Pachypodium from Seed: Pacific Northwest Guide

PACIFIC NORTHWEST — Zones 7b–9 (OR, WA, Coastal BC)

Pachypodium from seed is entirely achievable in the Pacific Northwest, but the challenge here isn't cold — it's heat. These plants need sustained warmth to germinate and to grow at a pace that produces meaningful caudex development in a season. In the PNW, June gives you your best window, but the setup matters more than the calendar.

FIELD NOTE — June 18, 2026 — Sunny, 80°F with 0% chance of rain in Portland, OR today, but the seven-day forecast jumps to 96–98°F by Monday and Tuesday.

That's the PNW pattern in a nutshell — long stretches of mild weather punctuated by short, intense heat spikes. If you're germinating outdoors or hardening off seedlings, those spike days are your window to get plants into full sun and build real heat into the media. Don't waste them, and don't leave seedlings out unprotected once that heat breaks back down toward the 70s — you'll lose the momentum you just gained.

Why June and not earlier

You might think starting earlier gives you more growing time. In practice, Pachypodium started in April or May in the PNW often sit and stall because the ambient temps and light levels aren't enough to drive the heat the seeds need. June marks the point where daytime temps in most PNW growing areas are consistently reaching the upper 70s or low 80s — still not hot enough for outdoor germination, but warm enough that a heated indoor setup is much easier to maintain.

Coastal Oregon and Washington growers (Zone 8b–9): Your summers are mild. Outdoor Pachypodium cultivation is possible, but germination is best done indoors with bottom heat, and for the first season, a greenhouse or cold frame dramatically improves outcomes. Ambient outdoor temps in coastal areas rarely get hot enough for these plants to grow at full speed. Plan on indoor or protected growing for at least the germination phase and early seedling stage.

Inland Pacific Northwest growers in the Willamette Valley or Puget Sound lowlands (Zone 8a): You'll have stretches of genuinely warm summer weather — like the mid-90s push forecast for this coming Monday and Tuesday. Take advantage of them. Germinate indoors with heat mat support, then move seedlings outside to your warmest, most south-facing microclimate once daytime temps are reliably above 80°F. Walls, pavement, and south-facing overhangs create heat traps that can add 10–15°F to ambient temps — use them.

Higher elevation or inland Washington/Idaho border growers (Zone 7b): Your growing window is short enough that you're essentially treating Pachypodium the same way cold climate Zone 6 growers do. Indoor germination, indoor early development under grow lights, outdoor placement only during the warmest weeks of July and August. Your caudex development in year one will be modest, but it's achievable. Prioritize faster-growing species like P. lamerei and P. rosulatum rather than the slower, more temperamental dwarfs.

The light problem

The PNW's other challenge is light intensity. Pachypodium wants full sun — 6+ hours of direct sun with high UV intensity. PNW summers are long-day but not necessarily high-intensity. If your seedlings are growing but staying thin and pale rather than developing the compact, sturdy growth you're looking for, supplemental lighting is the fix. A T5 or LED grow light running 14–16 hours in addition to whatever natural light your setup gets will make a measurable difference in first-year caudex development.

Germination protocol

Same fundamentals as elsewhere in the country: shallow fast-draining media, surface or near-surface sowing, bottom heat at 88–92°F, humidity dome until germination. In the PNW, maintaining that soil temperature consistently is the key variable. A heat mat alone in a cool room may not get you there — monitor actual media temperature, not just air temperature in the room. A soil thermometer is worth using during the germination phase.

Fresh seed germinates in 5–10 days under good conditions. Older seed may take 2–3 weeks or not germinate at all. Don't give up on a tray too early — I've had stragglers come up at day 18–20 from older seed.

Overwintering in the PNW

First-year seedlings need to come inside when nighttime temps approach 50°F — that typically means late September for coastal areas, mid-September for inland zones. The overwintering protocol mirrors what cold climate growers use: reduce watering, keep temperatures above 55–60°F, provide grow light supplementation through the short-day months, and resume normal care in March or April as day length increases.

The advantage PNW growers have over true cold climate growers is that winters are mild enough that you're not running a heater constantly to keep your grow space viable. A cool but frost-free garage or basement with grow lights handles most of what you need.

Cheers,

Michael