What To Plant In May

Planting can still be done during the month of May. However, it is crucial that newly planted plants are monitored carefully. Follow the watering schedule for newly planted plants in the watering section.
When planting native and desert-adapted plants, it is usually unnecessary to back-fill with soil amendments and vitamins or to add rooting hormones. However, a slow-release fertilizer high in nitrogen and phosphorous can be added to the backfill, if needed. 
Many cacti can be started from seed at this time.  Seed can be soaked overnight in water to help start the germination process. Place seed in a well-draining soil mix (½ quality potting soil and ½ perlite or pumice) and lightly cover with potting mix or gently press the seed into the soil. Keep soil moist until germination occurs.
SOW SEED OF WARM-SEASON HERBACEOUS PERENNIALS INCLUDING:
• Mexican Hat (Ratibida columnifera)
• Red Sage (Salvia coccinea)
• Desert Senna (Senna covesii)
• Sacred Datura (Datura wrightii)
• Mealy-cup Sage (Salvia farinacea)
VEGETABLES TO TRANSPLANT INCLUDE:
• Jerusalem artichoke
• sweet potato
• watermelon
• tomatillo
• jicama
• eggplant and pepper (by mid-month)
VEGETABLE SEEDS TO SOW INCLUDE: 
• Black-eyed peas (early part of May)
• cantaloupe
• okra
• tepary beans
• muskmelon
• tomatillo
• yardlong bean
• pumpkin
• summer and winter squash
• watermelon
Try the variety of melons from Native Seeds/SEARCH.
HERBS TO TRANSPLANT INCLUDE:
• basil
• Mexican-oregano (Lippia graveolens)
• Mexican-tarragon (Tagetes lucida)
• Cuban-oregano
HERBS SEEDS TO SOW INCLUDE:  
• amaranth
PLANT WARM-SEASON CACTI & SUCCULENTS INCLUDING: 
• Saguaro (Carnegiea gigantea)
• Prickly-pears (Opuntia spp.)
• Chollas (Cylindropuntia spp.)
• Barrel cacti (Ferocactus spp.)
• Hedgehogs (Echinocereus spp.)
• Pincushions (Mammillaria spp.)
• Easter Lilies (Echinopsis spp.),
• Paper-spine Cholla (Tephrocactus articulatus var. papyracanthus)
• Agaves (Agave spp.)
• Aloes (Aloe spp.)
• Candelilla (Euphorbia antisyphilitica)
• Desert Spoon (Dasylirion wheeleri)
• Giant Hesperaloe (Hesperaloe funifera)
• Slipper Plant (Pedilanthus macrocarpus)
• Elephant Food (Portulacaria afra)
• Burseras, Elephant Trees (Bursera spp.)
• Madagascar-palm (Pachypodium lamerei)
• Madagascar-ocotillo (Alluaudia procera)
• Dyckia spp.
• Carrion Flowers (Stapelia spp.)
• Texas-tuberose (Manfreda maculosa)
• Limberbushes (Jatropha spp.)
• Red-yucca (Hesperaloe parviflora)
Most Yuccas (Yucca spp.) can be planted with the exception of Joshua Trees (Yucca brevifolia).
When transplanting cacti and succulents, mark either the south or west side and plant facing the orientation you marked to avoid the burning of tender tissues. Most nurseries will mark the side of the container to help you determine proper planting orientation. However, if the original orientation is not known, newly planted cacti and succulents need to be covered with shade cloth if the plant surface appears to yellow or pale suddenly. Use a shade cloth rated between 30-60% as anything higher will block most of the sunlight and will not be suitable for your cacti and succulents. You may need to keep the shade cloth on the plant for the duration of the summer.
PLANT NATIVE AND DESERT-ADAPTED TREES INCLUDING: 
• Ironwood (Olneya tesota)
• Blue Palo Verde (Parkinsonia florida)
• Little-leaf Palo Verde (Parkinsonia microphylla)
• Mesquites (Prosopis spp.)
• Golden Leadball Tree (Leucaena retusa)
• Desert-willow (Chilopsis linearis)
• Palo Blanco (Mariosousa willardiana syn. Acacia willardiana)
• Catclaw Acacia (Senegalia greggii syn. Acacia greggii)
• Canyon Hackberry (Celtis laevigata var. reticulata syn. Celtis reticulata)
• Texas-ebony (Ebenopsis ebano)
• Twisted Acacia (Vachellia bravoensis syn. Acacia schaffneri)
• Feather Tree (Lysiloma watsonii)
• Anacacho Orchid-tree (Bauhinia lunarioides)
• Vitex (Vitex agnus-castus)
• Baby Bonnets (Coursetia glandulosa)
PLANT WARM-SEASON SHRUBS INCLUDING: 
• Yellow Bells (Tecoma spp.)
• Texas-sages (Leucophyllum spp.)
• Creosote (Larrea tridentata)
• Superstition Mallow (Abutilon palmeri)
• San Marcos Hibiscus (Gossypium harknessii)
• Desert Cotton (Gossypium thurberi)
• Guayacán (Guaiacum coulteri)
• Sennas (Senna spp.)
• Velvet-pod Mimosa (Mimosa dysocarpa)
• Ocotillo (Fouquieria splendens)
• Fire Bush (Hamelia patens)
• Ruellia (Ruellia peninsularis)
• Lantana (Lantana camara)
• Mexican Bush Sage (Salvia leucantha)
• Silver Nightshade (Solanum hindsianum)
• Little-leaf Cordia (Cordia parvifolia)
• Showy Mendora (Menodora longiflora)
• Sky Flower (Duranta erecta)
• Bird of Paradise species (Caesalpinia spp.)
PLANT WARM-SEASON HERBACEOUS PERENNIALS AND GROUNDCOVERS INCLUDING:
• Sacred Datura (Datura wrightii)
• Desert Four O’Clock (Mirabilis multiflora)
• Arizona Foldwing (Dicliptera resupinata)
• Buffalo Gourd (Cucurbita foetidissima)
• Mealy-cup Sage (Salvia farinacea)
• Yerba Mansa (Anemopsis californica)
• Rose-mallow (Hibiscus coulteri)
• Wine Cups (Callirhoe involucrata)
• Hummingbird Trumpet (Epilobium canum ssp. latifolium)
• Chocolate Flower (Berlandiera lyrata)
• Desert Senna (Senna covesii)
• Trailing Lantana (Lantana montevidensis)
• White Plumbago (Plumbago scandens)
• Mist Flower (Conoclinium dissectum)
• Rain-lilies (Zephyranthes spp.)
MANY VINES CAN ALSO BE PLANTED AT THIS TIME INCLUDING:
• Yuca (Merremia aurea)
• Queen’s Wreath (Antigonon leptopus)
• Yellow Orchid-vine (Callaeum macropterum)
• Passionflowers (Passiflora spp.)
• Arizona Canyon Grape (Vitis arizonica)
• Old Man’s Beard (Clematis drummondii)

Watering Your Southwest Garden In May

As the weather warms, plant water needs will increase. Now is the time to adjust your watering schedule for the summer. Observe plants regularly for signs of water stress. Some signs to look for include:  wilting, curling leaves, yellowing or falling of older leaves, and dead stems or branches.
The amount of water and watering frequency depends on many factors. These include soil type, weather (temperature, humidity, rainfall, etc.), microclimates, cultural practices, plant size and species, and whether newly planted or established in the landscape (two years or more). Below are general guidelines to help you determine how much and how often to water your landscape and container plantings to keep them healthy when rainfall is lacking.
Established native or desert-adapted trees and shrubs should be watered at least once to twice monthly. Water at least 3 feet deep for your trees and 2 feet deep for your shrubs. Always allow the soil to dry out between each irrigation cycle.
Natural rainfall may be adequate for most well-established cacti and succulents. However, if rainfall is insufficient, water may be needed at least once to twice during the month of May. Water your cacti and succulents to a depth of at least 8-12 inches. Always allow the soil to dry out between each irrigation cycle.
Established herbaceous perennials, groundcovers, and vines should be watered every two to three weeks and at least 1 foot deep. Always allow the soil to dry out between each irrigation cycle.
Wait a week after planting your cacti and succulents before watering to minimize the chance of rot. After the initial irrigation of your succulents, allow the soil to dry out and water every 10-14 days. Cacti need to be watered once more after initial watering during the month but allow the soil to dry out between watering.
Newly planted native and desert-adapted trees and shrubs may need to be watered more frequently until established. It can take up to 3-5 years for trees and at least 1-2 years for shrubs to become established in the landscape.  After planting your trees and shrubs, they should be watered immediately and the moisture monitored for the next few days to keep the root ball from drying out. Schedule your irrigation cycle for trees and shrubs every 7-10 days during the month. Allow the soil to dry out between irrigations and always water deeply, 3 feet for trees and 2 feet for shrubs.
Newly planted native and desert-adapted herbaceous perennials, groundcovers and vines should also be watered immediately and for the next few days to keep the root ball from drying out. Schedule your irrigation cycle for herbaceous perennials, groundcovers, and vines for at least once to twice weekly and to a depth of 1 foot. Allow soil to dry out between watering.
Agaves and other succulents (Aloe spp., Pachypodium lamereiBeaucarnea recurvataPedilanthus macrocarpusEuphorbia spp., Gasteria spp.,Haworthia spp.) in containers should be watered at least once to twice this month. Cacti in containers should be watered at least once this month. However, cacti and succulents in small containers may need to be watered more often especially cacti and succulent seedlings.
Keep an eye on your warm-season annuals and herbaceous perennials in containers. Water them at least once to three times weekly.
Herbs may need to be watered every 3-5 days and vegetables need to be watered every 2-3 days. Water your herb and vegetable plants to at least a foot in depth.