Rainline Garden
When to plant zinnias in Klamath Falls, OR
Plant zinnias from seed, directly in the garden in Klamath Falls, Jun 16 – Jul 28.
- Difficulty
- Easy
- Sun
- Full sun
- Spacing
- 9 to 12 inches apart
- Planting depth
- ¼ inch deep
- Frost
- Killed by frost
- Flowers
- Blooms about 60 to 75 days after sowing
Why these dates
Klamath Falls's typical last spring frost is June 9. Frost kills zinnias, so planting starts once frost risk drops, around June 16. Keep row cover or a frost blanket handy for the first couple of weeks, since a late frost is still possible.
High desert and mountains. Central and high eastern Oregon. Frost is possible almost any month. Use row covers, wall-o-water or cloches for warm crops, and choose short-season varieties.
How to grow zinnias in Klamath Falls
- Prepare the bed: loosen the soil and mix in an inch or two of compost.
- Plant seeds Jun 16 – Jul 28, ¼ inch deep, 9 to 12 inches apart.
- Keep the soil evenly moist until sprouts appear, which can take one to three weeks in cool soil.
- Harvest: Cut when stems are stiff right below the flower (give it a gentle wiggle test). Cut long stems often; the more you cut, the more they bloom.
Key numbers
- 70–80°FSoil to sprout
- 5.5–7.5Soil pH
- 60–75Days to bloom
- Powdery mildewBiggest risk
Growing notes
What makes the difference in Northwest gardens, in plain language.
Wait for warm weather
Zinnias come from hot, dry regions and do nothing in cold soil. Seeds sown too early west of the Cascades often rot, and seedlings sit stunted and yellow. Sow once the soil is warm and nights are mild, usually late May to early June on the west side. They catch up fast: a sowing in early June often blooms by midsummer.
You can start them indoors a few weeks early, but transplant them young, since older seedlings don't like root disturbance.
Pinching and cutting
When a young plant is about a foot tall with three or four pairs of leaves, pinch out the top just above a leaf pair. The plant branches, and those branches give more stems and longer ones for cutting.
Cut flowers often and cut deep, down to a leaf pair low on the stem, so new branches have room to grow. Check for ripeness with the wiggle test: a stem that stays stiff just below the flower will last in the vase, while a floppy one wilts quickly.
Mildew, and east vs west
Powdery mildew coats leaves with white powder in late summer, when warm days and cool, damp nights alternate, a typical west-side pattern. Space plants for airflow, water the soil instead of the leaves and choose resistant varieties like Zahara. It looks bad but rarely stops flowering.
East of the Cascades, zinnias thrive in the heat and mildew is less of a problem, though steady water keeps them blooming. Slugs on young seedlings are the bigger west-side issue.
Common questions
When is the last frost in Klamath Falls, OR?
Typically June 9. In 9 years out of 10, frost is over by June 26. These are 1991–2020 NOAA climate normals for Klamath Falls Airport.
Is it too late to plant zinnias in Klamath Falls?
The spring planting window runs through July 28. Later plantings may not have time to bloom well before the first fall frost, which usually arrives around September 18.
When do zinnias bloom?
Blooms about 60 to 75 days after sowing. Cut when stems are stiff right below the flower (give it a gentle wiggle test). Cut long stems often; the more you cut, the more they bloom.
Should I pinch my zinnias?
Yes, for cut flowers. Pinch the top when plants are about a foot tall; they'll branch and give many more long stems. Skip pinching on dwarf bedding types.
What is the white powder on my zinnia leaves?
Powdery mildew, a fungus common in late summer. Remove the worst leaves, water at the base and give plants more room. Next year, try resistant varieties like Zahara.
Why don't my zinnias last in a vase?
They were likely cut too early. Use the wiggle test, cut in the cool of the morning, strip the lower leaves and change the water often. Zinnias prefer clean water without much floral preservative.
Also plant in Klamath Falls around the same time
Radishes
Lettuce
Carrots
Beets
Kale
Broccoli
Cabbage
Swiss chardPlanting dates for zinnias in nearby areas
- Bend and Redmond, OR Jun 16 – Jul 28
- Burns, OR Jun 18 – Jul 30
- Prineville, OR Jun 8 – Jul 20
- Madras, OR May 26 – Jul 7
- Lakeview, OR Jun 11 – Jul 23
- Baker City, OR Jun 1 – Jul 13
Full planting calendar for Klamath Falls · Zinnias in every city