Heat-tolerant vegetable crops and cultivars for the changing climate

Our food-growing spaces allow us to grow healthy produce, connect with Nature, and hopefully save money. They are also a solid response to climate change and COVID.

My blog articles this year will be about climate-resilient food gardening. Each month I’ll address one or more aspects of how climate change is affecting our food gardens and changes we can make to reduce global warming and ensure a future of healthy harvests.

HGIC has a new Climate-Resilient Gardening section (thanks to Christa Carignan!) where you’ll find more information on these topics. We plan to continually update content and add new pages. And please check out the University of Maryland Extension’s new Healthy Garden, Healthy You project that connects food gardening and human health.

This first installment includes an overview of how our mid-Atlantic climate is changing and a look at heat-tolerant crops and cultivars. Future articles will explore low-dig soil prep, composting food scraps, peat alternatives, heat stress in plants, reducing plastics, and “hardening” our garden spaces.

Resiliency is mentioned a lot with respect to climate change. A climate-resilient garden can both withstand and recover from warmer, more extreme weather. Resiliency can also mean transforming how we grow food by creating and sharing a community knowledgebase of new ideas and techniques.

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Seed starting and soil testing: a Master Gardener outlines his spring gardening progress

In mid-February, I started my Gypsy, Monty, and Green Magic broccoli, Snow Crown cauliflower, Lacinato kale, several types of lettuce, and some Big Blue salvia.

Italian flat-leaf parsley was started in mid-January. Most of these transplants will be planted in the garden or containers in the first week of April after hardening off for at least a week in my cold frame. My pre-sprouted snap peas will be planted in late March. Planting dates for central Maryland can be found here on the Home and Garden Information Center website.

Kent's seedlings

In early March, I will be making a trip into Baltimore to get some other seeds for Sugar Ann snap peas, Jade string beans, and a couple of other things. In late March, I will be planting some seed potatoes in containers, just to see what the yield is. On March 27th, seven to eight weeks before the spring plant out date of mid-May, I will be planting Galine eggplant and several different types of peppers.

In previous years, I’ve planted tomatoes six weeks prior to my plant out date, but they have been leggy. This year, I’m planting them on April 10 for planting in the garden and containers on May 15.

My latest soil test, done in May of 2019, says to incorporate one pound of nitrogen (N) per 1,000 square feet. Only N is required since the beds contain the optimum amount of phosphorus (P) and potassium (K) and are at the correct pH.

To determine what fertilizer needs to be added to my beds which are 32 or 40 square feet, I will have to convert this recommendation to determine the amount of urea (46-0-0) to apply to my beds. This is fairly simple to do, using the following equation. Amount of N/.46 (% of N in urea) x beds size/1000 square feet. This yields the following: 2.17 pounds of urea x 0.032 for a 32 square foot bed equals .069 pounds of urea or 1.1 ounces. I guess I’ll have to get out my kitchen scale.

Alternatively, the University of Delaware suggested 2.5 pounds per 1000 square feet or 2.5 x .032 = 1.28 ounces of urea. This calculation works for almost all recommendations from soil test labs. However, if in doubt, you can always Ask a Gardening Expert at HGIC.

By Kent Phillips, University of Maryland Extension, Howard County Master Gardener

What can you start from seed in February?

I hope all of you are busy planning your vegetable gardens and getting those seeds ordered! If you haven’t purchased seeds yet, now is the time. A lot of seed companies are experiencing larger than usual interest and several have had to temporarily stop accepting orders. Many varieties of seeds are running out. So jump on it!

If you already have your seeds and your plan of action, you may be champing at the bit to get started. Those of us who start seeds indoors feel the urge to play in the dirt (or the soilless seed-starting mix) even in winter, but it’s often not a good idea. When I began gardening, I started many plants far too early, and was sorry later when I had enormous seedlings that couldn’t be put in the ground until the weather cooperated. So as a former offender, I will state clearly: DO NOT START YOUR TOMATO PLANTS IN FEBRUARY. In fact, do not start your tomato plants until late March or early April, and you will be much happier, and so will your plants.

But what CAN I start, you ask, with a pitiful, yearning look in your eyes. I know. I really do. Here’s a  list. It may not include anything you’re actually planning to grow, but I’ll give you another suggestion at the end. Here we go.

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Planting Vegetables in May

Maybe April is the cruelest month (especially this year) but early May can be tough on vegetable gardeners who are raring to go. You’ve got your spring crops in the ground and growing; maybe if you got an early start you’re even harvesting. But what about all those delicious summer veggies? If you’re lucky, you have some tomato plants, maybe some peppers or eggplant; you’ve got bean seeds and squash seeds and more. And you have well-prepared soil to plant them in. But when is it safe?

When can I plant these tomato and tomatillo TREES that I started at least a week too early?

When people ask me this, which they do a lot around this time of year, I usually sound a note of caution. But really, there’s no one clear answer. It depends on factors we have no control over, and it depends on how risk-averse you are. Many of us prefer to put a planting date on the calendar; even better if it’s an easy one to remember. St. Patrick’s Day: plant your peas and potatoes. Mother’s Day: time for the tomatoes to go in. But it’s not that simple. Continue reading

Seeds and Seed Catalog Jargon

Seed catalogs arrive this time of year with appealing photos of vegetable crops that buoy our hopes for a bountiful garden. The sheer number of vegetable, flower, and herb offerings is breathtaking, with seed companies offering 20 to 40 new cultivars each year. These may be brand-new releases or just new for a particular company. I recently scanned a few catalogs and discovered ‘Home Run’ melon, ‘Naval’ carrot, ‘Double Take’ columbine, ‘Rouxai’ leaf lettuce, and ‘Green Machine’ zucchini.

Seed catalogs

Companies often tout All-American Selection (AAS) Winners, cultivars evaluated and selected by a well-known independent, non-profit organization. Some of the small seed companies carry seeds from the

Open Source Seed Initiative (OSSI), a group of breeders and seed companies committed to open-source breeding.

There are dozens of wonderful seed companies and organizations that are a click away. But please also consider supporting local businesses and farmer co-ops with your seed and transplant purchases.

Seed Swaps

Seed swaps offer another great way to get and share seeds. These events are fun, educational, and interactive. National Seed Swap Day is January 25, 2020:  http://seedswapday.blogspot.com/ (information not yet updated for 2020).

Seed and Cultivar Terms Frequently Encountered in Seed Catalogs

Cultivar– a cultivated variety of a specific crop. Example: ‘Red Ace’ is a beet cultivar. Cultivar is a contraction of “cultivated” and “variety” and is often used synonymously with “variety.”

Open-Pollinated– an in-bred variety where individual plants in a population cross-pollinate each other and poduce nearly identical offspring. When grown using appropriate precautions, these varieties “come true” when seed is saved year-to-year.

Hybrid- controlled cross-breeding of two distinct, inbred, open-pollinated cultivars. The seed harvested from the intentional cross will produce an F1 (first filial) hybrid. Hybrids tend to be vigorous, uniform, and productive, and many have some disease resistance. Producing hybrid seed is labor-intensive, accounting in part for the often higher price. Hybrid seed is not true to type: seed saved from this year’s crop and planted next year will not be uniform in appearance or identical to the mother plants. Therefore, hybrid seed must be purchased each year.

Heirloom– open-pollinated cultivars that persist because their seed is saved and passed down from one generation to the next. They contain valuable germplasm that would be lost without the efforts of individual gardeners, farmers, small seed companies, seed-saving groups, and the USDA. They often have a colorful history and add interest to the garden and dinner table. Heirloom cultivars vary widely in productivity and disease and insect resistance.

Treated Seed– may be coated with a chemical fungicide (usually pink or purple in color) to prevent injury from soil-dwelling diseases after seeds are planted. The most common crops treated are corn, pea, and bean. Another treatment is immersing seeds in hot water to kill pathogens on, and inside of, seeds.

Untreated Seed- seeds that are not chemically treated.

Organic Seed- harvested from crops that are grown and certified according to the USDA National Organic Program (NOP) guidelines. To be certified “organic” seed must be produced and handled by certified organic producers. The NOP requires organic farmers to plant organic seed unless it is not commercially available. You can grow vegetables organically at home using non-organic, untreated seeds. Related resource: Organic Seed Alliance (national education, research and advocacy organization.)

Disease Resistant – ability to resist or impede a disease-causing pathogen. The level of resistance may be high or intermediate. This can also apply to insect injury. For example, sweet corn cultivars with long, tight ear leaves resist corn earworm feeding. Cornell University has excellent charts for identifying and selecting disease-resistant cultivars.

Disease Tolerant– ability of a cultivar to tolerate a disease infection or adverse environmental condition (e.g., drought, cold temperature) without a significant reduction in growth or yield.

Indeterminate / Determinate– the shoots of indeterminate tomato cultivars continue to grow and branch throughout the growing season. The shoots of determinate type cultivars reach a certain length and terminate in a flower cluster. Determinate tomato cultivars range in height from less than 1 ft. to 5 ft. and are sometimes referred to as “self-topping.”

Days to Maturity (Days to Harvest)- the approximate number of days to harvest, either from planting seeds or transplants. For tomato, pepper, eggplant, muskmelon, watermelon, broccoli, cabbage, cauliflower, and Brussels sprouts it’s usually days from transplanting, and for all other annual crops it’s days from direct seeding.

Parthenocarpic- flowers are able to set fruit without pollination and fertilization (of ovule by sperm cell). ‘Tasty Jade’ and ‘Diva’ are cucumber examples. ‘Cavili’, ‘Partenon,’ ‘Dunja,’ and ‘Golden Glory’ are summer squash examples. Growing a seeded cultivar nearby will lead to seeds forming in the parthenocarpic cultivar.

I learned that one of my favorite zucchini cultivars, ‘Costata Romanesco’ is largely parthenocarpic. A Cornell University study reported that 58% of bagged female flowers set marketable fruits.

Gynoecious- flowers are predominately female, leading to more fruits per plant. Unlike parthenocarpic cultivars, gynecious cultivars require pollination. Some companies include a second cultivar to plant that has both male and female flowers (monecious). Otherwise, you’ll need to buy and plant a second variety. Expensive cultivars (e.g. ‘Socrates,’’Tyria’) are available that are both gynecious and parthenocarpic. Seeds cost more because of specialized breeding and increased yield potential.

Pelleted– small seeds (carrot, lettuce, onion) are surrounded by a clay pellet to make handling and planting easier.

Primed– pelleted seeds may also be “primed” to reduce germination time. Seeds receive enough water to almost germinate, and are then dried and stored. These primed seeds break dormancy and germinate quickly when planted. The process also shortens the seed’s storage life.

Bolting (going to seed)- flowering prematurely, usually due to unsuitable climatic conditions at certain stages of growth. Spinach, lettuce, cilantro, broccoli, and endive are crop species prone to bolting.

Do you have a few favorite cultivars you’d like to share with us?

We would love to know which vegetable cultivars you would recommend to your fellow gardeners. Please send a list of your favorite cultivars to jont@umd.edu with a few words or a few sentences about why you like them (e.g., high yields, dependable, early maturing, heat tolerant, disease resistant, etc.)

By Jon Traunfeld, Extension Specialist

How to Choose a Seed Catalog

Like holiday decorations, seed catalogs seem to arrive earlier every year. They bring a bit of color and freshness into a cold and often dreary season, and winter gives us the perfect chance to sit down and plan next year’s garden. It’s SEED TIME!

seed catalogs
Seed catalogs. Photo: Erica Smith

But NO, I hear you say. I’m not ready yet! Well… maybe we don’t need to get organized about ordering seeds until sometime in the new year. As the catalogs slide into your mailbox, though, it’s a good time to review them and make some preliminary decisions about where you’ll get those seeds from. Even those of us who’ve been gardening for a while like to switch it up between vendors sometimes, and I’m sure many Maryland Grows readers who are newer gardeners have reached the point where they’re getting seed catalogs they never asked for, but which look tantalizing. But no one wants to pay shipping costs on orders of one or two seed packets from each company. How do you narrow the choice down? Read on for some criteria to make the selection easier. Continue reading