Hydrangea quercifolia 'Pee Wee'

Hydrangea quercifolia 'Pee Wee' and western portion of the shadehouse in August 2022. Photo: SK Reid.

Summary

UC Davis is located in Davis, California, this site has a silty clay loam soil and plants are irrigated with potable water. More information about the field sites is located in the Nuts & Bolts section.

Pee Wee is an oakleaf-type hydrangea characterized by deeply lobed leaves with a prominent midvein in a shape reminiscent of oak species such as Quercus rubra. Pee Wee is a compact cultivar, typically listed as growing to 4-5’ high and wide. A deciduous species, Pee Wee leafs out in the spring with bright green new growth that turns to a medium green as it ages. In fall, most leaves will turn a deeper forest green then dark purple, with some taking on scarlet and orange coloration before dropping in late fall or early winter. In our field Pee Wee typically had a blousy, open appearance which in some cases resulted in an uneven form that weighed down overall appearance scores. We began with #1-sized containers and performed some initial pruning during the establishment year to encourage a fuller, more uniform shape. We expect that in a landscape the plants would fill out over time (as most H. quercifolia do) and this would not remain an issue. Beginning in May, panicles of white flowers appeared which contrasted attractively with the underlying chartreuse stem structure of the blooms. Flowering continued until July, though a handful of plants continued into August. For this species’ Floral Abundance scores, a 1 indicates at least one panicle with an open bloom on a plant, while the maximum score achieved would indicate at least 4-6 panicles of bloom uniformly distributed around the plant. 

Plants on all three treatments survived the entire season. Additionally, a majority of the individuals of this taxon were left in the field after the trial with a large portion of the remaining plants surviving the subsequent summer without any irrigation. This suggests significant drought tolerance: the ability to survive periods with little or no water. All three treatments met the minimum threshold of acceptability for our trial, achieving a mean overall appearance rating of 3 or higher over the deficit season. However, there was a marked decline in foliage and overall appearance scores in August and September for the 20% treatment. We hypothesize that the increase in the foliage and overall appearance scores in October resulted from the unseasonable rainfall and cooler weather in September creating conditions for a rebound in the 20% treatment. While evaluating the overall appearance ratings we found a significant difference between the 80% and 20% at 𝛼 = 0.05, but not between the 80% and 50%. Thus, we would recommend Pee Wee be irrigated at WUCOLS’ Moderate level in Region 2.

Basic Info

Growth and Quality Data

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Hydrangea quercifolia 'Pee Wee' on low water in November 2022. Photo: JA Sisneroz.