Tips for sowing vegetable seeds

Now that spring is on its way, I can’t wait to get out in the vegetable garden and get things growing! If you are new to gardening and/or growing vegetables from seed, here are some basic seed sowing tips to help guide you.

For starters, select the crops you want to grow based on what you and your family love to eat! Next, time your plantings carefully by getting to know your crop’s optimal growing conditions. Vegetables can be divided into two basic groups: warm season crops and cool season crops. Knowing which crop belongs in which category will save you time, money, and frustration, and increase your overall success.

In general, cool season crops have varying degrees of frost hardiness (Frost can in fact enhance the flavor of some cool season crops like kale!) and thrive when air temperatures are 75°F or less. As a result, these seeds can be planted early in spring when soil temperatures are as low as 35° to 45°F. Here is a comprehensive list of cool season crops to choose from: arugula, beet, broccoli, bok choy, cabbage, cauliflower, carrot, Chinese cabbage, Chinese celery, cilantro, collard, dill, endive, fava bean, kale, kohlrabi, leek, lentil, lettuce, mâché (corn salad), miner’s lettuce (Claytonia), peas, potato, radicchio, radish, spinach, Swiss chard, turnip, and wheat.

Warm season crops, on the other hand, cannot tolerate frost and need soil temperatures 60°F or above to germinate. Generally, these crops should be planted late spring (end of May) or early summer (June) once the danger of frost is past. Their optimal growing temperatures are when daytime highs are above 75°F. In short-season climates like Flagstaff, success comes with these crops by starting seedlings indoors 6-8 weeks before the last frost date. Transplants can shorten the number of days to harvest before frost kills your plants in the fall. The following crops are considered warm-season crops: basil, beans (pole, bush, lima, tepary, yard long), corn, cucumber, eggplant, gourds, melon, okra, peppers, sorghum, summer and winter (acorn, butternut, pumpkin) squash, sunflower, tomatillo, tomato, and watermelon.

To check your soil temperature, I recommend all mountain gardeners purchase a soil thermometer online or from a local nursery. A soil thermometer takes the guesswork out of planting not only for the correct timing of your cool and warm season crops but also to assess the micro-climates of each of your garden beds.

Once you have selected your favorite crops and know the optional time to plant, follow these steps to plant your seeds:

• Layout your planting areas in rows, blocks, or a hexagonal planting scheme.
• Adjust your layout based on the spacing needs for each crop, their mature size, and harvest techniques. This information can be found on seed packets.
• Select individual seeds from the packet by looking for ones that are plump and full sized, not thin, holey, or shriveled.
• Make small holes or depressions in the soil at the correct seed depth for the crop. Again, this information can be found on the seed packet and is essential to guarantee success.
• Gently place the seed in the hole and lightly cover with soil as you go.
• After all seeds are planted, grade the soil to create a level surface so that water will soak in evenly.
• Hand water after planting with a gentle spray making sure not to wash away small seeds.
• Until the seeds sprout, check your plantings daily and water as needed in order to keep the soil moist like a wrung-out sponge. If germinating seedlings dry out for even a short period, they can perish.
• On average, seedlings should emerge in 7-14 days.

Happy seeding!

Nate O’Meara is the Executive Director of The Arboretum at Flagstaff.