✨ Late blight patrol, fall cabbage on the potting bench, drip lines finding their rhythm.
Portland late blight prevention shifts into serious mode this week as warm days and cool damp nights create textbook infection weather in Zone 8b tomato beds. Meanwhile the summer solstice on Sunday marks the quiet turnaround point where thoughtful gardeners start seeding fall brassicas indoors while everyone else is still fussing over June roses. Here is what actually deserves your attention between now and next Monday.
This Week's Action List
- 1
Inspect every tomato leaf twice this week for the first sign of late blight: greasy, water soaked spots on upper leaves that turn brown with a pale halo. An infected plant leaves the garden the same day, sealed in a trash bag, not the compost pile. Spores travel by wind and rain splash and can wipe out a bed in under a week.
- 2
Start fall brassica seeds indoors now: broccoli varieties like Belstar and Marathon, cabbages like Famosa, and any kale you want harvesting from October into February. Sow in 4 inch pots under lights, set out as transplants around July 20 to catch the cool fall growing window.
- 3
Switch tomato and pepper beds to soil level watering if you have not already. Overhead sprinklers on foliage in June are the single biggest late blight trigger in Portland gardens. Run drip lines or soaker hoses for 45 to 60 minutes between 5 and 8 am, twice a week, aiming for one deep inch.
- 4
Deadhead roses every 3 to 5 days, cutting back to the first outward facing five leaflet leaf. This is peak bloom in the City of Roses and neglected plants slide into a two week gap by early July. While you are in there, strip any yellowed lower leaves and bag them; black spot spores overwinter on fallen foliage.
- 5
Watch cucumber, zucchini, and pumpkin leaves for the dusty white patches of powdery mildew, which usually shows up in Portland gardens around the third week of June. Thin crowded vines for airflow and spray potassium bicarbonate on both leaf surfaces at the first pale spot. Neem oil works as a backup but scorches leaves above 85°F.
- 6
Side dress corn, tomatoes, and winter squash with a nitrogen source this week: blood meal at 2 tablespoons per plant, or a balanced 10 10 10 at the rate on the bag, scratched into the top inch of soil and watered in. Skip this on peppers and eggplant, which set more fruit when slightly lean.
- 7
Check container plants every single morning. A 12 inch pot in full sun on an east facing deck can go from moist to bone dry in 24 hours once daytime highs cross 78°F, and Portland is forecast to see mid 80s by Friday. Water until it runs freely from the drainage holes, not a splash on the surface.
- 8
Pinch the side buds off dahlia stems if you want long stemmed cutting flowers, leaving only the central bud on each stalk. Feed with a low nitrogen, high phosphorus fertilizer such as a 5 10 10 formula and stake now while the plants are still under two feet. Staking a six foot dahlia in August is a two person job with regrets.
Frequently Asked Questions
How do I know if my Portland tomato plant has late blight?
Look for irregular, greasy gray or brown patches on upper leaves, often with a fuzzy white edge on the underside in humid mornings. Stems develop dark lesions and fruit shows firm brown blotches that spread fast. Once confirmed, pull the plant, seal it in a trash bag, and put it in the garbage, not the compost.
When should I start fall broccoli and cabbage seeds in Portland?
Sow seeds indoors between June 15 and July 5 for transplants that go in the ground around July 20 to August 1. This timing puts heads maturing in October when Portland cools down and pest pressure drops. Starting later than early July usually means immature heads when the first hard rains arrive.
Can I still prune my rhododendron in mid June?
This is the very last week to shape rhododendrons and azaleas without sacrificing next spring's bloom. Buds for 2027 set in late June, so any pruning after roughly June 25 removes flowers. Stick to light shaping cuts now and save heavy renovation for right after bloom next May.
How often should I water established shrubs in Portland summer?
Established shrubs need about 1 inch of water per week delivered in one or two deep soakings rather than daily light watering. A slow hose at the drip line for 20 to 30 minutes twice a week trains roots to grow deep. Newly planted shrubs from this spring need closer to twice that through their first summer.