- Variety Info
- Sowing Info
- Growing Info
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Variety Info
Days to Maturity: 110–130 days
Family: Alliaceae
Type: Long-day sweet storage onion. (Learn more)
Native: Exists only in cultivation
Hardiness: Biennial grown as an annual
Exposure: Full sun
Plant Dimensions: 3 1/2" to 6" globe-shaped bulbs with 12" to 16" tops
Variety Info: Large, 3 ½"–6", up to 2 lbs., pale yellow, globe-shaped bulbs with coppery wrapper; 12"–18" tops. 'Yellow Sweet Spanish Utah' is a bulbing, yellow, long-day onion with a moderate storage period.
Attributes: Frost Tolerant
Sowing Info
When to Sow Outside: 4 to 6 weeks before your average last frost date, or as soon as soil can be worked; when soil temperature is at least 45°F.
When to Start Inside: RECOMMENDED. 10 to 12 weeks before your average last frost date. Transplant outdoors 4 to 6 weeks before your average last frost date. The earlier the start, the bigger the bulb. Ideal soil temperature is 60°–85°F.
Days to Emerge: 7–15 days
Seed Depth: ¼"
Seed Spacing: A group of 2 seeds every 6"–8"
Row Spacing: 12"–16"
Thinning: When 2" tall, thin to 1 every 6"–8"
Your hardiness zone is
Growing Info
Harvesting: When onion tops have fallen over and turned yellow or brown, they are ready for harvest. Harvest in the morning, lifting onions with a garden fork. Dry them in the garden in the sun for 2 to 3 days, lightly covering the bulbs with straw, or the tops of other onions to prevent sunscald. Cure onions for 3 to 7 days in a dry area with good air circulation. Once dry, cut the roots to 1/4", and the greens to 1" to create a seal, preventing decay.
- DVerified BuyerRated 3 out of 5 stars9/18/2561% germination rate
Planted 23 seeds on 8/29, 14 germinated very quickly. The others never germinated. Planted the 14 onions outside 9/18.
Which best describes you as a gardener? IntermediateBIBotanical Interests9/19/25Hey D,
Thank you so much for taking the time to share your thoughts in a review. I've reached out to you via email to offer assistance. Your feedback is invaluable to us, and we are committed to ensuring your experience is positive. Thank you once again for your input. Keep on growing 🌻️
- DVerified BuyerRated 5 out of 5 stars9/2/25Very Fast Germination
Planted 8/29, sprouted 9/2
Which best describes you as a gardener? IntermediateBIBotanical Interests9/2/25Hey D,
Thank you so much for sharing your amazing germination results with our Yellow Sweet Spanish Utah Bulb Onion Seeds! We absolutely love hearing that you got such incredibly fast sprouting - just 4 days from planting to emergence is fantastic! That's exactly the kind of vigorous performance these quality onion seeds are known for. There's nothing quite like seeing those first little green shoots pop up so quickly - it really gets the growing season off to an exciting start! With germination like that, you're definitely on track for some beautiful, large sweet onions. Keep on growing 🌻️
- Jayne S.Verified BuyerRated 5 out of 5 stars2/8/255 Stars
This company does it all for me. Great seeds that always meets my expectations. Beautifully artistic seed packets for that inspiration motivation. (I even made a framed collage of some of the seed packets for my wall. I got many compliments on it too!). Great customer service. Onions are extremely easy to grow. These have great flavor.
- Kathy L H.Verified BuyerRated 5 out of 5 stars5/20/245 Stars
They have all come up! I am excited about my garden. I also have a butterfly garden. I like more zinnias in my Hummingbird Haven seeds. I was disappointed there were not as many.
Which best describes you as a gardener? Beginner - Michael L.Verified BuyerRated 1 out of 5 stars4/10/241 Star
I think something must have happened to this packet. I started four different varieties of onions, all at the same time, with the same soil, under the same conditions. The other varieties were fine, but not a single one of these Yellow Sweet Spanish Utah germinated.
Which best describes you as a gardener? Intermediate