Fall vegetable planting starts in earnest this week. Friday's forecast high near 90°F means germination timing is fussy, but nothing beats a November harvest.
This Week's Action List
- 1
Direct sow fall carrots (Napoli, Bolero, Yaya) and beets (Detroit Dark Red, Chioggia) by August 2 while soil is warm enough for fast germination. Pre soak the seed row for an hour, sow, then cover with a board or damp burlap for 4 to 6 days to keep the top inch from drying out in the 80°F afternoons.
- 2
Start fall brassica transplants (Winterbor kale, Lacinato, Gonzales cabbage, Belstar broccoli) in cell trays this week for setting out around September 1. Keep trays in bright shade during Friday's warmest hours since soil in a black cell tray can hit 100°F on a south facing bench.
- 3
Give roses their last summer feeding of the season if you have not already. Skip nitrogen entirely now and use a low nitrogen bloom formula, or nothing at all, so canes begin the slow shift toward dormancy on schedule.
- 4
Deep water fruit trees Wednesday or Thursday morning ahead of Friday's near 90°F peak. Run a slow trickle at the drip line for 2 to 3 hours to deliver roughly 15 to 20 gallons per mature tree, which pushes moisture into the 18 inch root zone where it actually matters.
- 5
Scout tomatoes every three days for late blight, focusing on the shaded interior canopy where lows near 55°F and morning dew still linger. Look for olive gray lesions on leaves and dark greasy patches on green fruit, and pull affected foliage into the trash, never the compost.
- 6
Check drip emitters plant by plant this week during peak demand. One clogged emitter on a July tomato produces a week of uneven watering, and uneven water is exactly how blossom end rot arrives on the fruit ripening right now.
- 7
Order garlic bulbs (Music, German Extra Hardy, Chesnok Red, Inchelium Red) from Filaree, Territorial, or Portland Nursery in the next two weeks. Good hardneck varieties for October planting sell out by early September, and grocery store garlic is a poor substitute in Zone 8b.
Frequently Asked Questions
When should I plant fall carrots and beets in Portland Oregon?
Direct sow fall carrots and beets between July 25 and August 10 in Portland Zone 8b. This window gives roots the 60 to 75 warm days they need to size up before daylight drops below 10 hours in mid October and growth effectively stalls. Sow later than August 10 and you will get greens, not roots.
Why can't I prune shrubs after late July in Portland?
Pruning stimulates a flush of new growth, and any tender growth pushed after July 25 will not have time to harden its bark and buds before Portland's first frost around November 15. Soft new tissue on a rhododendron, hydrangea, or Japanese maple in October is exactly what dies back in the first hard freeze. Save structural cuts for the dormant window between January and early March.
How do I keep fall brassica seedlings alive during Portland summer heat?
Start brassicas in cell trays kept in bright shade or under 30 percent shade cloth, and water once in the morning and once in the late afternoon during any day above 85°F. Soil temperature in the tray, not the seed itself, is what cooks a broccoli or kale start, so keep trays off dark surfaces and mist the foliage at dawn during the Friday heat spike.