✨ Sow winter kale in June heat, thin the apples, chase the spider mites off the beans.
The last week of June is the exact window for Portland fall brassica seed starting, and if you miss it you are pushing kale, broccoli, and cabbage into November light they cannot use. Zone 8b gives you a long, mild fall, but only if transplants go in the ground by mid August at full size. This week the trays go on the potting bench, the apple crop gets thinned, and the bean patch gets a second look for spider mites.
This Week's Action List
- 1
Sow fall broccoli, cabbage, and kale in 4 inch pots or 72 cell trays this week. Aim for 6 to 8 weeks of growth before transplanting the third week of August. Reliable Zone 8b varieties include Belstar broccoli, Deadon cabbage, and Winterbor kale.
- 2
Germination stalls above 85 degrees F, so put brassica trays on the north side of the house or under 30 percent shade cloth. Bottom water the trays and keep the surface damp until cotyledons emerge, usually four to six days at Portland's late June soil temperatures.
- 3
Thin apple and pear fruit to one fruit every 6 inches along the branch. Portland trees routinely set five times what they can size up, and unthinned trees give you marble sized fruit and broken scaffolds by August. Do it before the fruit hits ping pong ball size, which is right now.
- 4
Spider mite pressure jumps once daytime highs cross 80 degrees F. Tap a bean or cucumber leaf over a sheet of white paper. If specks crawl, spray the undersides with insecticidal soap at dusk and repeat in five days. Overhead rinse the foliage midmorning on hot days to knock populations down.
- 5
Sow a second succession of bush beans direct into warm soil this week for a September harvest. Provider and Jade germinate reliably at 65 degree F soil, which most Portland beds are holding right now. Space seeds 3 inches apart in rows 18 inches apart.
- 6
Side dress tomatoes, corn, and winter squash with a balanced organic fertilizer like 5 5 5 at one cup per plant, scratched into the top inch of soil and watered in. Skip high nitrogen products on tomatoes now, they push leaves at the expense of fruit set.
- 7
Deadhead roses every 3 to 5 days, cutting to the first outward facing five leaflet leaf. This is also the last week to prune spring blooming rhododendrons and lilacs. After early July their flower buds for next spring are set, and any cut you make now is a bloom you lose in April.
- 8
Check container plants every morning. A 12 inch pot in full sun burns through its water in 24 hours once highs hit 80 degrees F, and blossom end rot on container tomatoes almost always traces back to one skipped day. Water until it runs from the drainage holes, then stop.
Frequently Asked Questions
When should I start fall broccoli and cabbage seeds in Portland?
The last week of June through the first week of July is the sweet spot for Zone 8b. That gives transplants 6 to 8 weeks of indoor or shaded growth before going into the ground by mid to late August, which lines up heads with the cool October weather brassicas want. Sow later than mid July and you risk immature heads when the light fades in November.
Why are my brassica seeds not germinating in June?
Brassica seed germination drops sharply above 85 degrees F, and a sunny Portland windowsill or greenhouse easily hits 90 degrees F this time of year. Move trays to a shaded outdoor bench or the cool north side of the house, keep the soil surface consistently damp, and you should see cotyledons in four to six days.
How do I know if I have spider mites on my Portland vegetables?
Look for fine yellow stippling on the tops of leaves and a dusty webbing on the undersides, especially on beans, cucumbers, and tomatoes during heat spells. Confirm by tapping a suspect leaf over a sheet of white paper and watching for moving specks the size of pepper grains. Insecticidal soap on the undersides of the leaves at dusk, repeated in five days, knocks them back without harming bees.
Is it too late to prune rhododendrons in Portland at the end of June?
This is the final week. Rhododendrons and other spring blooming shrubs set their flower buds for next year in early to mid July, so any pruning after the first week of July trades away April 2027 flowers. If you still need to shape a rhododendron, do it now and stop before the calendar flips.