Here is a list of some appropriately-named-for-Halloween plants from this website:
http://plantsbulbs.suite101.com/article.cfm/halloween_themed_garden_plants
Acer palmatum 'Purple Ghost', 'Red Spider', 'Bloodgood' and 'Sister Ghost' - Zones 5-8. These Japanese maples all have unusual names that are more than suitable for a Halloween themed garden. As an added bonus, all Japanese maples have brilliant fall color.
Aralia (Fatsia japonica) 'Spider's Web' - Zones 6-9. This fall-blooming plant is a large shrub or can be pruned into a small tree and has unique variegated foliage all season.
Blanket Flower (Gaillardia) 'Kobold (Goblin)' and 'Gold Goblin' - 'Goblin' and 'Gold Goblin' are both long-blooming perennial plants with bright flowers and drought tolerance.
Canna 'Lucifer' - A dwarf canna only 3-4' tall with bright red-orange flowers that contrast against the broad green leaves.
Dianthus 'Bewitched' - Zones 3-8. A low-growing dianthus great for edging and containers, this dianthus has fringed, pink flowers with bright purple-red centers.
Eggplant 'Casper' - An unusual variety of eggplant, this plant produces fruit that is pale white instead of bright purple.
Elderberry (Sambucus *****) 'Witches Broom' - Zones 5-8. A great year-round shrub with ornamental winter berries, 'Witches Broom' features a dwarf stature of only 8" perfect for small borders.
Firethorn (Pyracantha angustifolia) 'Gnome' - Zones 5-9. Firethorn is a compact, deciduous shrub bright orange winter berries.
Geranium 'Tiny Monster' - Zone 4-8. Despite the name, this cranesbill isn't horrific in anyway, but the prolific pink flowers with magenta veining are beautiful additions to any garden.
Hosta 'Red October' - This hosta has medium green, lance-shaped leaves with bright red stems.
Hyssop (Agastache) 'Black Adder' - Zone 6-9. Dark purple flowers all summer and into fall are a favorite of butterflies.
Japanese Bitter Orange (Poncirus trifoliata) 'Flying Dragon' - Hardy to zone 5. Twisted branches and spiny stems make this ornamental tree an unusual addition to the Halloween themed garden and provide a unique winter silhouette.
Japanese Painted Fern (Athyrium nipponicum) 'Ghost' and 'Ursula's Red' - Zones 3-8. Great for part to deep shade with consistently moist soil. Japanese ferns naturalize well.
Lavender (Lavandula angustifolia) 'Graves' - Zones 5-11. The 'Graves' lavender makes a nice addition for a Halloween themed garden because of its name, but makes a great plant for any bed or border because the flowers of this herb are lighter purple than other lavender cultivars.
Oriental Lily (Lilium) 'Alchemy' - This trumpet lily is perfect for brewing up a Halloween themed garden with its large, creamy-orange colored flowers.
Pumpkin 'Casper' - Another white fruiting plant for the garden, this pumpkin has huge white pumpkins that are perfect for the Halloween themed garden.
Rosa 'Banshee' - An old garden rose with fabulous scented pink flowers.
Heath, Spring Heath (Erica darleyen) 'Ghost Hills' - Light silvery-green foliage with cream-colored tipped foliage in the spring.
Tiarella 'Crow Feather', 'Skeleton Key' and 'Jeepers Creepers' - Zones 4-9. 'Crow Feather' has bright green foliage with dark red, almost black markings along the veins that resemble feathers. 'Jeepers Creepers' has bold winter foliage contrast with green, orange or reddish colored leaves and 'Skeleton Key', while less colorful, has fine cut foliage that is unusual for tiarella plants.
