Barbara J. Bromley, Mercer County Horticulturist 94
The following annual plants are tolerant of hot summer temperatures. This adaptation makes them useful for bed planting in street dividers, in exposed containers, by parking lots, and in other hot locations. Some, like wax begonias, tolerate heat better if their roots are kept cooler by mulching.
Begonia, nicotiana, pastel salvias, spider flower, and creeping zinnia are tolerant of light to moderate shade.
- Amaranthus species (Joseph’s coat, love-lies-bleeding)
- Begonia x semperflorens-cultorum (wax or fibrous-rooted begonia)
- Capsicum annuum (ornamental pepper)
- Catharanthus roseus, also Vinca rosea (Madagascar periwinkle)
- Celosia cristata (crested and plumed cockscomb)
- Cleome hasslerana (spider flower)
- Convolvulus ticolor (dwarf morning glory)
- Coreopsis tinctoria (annual coreopsis, calliopsis)
- Cuphea ignea (firecracker plant, Mexican cigar plant)
- Dahlia hybrids (dahlia)
- Dyssodia tenuiloba (Dahlberg daisy)
- Elchscholzia californica (California poppy)
- Euphorbia marginata (snow-on-the-mountain)
- Eustoma grandiflornm, also Lisianthus (Prairie gentian)
- Gomphrena globosum (globe amaranth)
- Grasses
- Helianthus species (sunflowers)
- Kochia scoparia trichophylla (summer cypress, burning bush)
- Mirabilis jalapa (four-o’clock)
- Nicotiana alata (flowering tobacco)
- Petunia x hybrida (petunias)
- Portulaca grandiflora (portulaca, moss rose)
- Rudbeckia hirta (gloriosa daisy)
- Salvia species (sage, salvia)
- Sanvitalia procumbens (creeping zinnia)
- Scabiosa atropurpurea (pincushion flower)
- Senecio cineraria, also Centaurea cineraria (dusty miller)
- Tagetes spp. (marigold) – triploids are best for high temperatures
- Tithonia rotundifolia (Mexican sunflower)
- Verbena x hybrida (garden verbena)
- Zinnia elegans (zinnia)
The following annuals are not as heat tolerant as those above:
- Arctotis stoechadifolia ‘grandis’ (African daisy)
- Gazania rigens (gazania)
- Limonium spp. (sea lavender)
- Lobularia maritima (sweet alyssum)
Drought Tolerant