WESTERN (TX, AZ, NV, CA, NM, OK)

The Heat Breaks and the Real Season Starts

Field Note

August 28, 2026 — Overnight low of 63°F Saturday, then a full reversal: highs of 88–92°F with lows in the low 70s through September 3, rainfall chances under 15% until Thursday. This is the last block of usable heat units before the September decline, and daylength is already down about 75 minutes from the June peak. Florence, KY (Zone 6b).

I am closing my season. In the low desert you are starting the good part of yours.

Phoenix, Tucson, Las Vegas and the inland California valleys spend June through August in conditions that shut Adenium down. Above about 110°F these plants stop growing and go into heat stall — they are not thriving in that, they are enduring it. When September breaks the back of the heat, growth resumes, and October and November are the strongest Adenium months the low desert gets.

Texas splits the difference and Oklahoma and northern New Mexico look more like my situation. So the West needs to be read by sub-region more than any other territory.

Low Desert: Phoenix, Tucson, Las Vegas, Palm Springs

Feed and grow through fall. Your plants are coming out of stall, not going into dormancy. Keep feeding through October. Shift the ratio toward potassium as you go, but do not cut off early — you would be cutting off right as the plant starts working again.

Repot now. Soil stays warm into November. Your repot window is the widest in the country. Repot dry, hold water five to seven days.

When to stop fertilizing Adenium: stop all nitrogen-bearing fertilizer roughly six weeks before your average first frost, or when nighttime lows fall consistently below 60°F — whichever comes first. In Phoenix and Tucson that is typically late November into December. Some winters neither condition arrives, in which case reduce rather than stop.

Watch winter nights, not winter days. Low desert winter days are fine. The nights are the problem — clear desert skies radiate heat fast, and a 75°F afternoon can drop to 38°F by 5 a.m. Adenium take damage well above freezing. My trigger is the first forecast below 45°F.

Texas: Dallas, Houston, San Antonio

Three different climates under one state.

Houston (9a): functionally Gulf Coast. Long season, real fall growth window, high humidity, and rainfall management is your main media concern. Last nitrogen mid-November. Repot through October.

San Antonio (8b/9a): long season with occasional hard freezes. Fall is a strong growing period. Last nitrogen early November. Have a cold plan — the freezes that reach San Antonio arrive quickly and go lower than people expect.

Dallas (8a): a genuine four-season climate. First frost typically mid-November, so your last nitrogen is around the first of October and your repot window closes early to mid-October. Read the Cold Climate timeline shifted about four weeks later than mine.

Interior and High Desert: Albuquerque, Santa Fe, Oklahoma City, Reno

Your season closes early. Elevation and continental exposure mean first frost arrives in October, sometimes late September at higher elevations. Treat my Zone 6b timeline as roughly your timeline — repot done by mid-September, nitrogen stopped now, plants moved in on the first forecast below 45°F.

The compensation is that your winter storage conditions are excellent. Low humidity and dry air are exactly what a dormant Adenium wants. Growers here consistently get better overwintering results than growers in far milder but wetter climates.

Coastal and Inland California

Coastal (Zone 10, San Diego through the Bay Area): mild and mostly frost-free, but your limitation is heat units, not cold. Coastal fog cuts accumulated warmth, and growth slows even without a temperature trigger. Site plants for maximum sun and reflected heat.

Central Valley (9a–9b): long season, real fall growth window, and occasional tule fog periods that create the same wet-and-underlit problem the Northwest deals with. Get plants under cover before fog season.

The Media Question in the West

Western growers have the opposite problem from Gulf growers. Your issue is not drainage, it is water retention and salts.

Low humidity and high evaporation mean a mix that drains too fast needs watering daily, and daily watering with hard western water builds salt in the media fast. Salt accumulation shows up as leaf tip burn and stalled growth, and growers usually blame something else. Two fixes: leach thoroughly every third or fourth watering so water runs freely from the drain hole, and refresh the surface layer every fall, since that is where salts concentrate as water evaporates.

That surface refresh is what Desert Oasis Fall Top Dress is for, and it does double duty in the West — it clears accumulated salts and resets the crown. Pair it with Desert Oasis Potting Media on anything getting a full repot. Desert Oasis media →

Sowing in the West

Low desert and south Texas growers can sow in September outdoors with no supplemental lighting and get excellent results — your fall is warm and bright enough to carry seedlings through establishment and into a mild winter.

Dallas, Albuquerque, Oklahoma City and Reno growers should treat fall sowing the way I do: it works, but only under lights from November through February. Without lights, wait for spring.

Either way the flat needs media that holds moisture without going anaerobic. Desert Oasis Germination Media handles that. Fresh seed from India releases next week, and a Thailand shipment lands mid-September including six Adenium arabicum Thai hybrids.

What Goes Wrong

Leaf tip burn and stalled growth. Salt accumulation. Leach and top dress.

Cutting water and feed in September. You would be shutting down right as the plant wakes up from heat stall.

Cold damage on a night that never hit freezing. Adenium are damaged above 32°F. Clear desert nights drop further and faster than the forecast high suggests.

A repot that never establishes. Almost always watered too soon after. Hold five to seven days.

What Changes Next Week

Starting Tuesday, September 1, this publication moves to a Tuesday and Thursday schedule. Tuesday establishes the biological moment; Thursday delivers the protocol. September 1 opens the Cold Season series with the four-cohort overwintering trial. September 3 covers repotting and top dress in full.

What We're Growing With

• Desert Oasis Fall Top Dress — surface refresh that clears accumulated salts. Full media line back in stock next week.
• Desert Oasis Potting Media — for fall repots, with the air space Adenium roots need.
• Desert Oasis Germination Media — for your fall sowing window.
• Adenium seed — fresh India shipment releasing next week; six A. arabicum Thai hybrids mid-September.
  

The full regional breakdown — with specific timing and application guidance for Cold Climate, Pacific Northwest, Gulf Coast, and Western growers — is at americanadenium.com.

Cheers,

Michael