Almost all of your plants will be blooming when butterfly numbers surge in August.Food for caterpillars Having a food source for caterpillars is vital, too. To accommodate this early butterfly stage, include an ornamental fennel, the favorite food of eastern black swallowtails. About midsummer, look for tiny, yellow eggs on the plant. Check every couple of days, and you’ll see a green caterpillar with yellow and black stripes. These black swallowtail larvae may eat your fennel to the base. But in three weeks, lots of beautiful butterflies will reward your patience. Dill, fennel, carrot and parsley do well, too. Add these to your garden freely to encourage more caterpillars.Plant height, vigor Pay attention to plants’ height and vigor. Lantana camara ‘Miss Huff’ and the butterfly bush (Buddleia davidii ‘Black Knight’) may look small the day you plant them. But each can grow into a bush 4 feet wide. Planted too close to other plants, these “towers with flowers” can crowd out and even kill them. Take note of each plant selection’s dimensions. Space them accordingly. 1996 Gold Medal selection Petunia ‘Purple Wave’ will spread fast. But it’s OK to let it run, since it will die at the first frost. Examples of potentially troublesome, but wonderfully spreading, plants include Monarda, Physostegia, Lycoris, Helianthus Viola and Lysmachia. Examples of improved, noninvasive plants include Passiflora ‘Byron’s Beauty,’ a sterile, nonrunning Maypop with dark green leaves and huge, fragrant flowers. A great forage plant for frittilaries, it’s like a butterfly garden in a container. Here are some butterfly-attracting flowers (those with asterisks may be considered annuals in more northern climates):Annuals Tithonia rotundifolia, Salvia splendens, Phlox drummondii, Zinnia elegans, Impatiens capensis, Nasturtium glauca, Petunia x hybrida, Justica brandegeana, Nicotiana alata, Plumbago aurantiaca, Pentas lanceolata, Catharanthus roseus (Vinca), Bougainvillea spectabilis and Antirrhinum majus.Vines Aristolochia (most kinds)*, Passiflora (most kinds)*, Ipomoea quamoclit*, Lonicera japonica, Campsis radicans and Phaseolus coccineus*.Perennials Salvia coccinea*, Lantana camara*, Lavandula (most kinds), Liatris spicata , Nepeta gigantea*, Rudbeckia hirta, Echinacea purpurea, Sedum (most kinds), Verbena bonariensis*, Verbena tenuisecta*, Verbena canadensis*, Veronica spicata, Gaura lindheimeri, Asclepias tuberosa, Amsonia tabernaemontana, Aster novi-belgi, Salvia (most kinds)*, Phlox paniculata, Centranthus ruber*, Kniphofia uvaria, Lobelia cardinalis, Monarda didyma, Penstemon barbatus, Boltonia asteroides, Passiflora (perennial sp.)*, Solidago (most kinds).Woody Ornamentals Abelia grandiflora, Aesculus pavia, Weigela florida, Lonicera sempervirens, Azalea (most kinds), Rhododendron (most), Buddleia davidii, Caryopteris x clandonensis and Viburnum (most kinds).Herbs, Vegetables and Fruits Anethum graveolens, Foeniculum vulgare, Daucus carota, Petroselinum crispum, Pimpinella anisum, Ruta graveolens and Citrus sinensis. For a successful butterfly garden, it’s vital to select nectar-producing plants with accessible flowers. Even in hot weather, when many flowers aren’t in bloom, butterflies still need nectar.Lantana and purple coneflower (Echinaceae purpurea) produce nectar and attract butterflies continuously, even in the hottest droughts.Butterfly gardeners need to look at annuals and perennials in a different light. It may mean a trip to the library or World Wide Web to learn more about bloom time, nectar and forage characteristics.Bloom Time Provide plants that will bloom in sequence, providing nectar from March 1 to the first killing frost. Georgia has two butterfly broods, or flushes: one in early spring and another in midsummer. It’s essential to have nectar then. Verbena ‘Homestead Purple’ will flush in early spring through early summer, then “rest” and flower again in late fall. This provides nectar for early- and late-season butterflies such as question mark, red admiral and zebra and tiger swallowtails. Plants such as blue anise sage (Salvia guaranitica) and purple coneflower will flush in cycles if you pick off the spent flowers. Verbena bonariensis will stop flowering. But you can cut it halfway back in early August to stimulate new flowers.