There is a famous song that tells us, “Summertime and the livin’ is easy,” but for roses, summer can be a challenge.

Adequate water will make all the difference to their continued health and vigor. This is the time to check your irrigation system and watch it run to ensure that enough water is reaching your roses.

Rose leaves have tiny openings called stomata on the underside of leaves. Water evaporates through the stomata in a process called transpiration, which keeps the plant cool by releasing water. It also creates the “pull” that draws water from the roots up to the stems, leaves and other growing regions of the rose. When the roots cannot supply sufficient water to the plant, the stomata close to preserve water.

Water is indispensable for photosynthesis and is vital to transporting nutrients to the plant. When the stomata close, photosynthesis is decreased. The resulting inadequate production of sugars causes the plant to grow fewer and smaller rose blooms in summer. If there is a continued lack of water, the plant is stressed further and will not grow at all. It will also be more susceptible to pest attack and fungal disease.

The plant requires more water in the heat, so you must increase watering in the summer and ensure that your watering methods are efficient. Do not wait to see wilted leaves and blooms as a tipoff to water your plants.

Watering in the early morning allows the water to soak in before it evaporates. It also minimizes fungal diseases such as black spot, rust and botrytis.

Add time to your irrigation as the weather heats up, and add an extra day or two of irrigation per week in the hottest summer months. I don’t find rules that tell me how many inches of water to apply per week to be very helpful, because there are many variables that affect how much water our plants need. The amount and frequency of irrigation depends on the growing season, the outside temperature and also how well our soil retains water. Sandy soils drain rapidly, while clay soils absorb water more slowly but retain water much longer.

Deep water your roses so they develop a healthy, deep root system. This will help roses stay cooler and more hydrated in hot weather, a big advantage over roots that remain at the soil surface because of inadequate watering.

Hotter weather, Santa Ana winds and the longer days in summer increase water loss from transpiration. Apply more water when the soil feels dry at more than 2 inches deep, and don’t wait for visual clues such as wilting or drooping leaves and blooms. A useful and inexpensive tool is a soil moisture sensor meter, which provides a reading that lets you know when your plant needs to be watered.

Roses grown in containers should be watered deeply, rather than more often with quick bursts of shallow water. This is because our water is salty and our plants will otherwise be susceptible to leaf burn. On days when the temperature is over 90 degrees, you may find it necessary to water container roses daily. In hot inland areas, put pot rollers under your pots and move your container roses to some partial shade. Container roses in plastic pots can be placed into ceramic pots to protect them from extreme heat.

Drip irrigation or soaker hoses deliver water directly to the soil and the plants’ roots so there is no water loss. Overhead sprays are problematic, because they can lose up to 50 percent of water to evaporation. They are also not precise in delivering water to each plant, especially in garden beds where roses are grown with companion plants that may be blocking water intended for your roses.

Access to a hose is essential when Santa Ana winds blow. A quick blast of water will cool down and wash off dusty plants and help relieve dehydrated and drooping leaves. Do this at any time of day, provided there is sufficient time for the leaves to dry before nightfall, in order to prevent water-initiated fungal diseases.

When we add organic amendments and an annual 3-inch layer of a porous organic mulch to our soil, we provide our plants with nutrients, better aeration and drainage. We also promote deeper root development, a cooler root zone, better water retention and a reduction in evaporation.

The rosebush needs its leaves for the production of energy and also to provide shade for the canes and the base of the bush. For this reason, avoid cutting long stems when you deadhead your roses in the summer or when you cut blooms to bring inside. Also, be watchful and keep your leaves as disease- and pest-free as possible. Speckled foliage and fine webbing under the leaves are evidence of spider mite infestations, which often peak in hot, dry weather. Spray jets of water under the leaves every three days while they are present.

We can and should fertilize our roses less frequently and with more dilution in the summer months. High summer temperatures cause plants to draw up nutrients faster, which could result in leaf burn. Skip feeding your roses when the weather is very hot, and always ensure that your roses are well-watered both before and after fertilizing.

Help your roses this summer by keeping them refreshed and hydrated. Continued blooms will be your reward.

Perwich is a member of the San Diego Rose Society, a Consulting Rosarian and a Master Gardener with UC Cooperative Extension.

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