Vegetable Gardening at High Altitudes

Here are a few pointers to being a veggie champion at 7,000 feet.

There are amazing benefits to living at high altitude in Northern Arizona – four seasons, great mountain scenery, extremely clean air – but truth be told, it can be a challenge for gardeners.

Challenging, but not impossible. All it requires is a little planning, a little patience, and a few modifications. But the rewards – beautiful, healthy, homegrown goodness – are worth it.

Here are a few pointers to being a veggie champion at 7,000 feet.

Understand Your Microclimate

Depending on your neighborhood, the greater Flagstaff area ranks anywhere from a “5” to a “6a” in the USDA hardiness zone, the map of average temperatures that gardeners use as a guide for the growing seasons.

A couple of miles can make a huge difference here. The base of Mount Elden, part of an “inversion zone” where the air temperatures above ground are warmer, is likely to get several more weeks of optimal growing time than a garden located in Fort Valley or Baderville.

So, it’s important to understand your microclimate and plan your garden accordingly. If you only have 80 frost-free days, you might want to avoid that squash that needs 100 days to mature. Warner’s Nursery has planting guides that can help you understand your area and which veggies will do best in your garden.

Amend Your Soil

The quality of your soil will play a big role in whether your vegetables get enough water to survive and nutrients to thrive. Again, depending on the area, Flagstaff can be challenging, with neighborhoods that have clay soil, cinders, giant boulders or soil that has just too much alkaline.

The key to treating your vegetables right is treating your soil right. Amendments will balance soil pH, increase water-holding capacity and make the dirt easier to work with. If you have a limited amount of space or extremely poor soil conditions, you might want to consider a raised-bed garden. A 12-inch deep bed provides plenty of room for most vegetable roots. (Quick note on this, however: you probably won’t want a raised bed on a wooden deck; the weight when full of dirt and water might cause structural damage.)

Find the Right Seeds and Plants

A good vegetable garden starts with high quality, recommended seeds and plants. Given our climate, try for seeds that only require a short growing season and are “cold hardy.” Our seed selection at Warner’s is specific to Flagstaff to help take the guesswork out of your gardening. If you are starting your garden with transplants, pick ones that are healthy and a bit stocky.

Location, location, location

This time, we are not talking about where you live, but the neighborhood in your garden that your veggies will call home this season. First of all, find a sunny locale; vegetables like about six hours of sunbathing each day. Space them out properly so they don’t have to compete for nutrients and water.

Plant Properly

Whether you are starting from seed or using transplants, there are a few guidelines that will promote veggie success.

For seeds, mark out straight rows for easier cultivation and follow the directions for seed spacing on the package. Make sure they are planted at the proper depth (for example, lettuce and carrots only need a half inch of soil coverage, while beans and peas require up to two inches).

Transplants need tenderness as they move from their pots or flats into your garden. Don’t let them dry out before you get them in the ground, and water thoroughly before taking them out of their containers. Be careful with the roots and disturb them as little as possible (although if the roots are all bundled up or “pot bound” you might want to tease them out a bit). Dig a hole large enough so the plant sits slightly deeper than it was in the container, and cover with soil, making sure there are no air pockets. You might want to use a starter solution, and we can help you with the best selection for your plants.

water well

Irrigate to keep your soil moist and be consistent about it. Excessive fluctuations in soil moisture can adversely affect the growth and quality of your vegetables. Frequency of watering will depend on several factors – is your vegetable shallow- or deep-rooted? Is it a large or small plant? And of course, what’s the weather been like – if we’re in monsoon season, the need to water is less urgent. And don’t forget the mulch, which will help prevent evaporation.

Prepare to protect your plants

If you are like me, you treat your plants like botanical children, doing everything you can to make sure they grow up right and protecting them from the world that can be harsh. And, hard as it is to believe, your sweet tomatoes, cute carrots and beaming Brussels sprouts have enemies – unpredictable frosts, bullying weeds, pests and diseases. Our experts at Warner’s can provide you with the advice and products like frost blankets, plant treatments or weed suppressants to shield your veggies.


All this work leads up to the biggest reward of your veggie garden: the harvest. In my humble opinion, no purchase from the produce section can match your homegrown vegetable garden – the taste, the smell, the knowledge that your veggies are free from harmful chemicals, and the satisfaction of a job well done.

Happy gardening! FBN

By Misti Warner-Andersen

Misti Warner-Andersen is the manager of Warner’s Nursery & Landscape Co., located at 1101 E. Butler Ave. in Flagstaff. To contact Warner’s Nursery, call 928-774-1983.

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