October: What to Do in the Desert Garden

October is the month gardeners have been waiting for! The weather is getting cooler, and it’s prime time for planting desert landscape plants. Here’s a look at what you can plant this month (and the few exceptions), tips for taking care of your new plants, how to adjust your watering schedule, and more.

Why is this man singing in a garden center? Because he’s overjoyed that it’s October and prime planting time is here! I feel like this in October, do you?

As the temperatures cool down, garden activity ramps up. It’s time to get new plants in the ground and spend more time enjoying your garden. October is considered the all-around best month for planting. Here’s why…

Cool air paired with warm soil provides the ideal conditions for plants to develop healthy root systems with less stress to your plants. Cooler temperatures, shorter days, and less intense sun mean less chance of transplant shock.

Here’s a look at what you can plant, fall planting tips, how to water new and existing plants, and more.

October Weather Outlook

You should notice a cooling trend, especially towards the end of the month. October’s average highs and lows in Tucson and Phoenix are about 10 degrees cooler than September’s. Additionally, the sun is less intense as the UV index continues to drop.

Here’s a look at October weather averages in both Tucson and Phoenix.

October Weather Averages (Tucson)

High temperature	86°F
Low temperature	59°F
Precipitation	.72″
Relative humidity	33%
UV Index	6.1
Wind	13 mph

October Weather Averages (Phoenix)

High temperature	90°F
Low temperature	65°F
Precipitation	.53″
Relative humidity	28%
UV Index	5.9
Wind	6 mph

If you live elsewhere, enter your city or town in the search bar at TimeandDate.com to find your monthly averages. You can find your average UV index at UVIndex.io.

What To Do in the Garden in October

If you’re like me, you’ve been planning changes to your garden all summer — plants you want to add, move, or replace. But before you invest in any large or expensive new plants, do your homework. Choosing the right plant for the spot you have in mind can save you time, money, and disappointment. Here are the top 9 factors to consider before making any major purchases.

Here’s a snapshot of the activities you can and/or should do this month and those you should skip.

✅	Plant most plants
✅	Sow wildflower seeds
✅	Switch to fall watering schedule
✅	Protect new plants
✅	Top dress with organic mulch
❌	Don’t prune most plants
❌	Don’t fertilize most plants

Read on for all the details and exceptions!

What to Plant in October

October may be the ideal month to plant, but that doesn’t mean you should get out your shovel on October 1st. In October of 2024, we had 13 days over 100. If you experience abnormal heat, wait until later in the month to plant.

Here’s a list of what you can plant this month:

• agaves & yuccas*
• cold weather herbs & vegetables
• flowering bulbs
• perennials
• shrubs
• trees
• vines

*Cactus can be planted now while the ground is still warm, but the ideal time is in the spring.

It’s also a good time to:

• Sow spring wildflower seeds
• Separate agave pups and replant
• Divide non-woody perennials
• Spruce up your containers with shoulder season annuals

Planting Winter Annuals

A visit to most nurseries this time of year will wow you with eye-popping spreads of colorful annuals including pansies, snapdragons, alyssum, lobelia, stock, and petunias.

According to Marylee Pangman, Tucson’s leading authority on potted plants and author of Getting Potted in the Desert, winter annuals should be planted once the nighttime lows are consistently in the mid-fifties, which may or may not occur this month. She’s found that waiting for cool nights will help ensure your annuals are robust and beautiful. There’s no harm in waiting until November if October has been warm.

Planting Exceptions

This is not the best time to plant cactus, palm trees, or any frost-sensitive plants.

Planting Guidelines

Since you may be doing a lot of planting this month, let’s take a look at some planting “best practices” so that your plants get off to the best possible start.

Digging a Hole

Digging a proper hole is the first step in plant care. Putting a plant in a half-baked hole will doom it from the start. The rule of thumb when planting any desert plant is to dig a hole three times as wide as the root ball but no deeper.

If the plant is root-bound, score the root ball to cut through any circular roots.

Amending the hole is not necessary or advised for most desert landscape plants, especially natives, unless you know you have poor drainage. Backfilling with only native soil will help your plant develop a stronger root system. If you’re planting non-natives that prefer more fertile soil (such as bottlebrush, heavenly bamboo, or natal plum) amend with soil mix or compost. To know for sure, check your plant’s soil preference in our Desert Plant Library.

Learn more about digging the perfect hole here:
How to Dig a Hole in the Desert

Provide New Plants with Shade

Depending on the plant and its sun exposure in your yard, you may want to provide it with temporary shade. It’s still intensely sunny out there and your new plant almost certainly came from a garden center where it was shaded in a greenhouse or by shade cloth.

You can provide temporary shade with shade cloth or a patio umbrella. For small plants, you can use shade cloth or strategically place a patio chair.

Watering New Plants

Water new perennials every two to three days for the first two weeks, then reduce watering to once a week.

The University of Arizona recommends watering newly planted shrubs, trees, and vines according to this schedule.

Weeks 1 & 2	Every 3 – 4 days
Weeks 3 & 4	Every 5 – 7 days
Weeks 5 & 6	Every 7 – 10 days
Weeks 7 & 8	Every 10 – 14 days

Your first impulse may be to water any new plant well immediately after planting, but the Arizona-Sonora Desert Museum advises not to water cactus, agaves, or other succulents for one month after planting in the fall.

How often to water after this depends on the plant. You can check the ongoing water requirements for a particular plant in the Desert Plant Library.

Switch to Fall Watering Schedule

It’s time to start cutting back on watering frequency to help your plants prepare for winter. Too much water stimulates new growth, which is prone to cold damage.

However, if you’re experiencing unseasonably hot weather, wait until the temperatures have returned to normal before adjusting your watering schedule.

Continue to water deeply with each watering, using the frequencies in this chart as a guideline.

Not sure how to adjust your watering schedule for October?
Our Desert Watering Resources can help.

What to Fertilize

There’s no need to fertilize landscape plants in October, but what you can do this month instead is topdress your plants, especially new ones, with organic mulch or compost. Mulch retains moisture and protects plant roots from temperature extremes. As it breaks down, it adds organic matter to your soil and encourages the growth of beneficial microbes.

Also, you can continue to fertilize any container plants.

What to Prune

This is not the best time of year to do major pruning since it encourages new growth. But you can prune any dead, diseased, or broken branches on shrubs or trees.

Leggy or overgrown perennials can be cut back by one-third. That includes shrub-like perennials like brittlebush and globe mallow. You can continue to deadhead flowering annuals or perennials to encourage more blooms.

Garden Pests & Diseases

As the temperatures cool down, so does insect activity, so you should find you have fewer problems with insects this month.

You may notice caterpillar activity, but they are mostly done eating and are looking for places to pupate, so please leave them alone.

Today’s caterpillars become tomorrow’s butterflies.
🐛 🐛🐛 = 🦋🦋🦋

Continue to watch for cochineal on your prickly pear cactus. If you notice a cochineal scale infestation, hit it with a hard spray of water. That should be all you need to do to get it under control. However, if it’s persistent or particularly bad, cut off the most affected pads.

Upcoming Gardening Events in October

October is a big month for plant sales. There are so many, you may have to choose! The following organizations usually hold plant sales in southern Arizona this month:

• Boyce-Thompson Arboretum
• Desert Botanical Garden
• Desert Survivors
• Native Seeds/SEARCH
• Pima County Master Gardeners
• Tohono Chul

You’ll find a comprehensive list of nurseries, botanical gardens, and organizations that hold classes, events, and sales in our Tucson Gardening Event Guide.

Don’t live in Tucson? Look for online classes. You can participate in these no matter where you live.

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