Glass Gem

Family: Poaceae Grain Vegetable

Planting Schedule

Provide your location or planting zone to unlock dates and add Glass Gem to a garden.

Feel the glassy shimmer before you even harvest—Glass Gem corn forms jewel-bright kernels that catch the light like faceted opal, with a spectrum of amber, cream, rose, and deep blue-green.

The kernels are pleasantly tender with a sweet, fresh snap, making them a standout for showy fresh use and for vibrant color in seasonal displays, salsas, and pickled accents. Grow it for the garden spectacle as much as the flavor—each ear becomes a living mosaic ready to brighten your table.

Light: Full SunMaturity: 90 DaysHabit: Upright

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Glass Gem Planting Dates by USDA Zone

Estimated US hardiness-zone windows for sow, transplant, and harvest. Enter a US ZIP above for exact local dates, or open a zone below.

Zone	Start Indoors	Sow / Transplant	Harvest
Zone 1a	Protected Environment Only
Zone 1b	Protected Environment Only
Zone 2a	Direct Sow	May 25th	Aug 23rd – Aug 29th
Zone 2b	Direct Sow	May 15th	Aug 13th – Aug 25th
Zone 3a	Direct Sow	May 15th	Aug 13th – Sep 1st
Zone 3b	Direct Sow	May 19th	Aug 17th – Sep 21st
Zone 4a	Direct Sow	May 15th	Aug 13th – Sep 24th
Zone 4b	Direct Sow	May 13th	Aug 11th – Sep 27th
Zone 5a	Direct Sow	May 8th	Aug 6th – Sep 30th
Zone 5b	Direct Sow	May 4th	Aug 2nd – Oct 5th
Zone 6a	Direct Sow	May 1st	Jul 30th – Oct 10th
Zone 6b	Direct Sow	Apr 25th	Jul 24th – Oct 16th
Zone 7a	Direct Sow	Apr 20th	Jul 19th – Oct 20th
Zone 7b	Direct Sow	Apr 10th	Jul 9th – Oct 28th
Zone 8a	Direct Sow	Apr 1st	Jun 30th – Nov 5th
Zone 8b	Direct Sow	Mar 23rd	Jun 21st – Nov 12th
Zone 9a	Direct Sow	Mar 6th	Jun 4th – Nov 26th
Zone 9b	Direct Sow	Feb 9th	May 10th – Dec 9th
Zone 10a	—	Oct 1st	Dec 30th – Feb 28th
Zone 10b	—	Oct 1st	Dec 30th – Feb 28th
Zone 11a	—	Oct 1st	Dec 30th – Feb 28th
Zone 11b	—	Oct 1st	Dec 30th – Feb 28th
Zone 12a	—	Oct 1st	Dec 30th – Feb 28th
Zone 12b	—	Oct 1st	Dec 30th – Feb 28th
Zone 13a	—	Oct 1st	Dec 30th – Feb 28th
Zone 13b	—	Oct 1st	Dec 30th – Feb 28th

Crop Details

Trait	Value
Days to Maturity	90
Sun Requirements	Full Sun
Growth Habit	Upright
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	60
Min Soil Temp (°F)	55
Min Night Temp (°F)	28
Harden Off (days)	Not Required

Culinary Notes

Chef's Note

Glass Gem sweet corn is all about that fresh snap—harvest right and treat it gently so it doesn’t slide from crunchy to starchy. Its candy-sweet, milky sweetness takes heat, acid, and smoke beautifully, which is why it shines in salsas and blistered skillet corn over anything creamy or tangy.

Best Uses

shaved off-the-cob into quick salsas where the kernels stay crisp
briefly sautéed or blistered for a char-sweet contrast without turning starchy
swirled into limey ceviche-style corn bowls
lightly pickled corn for tangy, jewel-toned pops in tacos and grain salads

Flavor Profile

bright, sweet corn flavor tender kernels with a clean, juicy snap mild, milky starchiness with a fresh finish color-forward crunch (amber to cream)

Kitchen Pairings

lime cilantro chili (jalapeño or serrano) cotija or queso fresco smoked paprika butter or crema

Frequently Asked Questions

What pest or disease most often affects Zea mays var. saccharata (glass gem corn), and what should I do?

Watch for corn earworm (Helicoverpa) once silks appear—damage often starts at the tip of ears. Apply a labeled BT (Bacillus thuringiensis) product or an earworm-targeted corn insecticide following the label timing when fresh silks first show and repeat as directed. Also remove and destroy any visibly moldy or rotting ears early to reduce spread of ear rots (common in humid weather).

How often should I water glass gem corn during the main growing phase?

During active growth (after plants are established and before ears mature), keep soil evenly moist with about 1–1.5 inches of water per week, increasing during hot spells. Water deeply so moisture reaches the root zone, especially around tasseling and silking, because inconsistent moisture then can cause poor kernel set. Mulch to reduce drying, and avoid letting the soil swing from very dry to waterlogged.

How can I tell when Zea mays var. saccharata (glass gem corn) is ready to harvest?

Harvest when silks are brown and dry, and kernels look fully developed, tightly packed, and glossy—typically around 80–100 days depending on conditions. Press a kernel with your thumbnail: it should release milky “juice” (not clear water), and the kernel color should match the variety’s mature jewel-like pattern. For the best sweetness and tenderness, pick in the morning and use soon after harvest.