It is not well known, though often noted by the Gardener's Monthly, that many plants are not hardy simply because they have too much or too little heat in summer time. The exact conditions of health will alone produce a constitution capable of bearing misfortune. Many of our hardy trees are tender in England through a deficiency of summer heat. In the severe winter of 1879-80, according to the London Garden, numberless beds of asparagus roots were totally destroyed, no doubt for want of healthy maturity the season before, for the plant will endure the severest American winter.