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How to efficiently water roses in a drought and get them through summer heat

Frank Brines

ARS Master Rosarian

It has been confirmed that California is now in yet another drought. As gardeners we must be watchful and learn how to efficiently manage the amount of water we apply in our gardens. With summer and the warmer temperatures to come, this will help diminish heat damage (stress) to the plants.

The strategies I will discuss here are delivering water efficiently, keeping water in the soil using mulch, allowing your roses a summer dormancy period.

Delivering water efficiently

Installing the most efficient delivery system is one method to save (conserve) water. Learning your garden's soil type will help you make a decision on which systems work best and how much water to deliver at any one time. (Growing in pots is another story!)

Typical mature, full-size hybrid teas in Southern California require about 6-9 gallons of water a week in moderate temperatures (e.g. 70s). As temperatures rise into the 80s, they require about 9 gallons per week. In the 90s, about 12+ gallons. A rose can stay alive on considerably less, but they may come through the experience debilitated.

Drip systems are the most efficient way to deliver water because they don't produce a spray that can be carried away by the breeze and deliver water slowly so it soaks deep rather than running off. If you have a drip system, be sure it's in good shape before you go on to the next step and cover it with mulch! Open each irrigation valve one at a time and repair leaks.

I like Netafim products for their integrated pressure-regulating emitters. Find the information at

Lastly, estimate how long to run each system. Multiply the number of emitters by their delivery rate (e.g., 1 gallon/hour), then divide by the number of roses. For example: if you have 40 emitters, each delivering 1 gal/hr., you deliver 40 gallons per hour. If you have 10 roses, that's 4 gallons per rose. To deliver 12 gallons per week, run for one hour three times a week.

This should work well in a typical loam soil. You want the water to soak down at least 12" for optimal rose health. A loam soil doesn't allow water to just run through it, so irrigating for an hour at a time can be fairly efficient. On the other hand, if your soil is particularly sandy (water permeates more quickly) an hour may waste water, so run the system twice as often for half as long.


If you have read my past columns, you know that I advocate a 3"-4" layer of mulch. Mulch moderates the soil temperatures, retains moisture and allows it to spread throughout the root zone, discourages weeds, and enriches with nutrients and biomass. There are many materials you can use, but I recommend composted mulch.

You might experiment with a variety of material, but you'll probably get the best results if you don't mix them in any one garden bed. For example, some gardeners have access to pine needles. They provide a cool airy barrier and break down very slowly to impart a more acidic soil environment which makes mineral nutrients more available to plants.

Another material is any size of wood chip specifically intended as mulch; I recommend the finer cut forms. Possible drawbacks: If not specifically manufactured for garden use, there is the potential for matting due to fungal growth, which can make the mulch impermeable to water – and the need to apply added nitrogen to break down the wood fibers. I'm not an advocate for dyed wood products.

Whatever material you choose, be careful to not apply it up to or over the bud union. Leave a clear area around the base of the plant of about 12" diameter. (If you can maintain that distance, then as your composted mulch disintegrates it will not raise the soil level around the bud unions.) This open area is one way the bush gets oxygen to the root area. Also, keep foliage pruned to at least 8" above the mulch layer to reduce infestations from pests like spider mites.

Summer dormancy

Allowing your roses to go dormant during the hot summer months will reduce the stress on your plants. You won't be missing out much because when you allow roses to power through the summer, most blooms are poor quality with burned petals and leaves.

To encourage this dormancy, stop feeding established roses near the end of June but be sure to water them deeply. For your June fertilizing program, I suggest using a product with higher phosphate (the middle number of products uses the three N P K system) as it helps plants cope with the heat and high temperatures.

As blossoms fade, remove only the petals – do not deadhead them – that is, allow hips to form. This discourages new growth and flower formation, thus reducing demand for water. Remove fallen leaves and discard them along with the petals into your green yard waste bin – do not compost them unless you know for certain that your compost pile reaches a sufficient temperature to kill pathogens! (It is always a good practice to keep the garden clean in order to reduce fungal diseases and insect pests, particularly in hot dry weather.)

Do not remove sunburned leaves because they provide shade for the cane which can be damaged or killed by sunburn!

In summary, until at least September:

· Do not feed

· Make sure your water delivery system is operating efficiently

· Apply 4" of mulch over the entire bed

· Remove petals as flowers mature

· Do not prune or cut back: Allow hips to form

· Leave burned leaves on the plant

Potted plants will require more diligent watching, resources and attention to what they are experiencing during this period. Learn to listen to your plants and observe their reaction to the elements.

Doesn't look like much work, right? Well, since you'll be taking it easy for the summer, go visit Rose Haven, located at 30592 Jedediah Smith Road (the cross street is Cabrillo Avenue) in Temecula. Also, visit the web site,


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