Thursday, September 4, 2014

Week Eleven

Daisy and I just wrapped up our last full day of the internship with Kew.  We did the daily 4:00 tool shuffle for the final time.  Then I stayed in the shed a bit later to clean and sharpen my secateurs for the next person.  I would do it tomorrow morning, but I wasn't sure if I'd have time.  However, we did too many interesting things this week to write a pensive, thoughtful, last week post.  I'll save the conclusion of this blog for when I get home to Tennessee.  Let me tell you about our week.

The Salvia Border is divided into two groups --
"old world" ad "new world" sages.  Those closest
in the photo are "new world" selections.
Daisy and I both took Monday off.  I was in Edinburgh until Monday night, and Daisy was preparing for the fall semester of her master's program.  I felt a tinge of regret to miss our last edging day (little did I know...), but it was nice to have a holiday outside of London for a bit.

Stunning Salvia
Tuesday morning, India had a special treat for us.  Daisy and I were going to assist with a Salvia propagation request.  We've done a fair bit of work in the salvia border this summer, and it seems fitting to write a bit more about this beautiful border as this week's topic.

A quick background
The salvia border runs along the western side of a brick wall that borders the order beds and the rock garden areas.  The border is divided in two by a path that connects these two areas.  The section that is closest to the School of Horticulture building contains "old world" salvia species.  These are sages that are native to Europe, Asia, and Africa.  The section nearest to the woodland garden has the "new world" salvia collection.  These are all native to North and South America.

Although the Salvia Border is only
about nine years old, the brick wall
behind it dates back to the 1700's
India tells me that the border was planted sometime around 2005.  Kew's salvia border is quite new when you consider how old the gardens are.  However, the brick wall that runs behind the border is actually very old.  It is the only remaining boundary wall that separated the historic Botanic Garden and Pleasure Grounds areas.  This section of the wall served as one part of the perimeter for the Royal Kitchen Garden.  The other sections of the boundary wall were demolished by then director Sir William Hooker in the 1800's (Desmond, 373).

Like any truly old structure, this wall has has been added to and patched up on occasion.  The attractive window-like design at the top was added in the 1870's.  The largest repair job was done in 1965 after a gale blew down a 60 foot section of it (Desmond, 373).

My regular readers may be familiar with some of the chores we do in the salvia border.  Most of what we've done this summer has been deadheading and watering.  I mentioned a few weeks ago that although many sages are extremely drought tolerant, the specimens at Kew have adapted to London's normally frequent rain showers.  The month long drought this summer stressed out many of the plants in this area.  Daisy and India watered with hoses and watering cans, but sometimes that still wasn't enough.  There were occasions when the drip irrigation had to be left on all day or overnight before the plants would perk up.

Most of the maintenance that I've done in with salvia is deadheading.  For anyone who doesn't know, deadheading is the process where the finished flower heads are cut back to encourage another flush of blooms.  Busy gardeners may just hack "new world" sages back to about a foot after they've finished flowering mid-summer.  The plants will recover in time for another show in the fall.

This summer we had enough staff available to properly deadhead.  About once a week a small group of us would spent some time carefully snipping back to spots on the stem that had new buds emerging.  Although this took a fair bit of time, the "fiddly" work paid off with virtually non-stop flowering.

Hobby gardeners and professionals alike relish the opportunity to grow plants from cuttings.  It's intensely rewarding to take a sprig of stem and encourage roots to sprout from the base.  You would think that with the size of Kew, many of the staff would have the chance to propagate plants pretty frequently.  The surprising truth is that Kew is so massive that they have an entire team whose only job is plant propagation.  When an area needs new plant material, they submit a "prop request" to the team and receive the plants when they're ready to go out.

Joanna demonstrates how to collect
Salvia cuttings to propagate
Joanna, a member of this propagation crew, showed Daisy, India and the ropes as she carried out India's prop request for the salvia border.  The first step was to go through some health and safety training for the chemicals and tools that we would be using.  This involved reading some paperwork and signing forms.  After that, we went out to the salvia border.

Joanna provided us with sterile secateurs to use rather than our own.  We also had to re-sterilize the pruners between accessions to prevent spreading disease through the collection.  Many of the salvia were infested with leafhoppers, so we also had to carefully remove any foliage that had leafhopper damage.  "We don't know where they've laid their eggs," Joanna told us, "But we know they were on the damaged foliage."  Leafhoppers can be extremely difficult to control once they become established in the propagation house, so Joanna and her crew do as much as they can to prevent them from getting in.

We transported the stem sections from the salvia border to the propagation area in moist plastic bags.  We added a bit of water to the bags, then shook them to spread the droplets around, then emptied what remained so there would be no standing water to soak the plants at the bottom of the bag.  We placed two labels, complete with scientific name and accession numbers, in each bag at the time of collection.  This helped to keep us from mixing up the specimens.  When we arrived to the propagation house, Joanna placed our collections in a refrigerator.  This prevented the plants from drying out while we were working.

This Salvia is just about
the right size for rooting
Joanna and I pushed a clean table out of the propagation house to a flat area nearby.  We worked outside of the propagation house to help keep any leafhoppers still on our material from escaping into the greenhouse.  We were given sterile knives and cutting boards and went to work.  We prepared a second moist bag and placed one of the labels in each bag.

First we cut the stems into sections that had four nodes.  The bottom-most node was cut flat, and the leaves and buds were carefully removed from the bottom two buds.  Joanna explained that roots were more likely to spring from the meristematic tissue present at the nodes.

Next we removed excess foliage.  If you remember from your science classes in school, leaves photosynthesize, and water is required for photosynthesis.  Water is absorbed from the roots, but cuttings don't have any roots.  Removing some foliage or cutting large leaves in half reduces the amount of water needed by the stem, which improves the chances of developing roots successfully.

When we had prepared enough cuttings, we soaked them for a short period in a diluted ammonia mixture. This would suffocate any remaining pests and sterilize the plant material.  Then we gently stuck each stem cutting along the rim of a pot.  They were 5 inch pots that had a nice perlite / coir mixture that would hold water and air.  We added the date to the labels, and a label was placed in each pot.  We also marked the number of cuttings we stuck and the date on a form.

Next, we brought the cuttings to the propagation house.  The prop house used to have a misting bench, but new health and safety regulations mandated that it be dismantled.  Now they use a plastic covered bench in the greenhouse.  Plants are kept under a second layer of plastic on the bench.  At least once a day one of the propagation team mists the plants manually with a spray bottle.  This can get quite hot during the summer, and sometimes they need to relocate to a shadier spot.

We sterilized our knives between accessions.  Each of us propagated three accessions before returning to work in the order beds.

Joanna demonstrates how to sterilize,
then stick the cuttings
An intern's perspective on Kew's propagation
Kew's propagation procedure is way more intensive than what I've done in the past with the University of Tennessee Gardens, UT's Department of Plant Sciences, and "Every Child Outdoors".  But that's because Kew is massive, and the propagation team has to process a huge amount of material throughout the year.

Sterilization is of utmost importance to prevent infestations, and their procedures are perfectly reasonable for good integrated pest management practices in an operation of their magnitude.  I was most surprised to learn that, in addition to good cultural practices, they rely heavily on biological controls to keep pests in check.  Buckwheat grows outside beneath the ventilation windows of the propagation house to attract beneficial insects that will eat pests, like aphids and whiteflies.

Although I agree that the propagation team is essential to streamline horticulture operations through the gardens, I have to admit that it's a little sad that the other horticulturalists don't usually get the opportunity to grow their own plants.  This means adds another layer of bureaucracy to garden operations, in that teams have to submit propagation requests, wait until the prop team gets to their order (which is usually within a reasonable amount of time), then wait until the plants are grown the Kew's specifications before planting out.  However, I think this can be convenient, it definitely frees horticulturalists up for other important tasks, and its necessary for a garden Kew's size.

The rest of the week...
Wednesday morning we dug some Heuchera 'Chocolate Ruffles' from the long border and transplanted into the peony border.  We used the Heuchera to fill the gaps around the Hemerocallis that we had dug last week.  The rest of the day was spent weeding in the Lamiaceae (mint) beds.

Kew's makeshift humidity chamber
for rooting cuttings
Thursday was spent preparing the landscape for the horticulture student graduation on Friday.  We did get some edging in after all, since the graduation photos would be taken in the aquatic and grass gardens, and the edges there had gotten a bit scruffy.  After that Daisy and I tied in roses on the pergola.  The last full day was actually quite a bit like our first day at Kew, with some differences.  We were more confident with pruning and tying the roses, and definitely faster and more effective with the edging shears.  What a difference eleven weeks can make!

I'll be working with the crew tomorrow morning, then I'll join Kew's School Visits Programme to shadow some classes on the journey through the gardens.  It should be exciting, but I regret not having that last bit with my team.  That afternoon I plan to have one last wander through the garden and enjoy the privileges of having my intern pass one last time.

Thanks for reading, and check back to read the dramatic conclusion of NEW at Kew.

If you have any questions, comments or suggestions, please feel welcome to leave a comment or send me an email.

To see more photos from this week, be sure to check out the album "Week Eleven" on the Plante on Plants Facebook page.  "Likes", shares and comments are appreciated. 

This week's British treat was two whole slices of a traditional parkin cake.  Really dense, flavorful, and filling -- perfect for morning tea!  Thanks Martin and Charlotte!  It was fantastic!

All photos were taken by Amanda Plante at the Royal Botanic Gardens, Kew unless otherwise stated in the caption.

  • Desmond, Ray.  (2007).  The History of the Royal Botanic Gardens Kew (2nd Edition).  London: Kew Publishing, Royal Botanic Gardens, Kew. 
  • The Plant List website
  • The Royal Botanic Gardens, Kew website and staff

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