packet to see what it lists as number of days to harvest.
Keep in mind that unless the gardener is harvesting for purposes of preserving food for the winter, he or she may want the vegetables to be ready for harvest before the first day of frost in the fall. Staggering planting of seeds over the course of a couple of weeks means vegetables will be ready over the course of a couple of weeks at harvest, rather than all at once.
Q: I picked up a 6-pack of tomato seedlings at the plant store. Should I plant them right away?
A: Transplants are tender, having been spoiled by being raised in the perfect conditions of a greenhouse. Gardeners should pick out the best, strongest looking transplants, but even then it would be quite a shock to drop them into a hole in the ground in the North Dakota outdoors without letting them get used to it first by hardening them off.
Put them outside for a few hours a day, lengthening that amount of time until they are out overnight for a couple of days before putting them in the ground. The gardener may want to wait to plant until night temperatures are at least 50 deg F (usually around end of May but may occur earlier). All transplants require hardening off, whether vegetable or floral.
Q: Fertilizer? Help!
A: The best practice, whether you’re starting a new garden or planting in an established bed, is to have your soil tested to determine the levels of nitrogen, phosphorus and potassium as well as micronutrients in your soil. The NDSU Soil Testing Lab can take care of that for less than $20, and complete instructions are available online!
In addition to eight or more hours a day of sunshine, vegetables require nitrogen to flourish. Some vegetables require more than others. NDSU Extension typically recommends a commonly available fertilizer with a formulation of 15-23-10 (percentages of nitrogen, phosphorus and potassium respectively) spread at the rate of 3 to 4 pounds for each 1000 square feet of planted area. Mix in the fertilizer at the same time you are tilling in the organic matter.
However, if the soil test indicates a surplus of phosphorus, a different fertilizer that lacks phosphorus will be recommended. A surplus of phosphorus can result in stunting and poor growth in general.
If the gardener is growing vegetables in a container and using potting soil that already includes fertilizer, there is no need to add fertilizer at the start. Once the plants begin to flower, use a water soluble fertilizer at ½ concentration weekly. The same formulation can be used for leafy vegetables.
Manure, which has been used as organic matter in gardens for years, is now under review as it has been identified in crop fields around the country as a source for E.coli and salmonella contamination in food.
South Dakota State University Extension has a guide on growing vegetables that covers fertilization as well as other vegetable gardening information.
Q: What about bugs and other pests in my garden?
A: The use of pesticides, whether chemical or organic, is a complicated topic. Pollinators, like bees and other “good” insects, are just as harmed by pesticides as the insects and pests that are eating your tomatoes.
NDSU has a publication on using pesticides that can answer most of your questions and supplies solid information.
Q: What is the best way to water my garden?
A: While watering a garden doesn’t seem like rocket science, there are practices that will improve gardening success. Deep, weekly watering instead of daily, shallow watering is best. Sometimes Mother Nature takes care of that. Sometimes you have to help her out a bit.
It is best to water growing plants from below rather than from above. Of course, nature waters from above in the form of rain, and we love it when it rains in North Dakota unless it rains too much or at the wrong time. Nonetheless, we can’t do much to change the course of rain.
If the gardener has to supplement Mother Nature, laying a soaker hose (one that slowly drips water from small holes along the length of the hose) in the garden is the best way to water. It allows watering right at the base of the plants, ensuring it is getting to the roots. It also prevents water from splashing dirt and microorganisms onto the plants.
The most important thing about watering is to ensure the vegetables are getting watered regularly and evenly. Vegetables that aren’t kept evenly watered are going to suffer – tomatoes may develop blossom end rot, potatoes may have hollow centers, and more.
Vegetables growing in containers will need watering more than once a week, and during the heat of the summer will likely need watering daily (and possibly more than once a day) unless Mother Nature is helping out. Again, regular and even watering is crucial to prevent problems with vegetables.
Q: Why isn’t the sweet corn I planted germinating well?
A: Sweet corn needs soil temps between 55 degrees and 65 degrees to germinate, and certain types need warmer temps while others will do well in the cooler temps. If the gardener planted seed that prefers warm temps when the soil was too cold, it may not germinate until the soil warms or may not germinate at all.
Synergistic, hybrid Se/se and hybrid sh2 super sweet do not germinate in cold, wet soil. For best germination of these varieties soil temperature should be in the 70 degree F range; use a soil thermometer if uncertain.
The University of Minnesota Extension has an excellent web page devoted to sweet corn with information for home gardeners on choosing the right seed, what soil temperature is required for germination and how to care for the crop.
Q: Why are my tomatoes turning black on the bottom as they ripen?
A: That is called blossom end rot and is most likely caused by uneven watering once the plant has set fruit. Tomatoes need calcium, and there is often enough calcium in the soil but if it the soil dries out when the fruit is developing, the roots can’t move calcium into the plant and blossom end rot is the likely result.
As long as we’re on the subject of tomatoes, tomatoes can be pruned early to develop strong healthy plants that will produce healthy fruits. Gardeners should remove flowers until plants are 12-18 inches tall, remove suckers (small branches that are just getting started) beneath fruit clusters, and pinch the tip off about a month before the first frost is expected.
Q: What vegetables should I plant first?
A: Cold season crops are seeds and plants that can withstand the cooler temperatures of spring can be planted early. They include peas, lettuce, radishes, carrots, beets, spinach, kale and collards. These seeds will germinate in cold soil. In fact, the leafy greens will bolt, or quit producing leaves and start producing flowers and seeds, when the temperatures get warm.
Potatoes, which should only be grown from certified seed potatoes, can also be planted in cold soil.
All other seeds should be planted when the soil temperatures get to 50 degrees or warmer as it takes warmer temperatures for their seeds to germinate.