Thanks for the question.

Leaves turning purple typically mean that they are losing chlorophyll and underlying purple pigments are seen. A loss of chlorophyll is often indicative of some type of stress to the plant. This stress may be caused by over-watering, under-watering, and/or a lack of one or more essential nutrient. Generally insufficient phosphate will cause this purple appearance. However this does not necessarily mean that this deficiency exists in the soil but is in the plant itself. Phosphate enters your plant when dissolved in soil water.  This water is taken up by the roots and transported throughout the plant.  If the root system cannot do this, purple leaves will develop.  This is generally seen when over-watering of the plant occurs. Do not water either of these two plants unless the soil is dry to the touch down to about two or three inches. If you have just observed these conditions in your two plants, they may simply have been caused by cool and wet conditions over the last couple of weeks.  In looking at recent temperatures in Big Stone County, I see that there have night temperatures in the mid to low 30's.  These environmental conditions can create stressful conditions for plants.   See the following for more information on these and related points, including remedial actions:

https://www.gardeningknowhow.com/plant-problems/environmental/leaves-turning-reddish-purple.htm

https://www.gardeningknowhow.com/plant-problems/environmental/leaves-turning-reddish-purple.htm - :~:text=When you notice a plant,energy, sugars and nucleic acids.&text=If the soil is cool,may develop in some plants.

https://todayshomeowner.com/problem-with-purple-leaves-caused-by-phosphorus-deficiency/

https://homeguides.sfgate.com/high-phosphorus-foods-plant-42920.html

By the way, your hydrangea should be pruned only to a minimal extent if you want an abundance of blooms. Flower blossoms develop on both old and new wood. 

See:

https://plantaddicts.com/lets-dance-can-do-hydrangea/ - :~:text=Pruning Let's Dance Can Do,any time of the year.

Jacob’s Ladder, especially its flowers, is a beautiful plant. See:

https://www.thespruce.com/growing-spring-blooming-jacobs-ladder-1402847 - :~:text=Jacob's ladder (Polemonium caeruleum) is,that are the real attraction.

If the conditions of these two plants do not change within the next few weeks as temperatures rise, please get back to us so that we can revisit the situation.

Good luck