The Tucson Botanical Garden very abundant and healthy vegetable garden after a long hot summer. 

Keep soil covered with plants and mulch to prevent water evaporating from the soil.

Plants struggle when there’s not enough water to keep them from functioning properly. It’s difficult to keep them happy with water restrictions, and thirsty plants are much more susceptible to insects and diseases. Water is a precious resource and we have to make the most of what we have, so that means we have to garden in a more sustainable manner.
 
Here’s a few tips to keep plants healthy while preserving our precious resource:

1. Add Organic Matter: Compost, leaf mold, well-rotted, composted manure and other organic matter to the soil and mix it in a couple of inches. Organic matter acts like a sponge keeping soil wetter for longer. It also opens up clay soil and bulks up sandy soil. Compost is a good thing – a very good thing indeed.
2. Add Mulch: Any moisture in the soil quickly evaporates when the soil is left bare. Either cover the soil with plants, including groundcovers, or add nature's blanket. Add a 3 inch layer of an organic mulch on top of the soil between plants. Soak the soil (and weed) and water plants before placing the mulch. It has to be 3 inches deep in order for it to be effective. The mulch holds in soil moisture so it doesn’t evaporate and as an added bonus it deters weeds. Don’t put fabric under the mulch as it defeats its purpose.
3. Avoid Rock Mulches: Rocks reduce evaporation slightly, but they are not as efficient and beneficial as an organic mulch. Rocks don’t insulate the soil either, like rock mulch. They stay hot in the summer and cold in the winter.  

Adding organics such as leaf mould and compost acts like a sponge to absorb moisture.

Fall leaves make a great free mulch.

1. ​Water Properly: Water plants thoroughly. Long deep soaks once a week results in long roots that survive environmental stresses such as heat and drought. A little bit of water causes more harm than good as it promotes shallow roots, which succumb to the trials and tribulations of temperature extremes. Since dry soil sucks away any available moisture, water the plants and the soil between the plants. This keeps the ground wetter for longer.
2. When to Water: Water early in the morning not at night. You can water later in the day, but do it so they are dry by nightfall.​ Try not to plant new plants including lawns during the summer. It is just too difficult to maintain soil moisture for plants to successfully become established into their new home. Autumn is the best time to plant as it’s rainy, the soil is warm and the air is cool. The other best time to plant and transplant is early spring. Wait until the ground no longer drips water when squeezed.​

Wilting geranium (Pelargonium) leaves.

Wilting plants? Use a trowel or shovel to see if the ground is moist. Maybe you are not watering enough. Most sprinklers should be left on for 30 minutes minimum. Plants also wilt if the soil is saturated, so do dig down and check to make sure there is adequate drainage
Provide Shade​ The hottest sun of the day occurs in the afternoon from the south and west exposures. Plant large shrubs, trees or a screen on the west and/or south side of gardens that are frying in the heat of the day. For a temporary solution prop up a tarp, sheet or umbrella to block the light if plants are wilting in the afternoon. It would  be a good idea to consider moving ones that are perpetually wilting to a shadier location in the autumn. 

Shrubs and trees on the west and south side provide shade for the more sun sensitive plants.

If plants are wilting, despite having adequate water, set up a temporary screen with some burlap to protect plants from the scorching sun.

Timing: The best time to plant is fall and early spring, this includes lawns too. It’s just too hot and dry in the summer.   
When: Early morning is best, followed by late in the day but before it gets dark. Avoid watering when it’s windy and in the heat of the day.

Soaker hose seep water along their length.

Space hoses and drip systems close together.

Drip and Soaker Hoses: Drip systems are excellent for planters, but not ideal for gardens. They only wet a very small area so they must be placed strategically next to the plant. Check to see the pattern of wetness and adjust the time so the It does nothing to help the soil ecology so a good 3 inches of mulch is essential to preserve any soil moisture.  Soaker hoses seep moisture into the soil, but as with drip systems the moisture doesn’t spread far and wide. Place the hoses close together for more effective wetting.
 
Collect Water: Rainbarrels are a great idea, especially when rain water is directed from the house gutters to a downspout. Instead of water going down the drains, collect water in a bucket while you shower. Use the dirty dishwater by washing the dishes in a tub in the sink, then toss it onto the garden. ​​

Hand watering plants is essential when first planting and if plants are wilting.

A drip system only emits water at one small spot and isn't beneficial to soil ecology.

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Drought Tolerant Plants

Drought Tolerant Plants & Planting: There are many plants that are suitable for dry soil. As soon as you plant them, water them by hand then water every 2 to 3 days so their roots become established into the surrounding soil. Just because they are drought tolerant doesn’t mean they don't need water. As soon as the plant develops new leaves, you know their roots have grown into the soil. Ease up on the water once and water accordingly. Drought tolerant plants still need moisture to survive, so do provide water every two weeks or monthly depending on the needs of the plant.

Annual: African Daisy, Osteospermum

Elijah Blue blue fescue and a Tam juniper.

A perennial ground cover called Basket-of-gold, Aurinia saxatilis.

Annuals:  African daisy (Osteospermum), portulaca, cleome, cosmos, marigolds, scarlet sage, sunfowers, verbena, ageratum, Madagascar periwinkle (Catharanthus roseus), zinnia, blanket flower (Gaillarda), verbena
Ornamental grasses: blue fescue, calamagrostis, miscanthus
Perennial flowers: purple cone flowers (Echinacea), bearded tongue (Penstemon), black eyed susans (Rudbeckia) , blazing stars (Liatris), butterfly weed (Asclepias tuberosa), daylilies, lantana, yarrow (Achillea millefolium), basket-of-gold alyssum (Aurinia saxatilis), snow-on-the-mountain (Cerastium tomentosum) false indigo (Baptisia), catmint (Nepeta), bidens, red-hot poker (Kniphofia), wormwood (Artemesia)
Shrubs: purple smokebush (Cotinus coggygria 'Royal Purple'), tamarisk, Beautybush (Kolkwitzia amabilis), ninebark (Physocarpus opulifolius), burning bush (Euonymus alatus 'Compactus'), Caryopteris (Bluebeard), butterfly bush (Buddleia)
Herbs: Lavender, thyme,sage, Russian sage (Perovskia)
Succulents: hens and chicks, stonecrops, sedums and sempervivum, yuccas, agave
Vines: honesuckle (Lonicera), bougainvillea
Trees: Honeylocust (Gleditsia triacanthos), weeping peashrub (Caragana arborescens ‘Pendula’), Turkish hazel (Corylus colurna), Russian olive, five-leaf aralia, sea buckthorn
Evergreens: Junipers, pines

A perennial, torch lily also known as red hot poker, Kniphofia uvaria.

Ageratum, a purple annual, and black-eyed-Susans, a yellow daisy-like perennial.

A honey locust tree called Gleditsia triacanthos.

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Don't let these Plants Dry out!

Make sure the following plants don't dry out as they need regular watering to be strong and healthy. 

1. Azaleas and rhododendrons (Rhododendron species),
2. ash (Fraxinus species)
3. astilbes (June 2017 Plant of the Month)
4. mountain ash (Sorbus aucuparia)
5. birches (Betula species)
6. hydrangeas 
7. tulip tree (Liriodendron tulipifera)
8. Skimmias 
9. Stewartia pseudocamellia  
10. sweet gum (Liquidambar styraciflua)
11. ornamental flowering cherries, plums (Prunus species)
12. dogwoods (Cornus species)
13. maples (Acer species)
14. horse chestnut (Aesculus hippocastanum​)

Ornamental Japanese flowering cherries, like this Shirofugen will be healthier if give water during the summer.

Lungwort (Pulmonaria) needs moist soil.

Horse chestnut (Aesculus hippocastanum) is a large tree that needs water or it will wilt like this example.

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How to tell when plants are Thirsty

Common symptoms include:

• leaves curl or roll inwards
• limp, wilted, droopy  leaves
• small leaves
• yellow leaves
• slow growth
• flowers, fruit and leaves drop off the plant
• leaves are brown at the edges
• branch ends die, which eventually extends to the entire limb
• premature leaf colouring in autumn

Snow-on-the-mountain (Cerastium tomentosum) holds onto morning dew.

A weeping grafted willow with small leaves with dried leaf margins, which indicate it is a victim of drought.

The leaves of this astilbe have curled inwards in response to a lack of water.

Lack of water has caused this oakleaf hydrangea leaves to turn brown at the edges.

Corn is tolerant to dry soil, however, this crop is dying for a drink.

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