Jack Ice Iceberg or Crisphead Lettuce - Organic


Jack Ice Iceberg or Crisphead Lettuce - Organic

(48 days) Frank Morton discovered early hardy Jack Ice in a random sample of Reine des Glaces. A head of iceberg is a treat in the summer heat, but the class is well-known for maturing at a glacial pace. Dark green 11" Jack Ice delivers a perfect uniform “headless iceberg” crispleaf early in the season, giving growers and gardeners the expected “ice” crunch and sweetness without the wait. Jack’s slightly pebbled extra-toothed fringed leaf and broad-centered whorl is suited for salad-mix cuts or full head harvest. High resistance to DM and TB, slow bolting, and with overall disregard for temperature extremes. Frank describes this new “Jack of all salad trades” best: “Crisp as frost, freeze and heat tolerant, resistant to SC, great mild taste, a very good lettuce.”

2714 Jack Ice - Organic
Item Discounted
A: 1g for $2.50  
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B: 4g for $6.30  
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C: 14g for $11.00  
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D: 28g for $16.00  
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E: 112g for $56.00  
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Additional Information


Lactuca sativa

All lettuce is open-pollinated.
1 gram packet sows 25 ft; 2 grams, 50 ft; 1 oz, 500–700 ft. Varieties average 875 seeds/1g pkt, or 1,750 seeds/2g packet.

Culture: May be started indoors in March and at regular intervals thereafter, or sowed outdoors as soon as ground can be worked. Many varieties won’t germinate in soil temperatures above 75° and most shut down above 80°. Where available, we present data here from a California germination experiment at 84°.

Hardy. All save icebergs tolerate heavy frost. Grow best in cool weather with ample moisture, many kinds suffer bottom rot and tipburn in heat; select summer varieties carefully. Use shade cloth to keep summer lettuce tender and sweet longer. Sesquiterpene lactones produced in the latex render lettuce bitter when it bolts.

Sow every 2 weeks for continuous supply. Lettuce will not head unless thinned frequently and ruthlessly to final distance of 1'. Heavy nitrogen feeders.

Minimum germination soil temperature 35°, optimal range 40–80°.

Days to maturity are from direct seeding.


  • BOR: Bottom Rot
  • DM: Downy Mildew
  • LMV: Lettuce Mosaic Virus
  • PM: Powdery Mildew
  • SC: Sclerotinia
  • TB: Tipburn
  • X: Xanthemonas

Pest: Aster Leafhopper (vector for Aster Yellows disease)
Cultural controls: control perennial broadleaf weeds near lettuce plantings, plow lettuce fields immediately after harvest.

Pest: Slug
Cultural controls: avoid mulch or nearby grassy areas.
Material: Sluggo

Disease: Bottom Rot
Cultural controls: rotate with grass-family green manures, plant in well-drained soil or on raised beds, more upright varieties escape infection.

Diseases: Downy Mildew, Grey Mold, White Mold
Cultural controls: rotation, reduce duration of leaf wetness, plant parallel to prevailing winds, use wide spacing, control weeds, use well-drained fields in spring and fall.
Material: Actinovate