Cool Greenhouse #1

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Cool Greenhouse #1

Categories: Blog, Garden Guru

Powell Gardens’ Greenhouses each have a purpose in production and / or winter storage of unhardy plants in our collection. Greenhouse #1 is our “cool” greenhouse with low nighttime temperatures; it is a place to store warm temperate plants that require climates milder than ours but still are not tropical. Plants from deserts and Mediterranean climates (including California) or semi-tropical climates like the Gulf Coast or Southern Japan and China thrive in this greenhouse and usually relish being outdoors for our hot summers.

A peek in the door will reveal our collection of succulents from around the world. Most of these plants go on display outdoors around the Visitor Center in summer.

The bougainvillea is beginning to bloom and these dazzling floral beauties thrive in cool winter conditions. We have several and they go on display in containers or in the conservatory at other seasons when they are in peak bloom. Bougainvilleas like lean soils so be sure to not over-fertilize them or you will get all foliage and no flowers.

The Loquat (Eriobotrya japonica) that bloomed last fall is starting to form fruit that will ripen this spring. Loquats are fruit trees native to Southern China and Japan and our tree will go on display in the Heartland Harvest Garden for the summer. Loquats must have a cool but not frigid winter and thrive outdoors on the Gulf Coast or California. They make a beautiful container plan here!

Plants like this Chinese Redbud (Cercis chinensis ‘Don Egolf‘) are also spending the winter in Greenhouse 1. It is spring in the greenhouse and the redbud is in full bloom. This new cultivar of redbud is listed as zone 6 and was donated to us as a small plant. We will plant it on the grounds next spring–many plants gain hardiness as the plant gets more size. This new cultivar was bred by its namesake at the National Arboretum and its “attributes” are that it is a large shrub and sets no seed pods.

This green spiny shrub is a seedling of Hardy Orange (Poncirus trifoliata) that we grew from seed donated by the Missouri Botanical Garden. These hardy oranges are scheduled to be planted in the Heartland Harvest Garden where they will make an impenetrable hedge. Hardy orange has wonderfully fragrant flowers typical of all Citrus and sour “mini orange” fruit that can be concocted into a preserve that is edible. They are an important understock (roots to graft onto) for other varieties of citrus to improve hardiness. We do have an established ‘Flying Dragon’ cultivar of hardy orange growing outdoors on the south side of the Visitor Center.

Many of our stock plants of salvia spend the winter in greenhouse 1 and bloom beautifully in the shorter days of winter. The purple salvia is the cultivar ‘Paul’ and the vermilion cultivar is ‘Orange Louie.’ Both of these salvias go on display in the Hummingbird Garden for the summer.

A mist bench in Greenhouse 1 is a place to root cuttings of many of our specialty or stock plants. You can see cuttings of Viburnums just beginning to bud in the foreground, variegated schefflera in the middle and cuttings of magnolias towards the back. The brown mat you can see on the right is a heat mat that gives the trays of cuttings warmth to encourage root growth.
Flats of specialty plants we grew from seeds or cuttings fill available space. The “spiky” plants are a tray of Red Yucca (Hesperaloe parviflora) that we grew from an exceptionally hardy plant. Left are thriving cuttings of our groundcover Memorial Rose (Rosa wichuriana) from the Perennial Garden: destined for our Spring Plant Sale the first weekend in May. The back right plants are seedlings of buckeyes; both bottlebrush and red that will be used to beef up our collections.
Last is a seedling of a rare Missouri tree: Littlehip Hawthorn (Crataegus spatulata). This seedling will be destined for our collections as it gains some size. It has tiny red hips in fall that birds relish and some of the most beautiful fluted and cinnamon-silver mottled trunks of any plant hardy here.
Powell Gardens is completing two recycled greenhouses (from the former Longview Gardens) and still plans to assemble one more recycled greenhouse (donated from a local landscaper) to store the unhardy plants of the Heartland Harvest Garden. When all greenhouses are complete, Powell Gardens will have 10 greenhouses for production of seasonal plants and storage of its collection of over 15,000 accessioned plants. Keep watch for opportunities to visit them, as they are not open to the public except for special events — maybe next fall 2009?