University and seed company experts answers real questions about vegetable variety selection

In a recent virtual panel from UNH Extension and UMaine Cooperative Extension, Heron Breen, Seeds Branch Area Coordinator in charge of Trials Programs for Fedco Seeds, and Lauren Giroux, Director of Product Selection and Trialing at Johnny’s Selected Seeds, along with Becky Sideman, UNH Extension Sustainable Horticulture State Specialist and Professor, and Mark Hutton, UMaine Extension State Vegetable Specialist, discussed exciting vegetable varieties for home gardeners, including new varieties for 2021.

We didn't get to all the questions viewers had for us, so we are sharing them here as a written Q&A. Enjoy!

What is the best way to get an accurate soil temperature reading, and what is the ideal temperature for planting a variety of vegetables?

Master Gardener Will Lowenthal writes that “Memorial Day, always the last Monday in May, is a traditional guide to the last frost date of the season in central New Hampshire. You can adjust this by a week or so depending on where you live, but remember the weather does not always respect the calendar! The temptation is always there to push the season, but doing so can result in a crop failure. Therefore, it is essential to have a guide to when crops can be planted (or transplanted). If you have a warmer microclimate, cold frames, or raised beds which warm up more quickly, you may try to start earlier. Measuring soil temperature is a good technique. Most cool-weather plants will not do well at soil temperatures below 40 degrees F. Oregon State University recommends taking the soil temperature at 9 AM for seven consecutive days, at a depth of two inches, and then averaging the results. A soil thermometer is essential for this.”

This vegetable planting guide from Colorado State University goes into detail on temperature requirements for specific vegetables. Generally speaking, cool season crops like leafy greens, peas, onions and root crops can germinate in soils as cool as 40 degrees, but most seeds tend to germinate best at between 70 and 80 degrees. Warm season crops are typically transplanted into the garden as seedlings, so the last frost date is typically what gardeners are focused on for those crops. For corn, beans, okra, and vegetables in the cucurbit family, soil temperature is an important consideration for direct sowing.

What does it mean when a variety description for corn references the number of rows?

The number of rows just means the number of kernels around the ear. Each row of kernels runs from the bottom to the top of the ear. An ear with more rows probably has a larger circumference, and is a bigger ear in general.  

A variety mentioned in this webinar doesn’t appear to be available on the seed manufacturer’s website. Why is that?

Most seed companies are seeing a high volume of orders, and some of those companies are temporarily restricting when gardeners can order seeds. In many cases, popular varieties may already be sold out for the season. Contact individual seed companies to learn more about availability of certain varieties, and with questions about ordering from their catalogs.

For growing radicchio, what can I do to minimize the deterioration of outer leaves as the heads mature? This has occurred with both round and elongated varieties in our organic garden.

Deterioration of outer leaves may be a sign of tipburn, which is a common physiological problem in many crops, including radicchio. In leafy greens, the outer edges of the leaves die because calcium is not able to move through the plant to reach those areas. This can be caused by uneven water availability, excess nitrogen, or extremely high humidity or high heat. To avoid that, pay particular attention to water management to try to avoid any water stress on the crop. Of course, it’s possible that the issue you’re describing is something else - if this doesn’t seem to fit your situation, utilize your state’s Extension service to either send photos or send a physical sample for diagnostics. In New Hampshire, you can email photos to the UNH Extension Infoline or submit a physical sample to the Plant Diagnostic Lab. In Maine, you can contact your local Extension office or submit a sample to their Plant Disease Diagnostic Lab.

What do you recommend for a pole bean variety?

Northeaster is a very reliable variety, suited for our region, as the name denotes. Seychelles is another nice option. It’s often a matter of preference between round-pods and flat-pods, and ambitious gardeners may also be interesting in growing beans that grow significantly longer like the red noodle variety.

This is a nice resource to learn about growing beans, from the University of Minnesota. 

What do you recommend for a butternut squash variety?

Honeynut produces individual, small, butternut squash that have good eating quality relatively quickly after harvest (most butternut benefit from some storage prior to eating). Metro is another option that produces a mid-size fruit, and it’s hard to argue with old-fashioned Waltham Butternut, the original and classic variety.

This is a helpful resource about growing winter squash and pumpkins from the University of Minnesota.

What varieties of brussels sprouts do you recommend? Do any have less aphid issues?

Divino and Speedia are nice options because their plant architecture may reduce cabbage aphid pressure. Becky Sideman from UNH compared Brussels sprout varieties in 2013-14 and published results here. Becky also specifically researched aphid issues in brussels sprouts. Becky’s favorite varieties are Diablo and Gustus, but she didn’t see any differences in susceptibility to cabbage aphid, unfortunately. Becky is looking forward to evaluating some of the newer varieties, including Divino.

This is a helpful resource from the University of Minnesota on growing brussels sprouts.

What cucumber varieties do you recommend? What about Sumter?

There are many types of cucumber, and many personal preferences. Heron likes Marketmore 76, a nice classic slicer. Becky likes pickling cukes, and prefers the parthenocarpic varieties, which don’t require pollination to set fruit - Excelsior is one of her favorites. Sumter is a traditional pickling variety with resistance to several diseases that should do well here.

This is a helpful resource on growing cucumbers in home gardens from the University of Minnesota.

What varieties of cauliflower do you recommend?

Heron recommends Bermeo, for its heat tolerance. If you’re not a fan of traditional white cauliflowers, consider some of the beautiful colored varieties now available: Flame Star (orange) and Graffiti (purple) bring some fun and different colors to the table.

Learn about growing cauliflower in home gardens in this resource from the University of Minnesota.

What varieties of basil do you recommend?

There are several new basil varieties, such as the Rutgers series and the Prospera series, that are resistant to downy mildew (a serious basil disease that arrives mid-summer and kills the plants in some years). The newer resistant varieties come in a variety of flavors, including ones that are closer to the traditional Genovese type. 

Learn about growing basil in home herb gardens in this resource from the University of Minnesota.

How about medium and regular shaped, tasty tomatoes?  Replacement for Pink Beauty?  Also, any better cultural techniques that give better results?

Lauren-Martha Washington or Abigail are two options. You may also look at German Johnson, Rose de Berne, and the Motaro series.

Cultural practices include utilizing mulch - either plastic or organic - but not putting on too early or the soil will stay cold.  Mulch helps manage splashing of soil onto the foliage, helping reduce disease issues. Utilize staking or trellising to support your tomatoes and elevate them off the ground. Soil testing is also a great idea for growing tomatoes, and UMaine and UNH both offer soil testing services.

Learn more about growing tomatoes in this resource from UNH Extension.

What recommendations do you have in the hot pepper family, that is not too hot?

Habanada is a habanero type with no heat! Beaver Dam, Red Ember and Krimzon Lee are other great options.

Learn more about growing hot peppers in this article from UNH Extension.

What about eggplant varieties?

Gaudi is a nice option, and is conveniently thornless. Traviota or Nadia are nice traditional Italian types, and for Asian eggplants, Orient Express and Ping Tung Long are good choices.

Learn about growing eggplants in the home garden in this resource from the University of Minnesota. 

What do you recommend for artichokes and fennel varieties?

All the local seed companies have varieties that are meant to be grown as annuals, which will work well for Northern New England.  The trickiest part of growing artichokes is that they need to be “vernalized” at the 4 leaf stage; in other words, they need to be tricked into thinking that they went through a winter. This can be accomplished by keeping the young plants at cool (35-50 F) temperatures for 8 to 10 days once they reach the 4-leaf stage. 

For fennel varieties, Orazio, Perfection and Finale are good choices. 

Do you have any spring wheat variety recommendations?

There is an excellent variety list published by the Northern Grain Growers group; it lists several spring wheat varieties that have been shown to do well in VT and Maine.

I always pick an “experimental” crop every year to try something new (I even grew cotton one year!).. Any suggestions of something to try - maybe a variety you don’t see commonly grown but you recommend?

Some fun but challenging experimental crops to consider are fennel, artichoke, sweetpotato, tango celery, sorghum and peanuts. 

Tomato variety recommendation for growing in a high tunnel?

It is possible to grow pretty much any type of tomato in a high tunnel - and they will do better in the tunnel than in a garden. The high tunnel environment will help reduce the normal field diseases that we see in garden tomatoes (septoria, early blight, etc.). However, because the high tunnel environment is conducive to other diseases, like leaf mold (Fulvia fulvum), many growers choose leaf-mold resistant varieties such as Geronimo, Rebelski, Bigdena, etc. These are often marketed as “high tunnel or greenhouse” tomatoes. 

What kind of tomato variety might be good for soil that previously had fusarium wilt? I hope I got rid of it, but I'm nervous because I lost most of plants last year! And do you have any advice on making sure the disease is gone?

It may be possible to have success by growing varieties that have resistance to Fusarium. Races 1, 2 and 3 exist - try to find varieties that have resistance to all three races, such as Mountain Merit and Mountain Magic. Unfortunately, if there are very high levels of Fusarium, the disease may overcome the resistance. It is best to rotate crops and to move the tomatoes to another location if at all possible - and to be careful to not move the fungus from the previous location to the new one on tools, etc. This is a case where it makes sense to combine multiple approaches: resistant varieties and crop rotation.

Any suggestions if you have to grow in pots for what to look out for in seed catalogs? I find ones that are labeled “great for containers” have mixed success for me.

Johnny’s has a symbol for varieties that have been evaluated  in containers. In general, look for terms like “bush”, “compact growth”. 

This fact sheet from UNH Extension addresses cultural considerations for succeeding with growing vegetables in containers.

Black peanuts - we grew a plant last year and would love some advice on doing it better and when to harvest?

In general, peanuts require as long a growing season as you can give them. They do quite well from transplants - I like to start peanuts in 36 to 50-cell trays, and aim to transplant out once the soil has warmed to at least 60F - this means no earlier than June 1 for much of NH and Maine. They benefit from rowcover for additional warmth, early in the season. They should be dug as late as possible; the plants themselves can take a light frost, but they should be dug before a hard freeze. In our shorter growing seasons, we don’t typically get as high yields as southern regions, but it can still be worthwhile!

What varieties of okra do you recommend?

There are several productive early varieties: Cajun Jewel, Jambalaya, Clemson Spineless.

There are also some very attractive novel varieties, like Jing Orange and Louisiana Long Pod that can do quite well in our climate.

Resource List

When to plant your vegetable garden

10 Easy Steps to Prevent Garden Diseases

Vegetable Varieties for Maine Gardens

Fedco Seed Catalog. Page 4 shows how to read variety descriptions

Johnny's Planting Tools and Calculators

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