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Cool Season Growing in the Low Desert

Article by Laura Neff, Education Assistant, published October 19, 2017.

We are lucky in the Southwest. Generally, we are lucky because of our beautiful ecosystem, but more specifically because we can grow year-round. There is always something that can be planted. The trick is knowing what to plant and when. What is usually a period when gardeners across much of the country are hanging up their tools, the fall and winter are seen as the easier times to grow in the low desert. Because of the mild climate during our cool season, there are few outside factors that can get in the way of a successful harvest. It is a time that a person can really BRAG about their garden. The trick is, knowing what to grow.

BRAG is in all caps because it is an acronym to remember what seeds can be started during the fall. If you live outside of the low desert regions of Tucson and Phoenix this guide also applies to you. You just may need to bump up your timeline from October planting to late summer. Consult your local planting calendar.

B: Brassicas

Broccoli, Cauliflower, Cabbage, brussels sprouts, bok choy, kohlrabi

It is recommended broccoli, brussels sprouts, cauliflower, and cabbage are started before the season begins as they are slower to mature than other cool season crops. Starting seeds early or purchasing starts gives you a jump start. The Native Seeds/SEARCH retail store in Tucson will be having their Annual Fall Plant Sale, October 20th - 22nd and brassica starts will be available. Ideal seed starting should happen in mid-September. If you missed the window on starting seeds, don’t fret. Just ensure you have your garden in a sunny location so that plants can come up to maturity before the warm spring temperatures hit.

Broccoli head. It is recommended that broccoli is started before the season starts due to it slow maturity.

R: Roots

Carrots, radishes, beets, parsnips, turnips

Recommended varieties: Dragon Carrots, French Breakfast Radishes, Golden Beets

Note on Radishes: If started when still warm, radishes tend to lean to a spicier flavor. For a milder flavor, plant later in the season, or a few rounds of radishes throughout the season for a variety of flavors. They mature quickly so succession planting is recommended.

Left: Carrots, Right: Radishes

A: Alliums

Onions and garlic

Recommended varieties: I'itoi's Onions.These onions love the Sonoran Desert fall and winter. If left in the ground during the summer, they will look dead. Don’t be fooled! Come the monsoon rains and the cool off, you will start to see small green chives pop out and continue to multiply throughout the low desert cool season.

G: Greens

Arugula, chard, collards, kale, lettuce, mustard, spinach

Recommended varieties: Magdalena Acelgas (Chard),Tarahumara Mostaza/Mocoasali (Mustard). These varieties have a long history of growing in the Southwestern US and Northern Mexico which means they tend to have a longer, more palatable season than those greens that are heirlooms associated with areas outside of the Southwestern US and Northern Mexico. If started when still warm, greens tend to lean to a more bitter/spicy flavor. For a milder flavor, plant later in the season, or a few rounds of greens throughout the season.

Note: Greens can be difficult in arid, hot climates. When under stress they want to produce the next generation and bolt. Growing in the cool season is useful but selecting varieties described as slow-bolting, heat tolerant, or grow well into the summer is a must.

Top Left: Lettuce, Top Right: Red Russian Kale, Bottom: Assorted Greens.

..about your PEAS

Recommended variety: O’odham Green Peas. These peas are a wonderful, native variety that tastes just as sweet right off the vine as they do dry and rehydrated in soups and stews!

Peas in their early stage.

Additionally, some favorites including fava beans, lentils, chickpeas, and wheat also thrive during the low desert fall and winter. These crops of Mediterranean origin prefers more temperate climates. Legumes like favas and peas are great nitrogen fixers and are used to aid in repairing and replenishing soil fertility that may have been drained during summer grow outs.

Most herbs including cilantro, oregano, thyme and, dill prefer the cool season as well. Cilantro, for example, prefers to germinate in soil less than 70 degrees F, so it is ideal to wait until the temperatures cool down. We recommend calypso cilantro as it is slow to bolt and can last into the spring months.

All of these crops are tolerant of light frost (see "greens" photo above). Unlike frost sensitive crops like chilies and tomatoes, they do NOT need to be covered and protected when light frost warnings occur. The cold temperatures have the potential to actually improve the flavor of many of these crops. If frost touches your cool season crops, avoid touching the leaves and breaking the cell walls. As the temperatures warm throughout the day, they will recover.

So, whether you are just getting started or are a cool season pro, now is the time to plant your cool season favorites!

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