Roses in a Desert Garden: An Overview From the First Summer

I decided I really should give some thought to Kris's suggestion of a post about this year's rose-growing experience.  While I have no idea how they will fare next year and the year after that, we (the roses and I) have survived our first summer in the desert garden and all are alive and most are well.  And I have certainly learned a few things!  So here are my notes...

Selection

 Roses grow successfully in a surprisingly wide range of environments, and the desert is by no means the toughest for them.  The dry air discourages many of the diseases that make life difficult for rose and gardener in more traditional growing areas.  Water is necessary, of course; but I feel that, overall, roses are roughly as drought-tolerant as all but the truly desert-adapted plants I am growing.  I don't know whether that will hold true in the long term, but it certainly has been true during this summer.

I've been particularly pleased with the big shrub roses, which in this case means David Austin varieties.  I don't know whether it's true or not, but my instinct is that - with a root structure to match their size - they are actually better suited to a low-water environment than a smaller hybrid tea or floribunda.  Those roots have more room to spread to get to available moisture.  Right or wrong?  I don't know...  The more recent D A roses have been selected for vigour in any case, and apparently quite successfully.  I did refer frequently to their lists for hot climate growing (this list appears to be only in their US print catalogue) though I certainly did not follow it to the letter.

An additional point is that most of these were own-root bushes.  Again, I have no way of knowing whether this has contributed to their vigour, but it certainly hasn't hurt!

Siting

Probably the single biggest factor is shade.  Shade in the desert garden is not so much a problem as a boon, mitigating the intensity of the sunlight and blocking some of the drying winds.  Wollerton Old Hall, directly shaded by the porch roof for much of the day, has grown largest by far and bloomed more heavily than any but Crown Princess Margareta.  In the Rose Border itself, the three roses that receive some shade from each side (two palm trees are incorporated into the border) have been much happier than the two that only receive the shade from one side.  Another big factor to consider is protection from drying winds.  Rose foliage is often fairly leathery, but it is not really made for the strong, hot winds that can desiccate even better adapted species.  A windbreak is highly desirable.

Water

While roses are not desert natives, their water requirements are surprisingly moderate.  During this summer the plants were settling in so I tried to take no chances with the water.  While temperatures were at their hottest (and driest) - which meant daytime highs above 109 F (43 C) - I watered every day.  With temps in the low one hundreds or nineties (32 - 40 C), I've been able to move to a three or four day schedule.  These bushes are in their first year in this garden, and I don't know what next summer will bring in terms of water needs.

Another factor is the watering method.  I have used a slow hose to supply a deep soak as plants are still small and too widely spaced for a soaker hose to be efficient.  Using this method, a soil basin around each rose is, of course, standard practice in order to hold more water that can soak in over a longer period.  On two of my bushes the basins were made a little smaller because the original plants were smaller.  This was unfortunate as they received less water overall, and it was probably a contributing factor in their slower growth.  The soil in the Rose Border is more clay than sand and it is hard to redig a basin so I didn't properly correct this.  Eventually mulch proved to be the best solution.

Mulch

As I've written elsewhere, I decided to try a sawdust mulch derived from pelleted pine bedding.  This material is capable of absorbing a great deal of water, conserving it for slow release at the base of the plant.  It also keeps the soil much cooler than a rock mulch or even standard bark mulch.  It would, perhaps, contribute to rot in any cooler, moister environment, but I have seen no signs of trouble here, despite using it on a number of  "never mulch" plants, including lavender and artemisia.  I have given a bit of extra nitrogen to avoid chlorosis as the mulch breaks down, which it has done nicely, leaving a crumbly compost of sorts on the soil surface.  The roses have certainly responded well, and it was after a thorough mulching that the two slow-starters began showing signs of more rapid growth.  Circumstantial evidence, I admit...  At all events, I think that a well-applied mulch will save much stress on both rose bush and gardener.

Feeding

I have to assume that our soil is not very nutritious.  In the vortex of getting the garden established, I have simply used liquid plant food (Miracle Gro to be specific), adjusting amounts as I deemed appropriate to the various plants.  (This means small-to-negligible doses for desert natives that don't want much nitrogen.)  I've kept to a two week cycle until recently.  So the roses have been fed the full recommended amount every two weeks through the summer.  They were also planted with a good helping of aged manure in the planting holes.

Pruning

I confess to being somewhat compulsive when it comes to pruning roses.  I enjoy snipping away, gauging which group of five leaflets to cut to.  But while this is necessary to encourage good repeat bloom in the old hybrid teas and floribundas, it is not considered vital for shrub roses.  The David Austin catalogue, however, does recommend it (referred to as "summer pruning") for certain varieties grown in hot climates, with the explanation that they may otherwise put their energy into cane and foliage growth rather than flowers.  With a little judicious pruning, this green-at-the-expense-of-flower can supposedly be avoided.  Having said which, some of my roses have only increased in size over the summer, rather than putting out much bloom.  Which brings me to another important point...

Expectations

June is, after all, the classic month of roses.  But June in this garden is one of the most brutal months of the year, bone dry, with high temperatures rising to at least 114 F (46 C) from time to time and remaining above 110 F (43 C) for extended periods.  Even though rains will (hopefully) begin in July, temperatures are still high and plants are struggling to recover from May and June anyway.  (Last May was unusually mild.)

It is for this reason that I have not added any once-blooming roses so far, despite having some dear favorites in this category.   Perhaps they would bloom just before the worst of the weather, but I fear there would be a race each year between roses and summer heat.  The repeat bloomers, on the other hand, can afford to wait, and sulk while temperatures go sky high, and send up the occasional bloom to scout conditions.  There is always autumn ahead, and a repeat-bloomer can make the most of it.

So I've focused on planting roses with a reputation for good repeating, and I was actually happy that most of the bushes waited the summer out just in the green, though I was very impressed by the ones

Graham Thomas in a desert summer; the bees were still happy!

who went ahead and bloomed heartily!  Also, I wasn't too upset when blooms were the "wrong colour" or the wrong size or shape, which means very small and/or few petaled.  This I consider to be the roses' way of dealing with the stress of a very hard summer.  If they want to go ahead and bloom, I'll not complain too much about the quality of the blooms.  I, too, am waiting for autumn, when the colours come right again and the roses can relax and put out their best.  With our mild winters there is the chance of nearly year-round bloom here, which compensates for a great deal of summer.

Rose by Rose

Wollerton Old Hall has grown very well and would like to climb.  It receives more shade than any other rose in the garden and has responded enthusiastically.  Blooms have remained sparsely petaled through the summer, but to make up for this the bush has bloomed robustly throughout.  It is said to be quite fragrant, but I have found it only mildly scented during the hot months, at any rate.  It is quite a charming rose, with colour ranging from cream to primrose yellow.

The Alnwick Rose, though listed for hot, dry climates, has not been over-vigorous.  This, however, is almost certainly due to an attack of spider mites as the bush was settling in - an attack from which it has struggled to recover.  It finally has a couple of buds coming along...  Foliage still shows some signs of stunting.  I certainly hope it will pull out of its hard start as this is an exquisite variety at its best, full of soft pink petals, full of rich fragrance.

James Galway is one of the slow-starters in the Rose Border.  Not listed for hot climates, but I think that he is actually coming along well now that I have taken care of the watering problems.  Foliage and canes are quite lush, and a flower finally opened yesterday. 

Graham Thomas is next.  I have not known what to expect as I found this variety a bit tender in the Midwest, whereas my cousin in mild San Diego is growing the classic Graham Thomas, California-style - somewhere around 8 to 10 feet tall with no support, an enormously happy shrub!  The verdict is still out on desert growing because this was the other bush receiving a bit less water than it needed as it settled.  However, I feel that this is the one variety I would not necessarily recommend for inland desert growing; it appears a little more bothered by the dry conditions, wilting just a little quicker than any of the others.  The problem may disappear as it grows, and I certainly hope it does because this is one of the classics and well deserves its reputation as "world's favorite rose".  I must say that it did try to continue blooming through the heat, but it seemed to have a knack for trying at the worst times.  Hopefully it will soon come into sync with its location.  In any milder summer climate, or perhaps in a more humid one, Graham Thomas is a rose not to be missed!

The Generous Gardener is to my eye possibly to most beautiful of the roses that have bloomed here so far - this despite never yet blooming in its "normal" pale pink.  All flowers to date have been more or less white.  However, the form, slightly reminiscent of a water lily, is there: wide open with a plenitude of delicate petals (my picture does not do it justice).  And the scent is marvelous.  It has not bloomed heavily, sending out only the occasional tantalizing blossom through summer. It bids fair to be the tallest in the Rose Border as its canes are more vertical than the others.  In future I intend to try a more rigorous pruning schedule on this one as I definitely want more of those blooms!

Crown Princess Margareta is undoubtedly the best performing variety so far.  It is only listed in the catalogue as good for hot, humid climates - a great oversight, judging by this summer's growth and bloom!  Flowers for much of the summer were cream to soft pink; they are now in their regular apricot hues.  As temperatures spiked, flowers became quite small, almost miniature - and went on blooming.  This variety recovered quite quickly as summer closed.  I really cannot say enough good things about Crown Princess Margareta: beautiful, robust, very free-flowering.  My only concern has been that readers of this blog would become bored because I presented her so often...!    By no means up to her anticipated 5 ft yet, she has spread horizontally to meet her neighbors already.

St. Swithun is a large bush with beautifully big flowers, which are a soft powder pink with a lovely flat form when fully open.  Fragrance has been a little lighter than I hoped though certainly present.  The bush itself has been very robust, spreading in all directions.  This has been another variety that successfully attempted to bloom through the summer, though usually only one or two flowers at any time.  But it seems particularly well-adapted here.

William Shakespeare 2000 is probably my top favorite in the way of red roses.  I had dreamed of growing such a luscious red rose in the planter in our front patio, and I suited the action to the dream, only to find that that is a nearly impossible place to grow anything.  Spider mites struck and, finding it difficult to recover from the mites while roasting in the summer heat that is reflected very intensely from the surrounding walls, the rose has made little growth.  For all this, it is alive and has tried to bloom a few times; my intention is to shift it to the garden, where it may possibly regroup and fill out and bloom.  I do note that William Shakespeare 2000 is the one rose grown on rootstock rather than its own roots.  Honestly, though, I don't consider its weakness to be due to anything but nearly impossible growing conditions and a bad bout of spider mites.  Even though the blooms were never up to standards, the fragrance, which is part of the splendour of this rose, was there in full.

For this picture I am cheating, as I took it in my cousin's California garden, where it was among my favorite roses

Sterling Silver is the only hybrid tea rose that I have growing in the ground.  Others have found their way into pots on the back patio, but I won't discuss them here, except to say that the results are not much different than in the garden proper.  Despite my greater confidence in the large shrub roses, Sterling Silver has performed very well.  As I've mentioned elsewhere, the variety has a reputation for starting slowly.  Here it has been fairly robust and quite free-flowering.  Blooms have been badly formed during most of the summer, but it is starting to come back now in early October.  At its best, the form is the classic old "Ophelia" shape, but in a pale lavender hue, and the fragrance is superb.  A bit of a dowager now, but with a great deal of beauty, and really - though there are other lavender roses out there - there is nothing else quite like her.

Daniela is the only miniature rose in the garden at present.  She has been such a success that I intend to add more when they become available.  This is another plant right under the protection of the patio roof, and it has grown sturdy and lush.  It has been generally free-flowering, with the exception of a break during high summer.  It is now once more loaded with flowers, but - as with some of its larger relatives - they are not fully double; in fact, at present most are really single: little five petaled spots of red with white centers.  In full form it is a tiny replica of a hybrid tea bloom, with a tiny but abundant version of the fragrance.

Other Considerations

Pests have so far been very manageable with spider mites doing the greatest damage.  Other issues that have appeared have been from aphids and thrips.  There are grasshoppers, but so far they have not been numerous enough to do much harm and control has been limited to the occasionally successful stomp (one could hardly refer to this as "hand-picking"?).  So far this year we have not had any caterpillar invasions; last year was a banner year for sphinx moth caterpillars, and it gave me a good scare as I had just decided to begin this garden.  I never did see much damage from them either, though I don't doubt they could do quite a bit in a cultivated area.  Personally I am not adverse to using pesticides in an intelligent manner, but frankly it hasn't been necessary to date.  A strong spray from a garden hose works well for either mites or aphids, and it makes the plants a good deal happier too!  In midsummer, I like to do this job at dusk to avoid sunburnt foliage.

Back to the question of selection, from this summer's experience I would recommend using the very full-petaled varieties (petal count over 50 or even over 70) if you object to having single or semi-double blooms through the hot months.  Roses such as St. Swithun and Crown Princess Margareta seem to keep their high petal count and overall form while those with a lower count, such as Wollerton Old Hall, may drop to twelve petals, or thereabouts.  This is also true of the HTs, which are rarely over fifty petals.

As for sourcing roses, I ordered my David Austin roses directly from their website and would certainly say that the plant quality was very high.  Here in Arizona there is still apparently a good deal of rose growing for the trade, and I have found it fairly easy to purchase 3 or 5 gallon containers of the classic HTs and floribundas at very reasonable prices.  We now have a menagerie of favorites growing in pots in the back patio.  Though I rarely mention them, the list includes Tiffany, Olympiad, Tropicana (Super Star in the UK), and Sun Flare.  The patio garden is mostly under my sister's jurisdiction, but I should post about it more often since it has been a very enjoyable project with some wonderful plants.

But for now I am only discussing roses out in the open garden!  I hope this is of use to anyone looking at growing roses in these hot, dry areas.  It is mostly just an adaptation of standard rose-growing practices, but perhaps my notes on these adaptations will help and/or encourage anyone interested in trying it.

Weather Diary: Partly cloudy with patches of rain; High: 91 F (33 C)/Low: 69 F (21 C)