You always hear the phrase that hostas are "shade-loving" plants. Of course, this is an incorrect statement since all plants require light at some level for photosynthesis. More correctly, hostas are "shade-tolerant' plants that can survive at lower light intensities.

Sunlight is also important for plants because it heats the leaf surface as causes evaporation (transpiration in plants) which helps pull water up from the roots. Plants that are adapted to the shade have vascular systems that are also adapted to a lower level of transpiration since they normally are not exposed to high intensity sunlight.

So, when you put hostas out in the sunlight, they may be asked to replace the water that evaporates off their leaves at a rate faster than their "pipe system" will allow. When this happens, the cells in the tissue furthest from the roots tends to die first. That is why this damage usually is most pronounced at the edges of leaves or in the variegation.

Many people rate hostas by leaf color in terms of the amount of sunlight they can manage. Yellow (H. 'Sun Power') or light green (H. 'Sum and Substance') will thrive in high light situations AS LONG AS THEY ARE GIVEN ADEQUATE WATER. This means preparing the soil with plenty of compost or other organic matter and regular irrigation during the hottest parts of the summer.

Next in line would be the green (H. Royal Standard') or blue (H. Blue Umbrellas') which can also thrive in high light levels with adequate water. We tend to put the blue hostas in more shade not because they will grow better but because they will stay blue longer into the season. Remember that the blue is due to a waxy coating on the leaf and this will wear off sooner in the bright sun.

Variegated hostas are often a case by case judgment. Certainly ones with wide areas of white variegation should be in the heavier shade or they will probably "melt out".

So, how do you manage sunburn? First and foremost, make sure your soil has plenty of organic matter in it. Second, avoid putting highly variegated hostas in areas that receive intensive sunlight especially in the later afternoon.

 

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