End of Summer Nursery Update

We’re finally nearing the end of the extreme heat, and hopefully can squeeze a few more storms out of the season. Raising my first batch of seedlings through 110°F weather—mostly in black pots with heavy sun exposure—has been quite a learning experience.

While winters here in the Valley rarely dip below freezing, I’m curious to see how young plants will handle cooler nights. In the meantime, we’ve got a few months of excellent growing weather ahead, and I fully intend to take advantage of it.

🌱 Newest Starts

This week I sowed a fresh batch of:

  • Datura wrightii (sacred datura)
  • Senna covesii (desert senna)
  • Asclepias angustifolia (collected in Prescott)

Of these, Senna has been the trickiest—prone to rot if the soil stays too moist. For this round, I’ve adjusted my mix to less than 10% organic matter and over 30% perlite/lava rock, with washed sand as the base. These seedlings seem to hate excess water, so I’m optimistic this leaner mix will keep them happier.

Earlier this week I also started:

  • Strombocarpa pubescens (screwbean mesquite)
  • Chilopsis linearis (desert willow)
  • Olneya tesota (ironwood)

Germination has been strong across the board, with Chilopsis—no surprise—leading the way.

Ironwood quick early growth, barely a week old

My Baja fairy-dusters from late July are thriving, while chuparosas are surviving but clearly stressed in the heat. A couple Senna seedlings from my last attempt are hanging on, but this new batch already looks more promising thanks to scarification and better soil prep.

I’ve also started cascalote trees, which are showing rapid early growth. And in the fridge, I have a few species from the oak–juniper scrub of central Arizona undergoing cold stratification—a story I’ll save for its own post, since that trip was a highlight of my summer.

Since September is Plant for Monarchs Month here in Phoenix, I’ll also mention that I’ve got a batch of desert milkweed (Asclepias subulata) in the works, with the first round expected to be ready for sale by spring.

Young desert milkweed

🌳 More Mature Specimens

Some of my oldest seedlings are nearly ready for permanent homes:

  • A Chilopsis linearis started in January (now outgrowing its 11” treepot)
  • A Justicia californica (chuparosa) filling out a 2-gallon pot
  • Several mesquites (Neltuma/Prosopis) and palo verdes (Parkinsonia)
  • Vachellia farnesiana (sweet acacia)
  • Caesalpinia pulcherrima (red bird-of-paradise)

Chilopsis above ground growth at 6 months
Chilopsis roots at 6 months

Excitingly, I also made my first official addition to my own garden: planting a Justicia californica in the backyard! This one germinated in February and was over six months old when it went in the ground. I’ve set up a temporary 30% shade screen for its west side, and it’s sharing a drip line with other established shrubs. So far, it’s handling the transition beautifully.

Chuparosa planted, with perspective
Chuparosa planted, close view of stem/mound

Another milestone: I planted a Vachellia farnesiana along an alley cutout near an irrigation valve. After a month in the ground with zero supplemental water, it’s thriving—a reminder of just how tough these trees are, even in Phoenix summers.

In the coming weeks, a few more of my spring-sown seedlings will be finding homes around the neighborhood. A handful are still available for giveaway to good homes—check in via Instagram or Facebook if you’re interested.

🔎 Looking Ahead

For the rest of September and into fall, my focus will be on:

  • Raising the youngest seedlings through the last stretch of heat
  • Preparing for fall guerrilla plantings and spring availability, including new species
  • Possibly testing out white Zipset plant bands in place of black treepots, for cooler roots and less heat stress

As always, thanks for following along—and for your support as I experiment, learn, and grow.

🌵
Ammar
Sonoran Starts Nursery