Also serving the communities of De Luz, Rainbow, Camp Pendleton, Pala and Pauma

Protect roses from heat damage

All projections I have read indicate that we may be entering another period of

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. I will discuss three strategies here.

1. Deliver 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.

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 i'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 netafimusa.com.

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.

2. Mulch

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 an 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.

3. 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 and be sure to water them deeply.

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! (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.

As areas open up for socializing and we can venture out, The San Diego Rose

Society has quickly arranged to have a Rose Show June 12. Entrance is free and

anyone can and is encouraged to enter. More information located here:

https://www.sandiegorosesociety.com/rose-show-auction.

Doesn't look like much work, right? Well, since you'll be taking it easy during the summer, go visit Rose Haven, located at 30592 Jedediah Smith Road in Temecula. Also, visit www.TemeculaValleyRoseSociety.org.

 

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