Rose City Roots

Gardening in Portland since 1996.

Portland fall bulb planting bed prepped with compost and daffodil bulbs sorted nearby in autumn light

Portland Fall Bulb Planting Prep and a Warm Weekend Ahead

🔗 Share

Portland fall bulb planting kicks into gear this week, but with soil still holding summer warmth in the mid 60s, the job right now is prep, not planting. Get beds forked and amended by the weekend so tulips and daffodils can go in the ground the moment soil temps drop under 60°F in mid October.

This Week's Action List

  1. 1

    Fork 2 to 3 inches of compost and a handful of bone meal per square foot into any bed slated for tulips, daffodils, or alliums. Warm soil this week means bulbs will rot if you plant now, so stage the amendments and let the bed settle for two weeks before the bulbs actually go in.

  2. 2

    Botrytis gray mold is the real threat on dahlias with overnight lows in the low 50s and heavy morning dew. Walk the dahlia rows every couple of days and pinch off any mushy brown petals or leaves at the base, dropping them in the trash bin, not the compost.

    Botrytis gray mold is the real threat on dahlias with overnight lows in the low 50s and heavy morning dew. Walk the dahlia rows every couple of days and pinch off any mushy brown petals or leaves at the base, dropping them in the trash bin, not the compost.
  3. 3

    Thursday and Friday look like an unseasonable stretch near 80°F if the forecast holds. Deep water any shrubs planted in the last four weeks with 3 to 5 gallons at the root ball Wednesday evening, because established plants can coast but new rhododendrons and camellias cannot.

  4. 4

    Overwintering spinach, mache, and claytonia can still go in the ground this week if you sow by Wednesday. Broadcast into a raked seedbed, water in, and cover with floating row cover to keep the resurgent slugs off the germinating seedlings.

  5. 5

    Slugs come back hard in this weather pattern of cool damp nights and warm afternoons. Scatter iron phosphate bait (Sluggo or store brand) around lettuce, brassica seedlings, and any hosta crowns you want to see again next spring. The trusted tuna can filled with beer is still my preferred method. Check out our tutorial on managing these pests.

    Slugs come back hard in this weather pattern of cool damp nights and warm afternoons. Scatter iron phosphate bait (Sluggo or store brand) around lettuce, brassica seedlings, and any hosta crowns you want to see again next spring. The trusted tuna can filled with beer is still my preferred method. Check out our tutorial on managing these pests.
  6. 6

    Do not prune shrubs yet, even if they look ragged after a dry summer. Cuts made in early October push tender new growth that will get slammed by the first hard frost in November. Sharpen your bypass pruners with a diamond file instead and wait for true dormancy.

  7. 7

    Cover crop windows are closing fast for tender species. Sow crimson clover, fava beans, or a rye and vetch mix into any empty vegetable bed by October 5, water once, and let the fall rains take over from there.

  8. 8

    Order garlic and shallot bulbs this week if you have not yet. The prime Portland planting window closes around October 10, and hardneck varieties like Music, Chesnok Red, and Spanish Roja sell out at Portland Nursery and Concentrates NW by early October in most years.

    Order garlic and shallot bulbs this week if you have not yet. The prime Portland planting window closes around October 10, and hardneck varieties like Music, Chesnok Red, and Spanish Roja sell out at Portland Nursery and Concentrates NW by early October in most years.

Frequently Asked Questions

When should I plant tulip bulbs in Portland Oregon?

Wait until soil temperatures drop below 60°F, which typically happens in mid to late October in Portland. Planting into warm September soil invites bulb rot and fungal problems. Prep beds now with compost and bone meal so you are ready to plant the moment temperatures cooperate.

Is it too late to sow cover crops in Portland in late September?

No, but you are close to the deadline for tender species like crimson clover and fava beans. Sow by the first week of October so seedlings establish before hard frost. Winter rye and hairy vetch tolerate later sowing into mid October if you miss the window.

Why are my dahlia flowers turning brown and mushy?

That is almost certainly botrytis gray mold, which thrives in Portland's cool damp fall nights. Remove affected blooms and foliage promptly and trash them rather than composting. Improve air circulation by thinning crowded stems and stop overhead watering entirely at this point in the season.

Should I water my garden this week with 80°F temperatures returning?

Established plants are fine, but anything planted in the last month needs a deep drink before Thursday's warm up. Focus on new shrubs, fall transplants, and container plantings with a slow soak at the root zone. Skip the lawn and established perennials, which are already shifting into dormancy.