80 Days. If you like oxhearts as much as I do, then you may want to sample Coeur de Boeuf Jaune. This yellow oxheart is meaty, milder and sweet. it’s a great tomato for those not wanting a acidic tomato. This beauty is a full flavored tomato that can reach 14-16 ounces and is on the milder side. You’ll have the entire experience with this one! Coeur de Blue Jaune vines are skinny and have wispy leaves, they can reach 6 feet tall and have good disease resistance. Stake them well and harvest often. Great sauce, salsa and sandwich tomato! Great for market sales too.