Planting Zinnias from seed - Ask Extension
When is it safe to plant zinnia seed in the Willamette Valley and how much preparing is needed for the soil? Also, will zinnias do ok in a morning su...
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Planting Zinnias from seed #864875
Asked April 17, 2024, 2:10 PM EDT
When is it safe to plant zinnia seed in the Willamette Valley and how much preparing is needed for the soil? Also, will zinnias do ok in a morning sun spot or do they need full sun? Thanks!
Benton County Oregon
Expert Response
Dear Gardener,
Thank you for contacting us about growing zinnias. We are still getting frost warnings in the Willamette Valley even though our average last frost date is behind us. I recommend that you wait until the middle of May to plant your seeds so the soil is thoroughly warm. Soil temperature is more important than air temperature.
If you want a head start, start them indoors now using a soilless mix. Soak the seed overnight before planting to reduce the time it takes for germination. Use peat pots or make pots from newspaper. Thin them to 1 plant per peat pot to allow for proper spacing and transplant the entire pot into your garden bed once the seedlings reach a height of 1 inch. Tear off any exposed part of the pot so it doesn't act like a wick and dry out your plant.
When planting outdoors, be sure the soil is completely free of weeds and grass and rake it smooth. Compost is not necessary but if you have soil problems, please write again and I can advise you.
Zinnias prefer well-draining soil and at least 6 hours of sun each day. They may grow with less sun, but the blooms will not be as showy and may develop fungal diseases. Powdery mildew is a common disease of zinnias, so water at the base of the plant to keep the foliage dry. Soaker hoses work well. Water deeply a few times a week, preferably in the morning, to reduce the risk of fungal diseases.
Zinnias should be deadheaded regularly. Trim off flowers that are brown or wilting to encourage more blooms.
I hope this information is helpful. Write again whenever you have gardening questions.
Thank you for contacting us about growing zinnias. We are still getting frost warnings in the Willamette Valley even though our average last frost date is behind us. I recommend that you wait until the middle of May to plant your seeds so the soil is thoroughly warm. Soil temperature is more important than air temperature.
If you want a head start, start them indoors now using a soilless mix. Soak the seed overnight before planting to reduce the time it takes for germination. Use peat pots or make pots from newspaper. Thin them to 1 plant per peat pot to allow for proper spacing and transplant the entire pot into your garden bed once the seedlings reach a height of 1 inch. Tear off any exposed part of the pot so it doesn't act like a wick and dry out your plant.
When planting outdoors, be sure the soil is completely free of weeds and grass and rake it smooth. Compost is not necessary but if you have soil problems, please write again and I can advise you.
Zinnias prefer well-draining soil and at least 6 hours of sun each day. They may grow with less sun, but the blooms will not be as showy and may develop fungal diseases. Powdery mildew is a common disease of zinnias, so water at the base of the plant to keep the foliage dry. Soaker hoses work well. Water deeply a few times a week, preferably in the morning, to reduce the risk of fungal diseases.
Zinnias should be deadheaded regularly. Trim off flowers that are brown or wilting to encourage more blooms.
I hope this information is helpful. Write again whenever you have gardening questions.
