✨ Pinch the side buds, feed the roses one last time, watch echinacea run the show.
Disbudding Portland dahlias in July is the single move that turns a decent flower into a show stopper, and this dry 82°F week is the perfect window to do it. I'm also squeezing in the last nitrogen feeding on my roses before the July 15 cutoff, and watching the echinacea take over the middle of the border. Three very different flowers, one week to get all of them right.
This Week's Action List
- 1
Disbud dinner plate dahlias like 'Cafe au Lait' and 'Kelvin Floodlight' by pinching the two side buds flanking each terminal bud. Do it Tuesday or Wednesday morning while temps sit in the high 70s F, not Monday's 88°F peak. One bloom per stem draws energy into a single 8 to 10 inch flower instead of three mediocre ones.
- 2
Give roses their final nitrogen containing feed by Wednesday July 8, well before the July 15 cutoff. I use a balanced 5 to 5 to 5 organic blend at 1 cup per mature shrub, scratched into the top inch of soil and watered in with 2 gallons. Any nitrogen after mid July pushes tender growth that won't harden off before fall.
- 3
Deadhead echinacea 'Magnus' and 'White Swan' back to the next set of leaves every three days to keep the second flush coming through August. Leave a few late September cones standing for goldfinches, but for now, keep cutting. A sharp bypass pruner wiped with rubbing alcohol between plants stops any aster yellows from spreading.
- 4
Cut dahlias for the vase between 6 and 8 a.m. before Friday's 85°F afternoon, when stems are turgid and sugar loaded. Plunge stems immediately into a bucket of 100°F water and let them condition in a cool garage for at least 4 hours before arranging. Recut underwater at a 45 degree angle and they'll hold 5 to 7 days.
- 5
Deep soak rhododendrons and camellias once this week with 5 gallons per mature shrub applied slowly at the drip line Thursday evening. They're setting next spring's buds right now, and a dry July is when Portland gardeners quietly lose the show they were hoping for next April. Mulch with 2 inches of shredded leaves to lock the moisture in.
Frequently Asked Questions
How many side buds should I remove when disbudding dahlias in Portland?
Remove the two smaller side buds on either side of the central terminal bud on each stem, leaving one bud per stem. On exhibition types like 'Kelvin Floodlight' or 'Emory Paul' I also strip the top pair of leaves to give the bloom a longer clean stem for cutting. Do this when the side buds are pea sized, roughly 10 to 14 days before you want the flower to open.
Why can't I fertilize Portland roses with nitrogen after July 15?
Nitrogen pushes tender new shoots that need 6 to 8 weeks to harden before Portland's first frost around November 15. Feeding into late July or August produces soft growth that gets slammed by the first cold snap and invites cane dieback. Switch to a low nitrogen, higher potassium feed like 0 to 10 to 10 in August if you want to support root and bloom strength without triggering new canes.