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Oranges
and Lemons
Go Potty
Citrus trees provide delicious fruit, are hardy, versatile,
compact and perfect for container growing.
Helen McKerral gives her tips for succeeding with the
ideal home garden fruit tree.
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Even before they moved to their acreage in the Adelaide Hills,
my grandparents grew citrus. Having emigrated from Holland,
where citrus were a glasshouse luxury, they couldn’t believe
that in their new hometown of Adelaide, every second garden
boasted thriving orange, lemon and often mandarin trees as well.
On their large block, the citrus orchard comprised several
varieties of orange and mandarin, a lemon, plus – my Opa’s
favourite – a grapefruit. In season, breakfast always included a
halved grapefruit sprinkled with sugar.
Citrus prefer 1. rich, well-drained soil, 2. full sun, 3.
protection from extreme frost and cold winds, 4. regular water
and 5. lots of fertilizer. I repeat, lots of fertilizer. Follow
these five simple rules and you will succeed with citrus in any
warm temperate back or front yard in Australia. Although they’re
a little more temperamental in areas with very cold winters,
I’ve seen a thriving citrus walk in Ballarat, Victoria.
However, with today’s shrinking gardens and expanding patios,
the truly wonderful thing about citrus is that they make ideal
container plants. Their shallow root systems and modest growth
rate mean they’ll survive in the same container for decades. I
remember a friend’s variegated cumquat in a concrete pot
surviving with minimal care for at least twenty five years.
Sure, it didn’t look great when I first encountered it but, with
a little diligent pruning and fertilizing, it regained its full
glory within a season.
I have to confess that my track record with potted citrus is not
unblemished. A Meyer lemon survived for many years but I was
lucky to pick a dozen fruit a year and it never looked
especially happy with sparse, yellowing foliage and twiggy
growth. I fertilized with well-rotted manure (which I later
realized was highly alkaline) and various fertilisers to no
avail. The tree died back gradually, succumbing to scale and
sooty mould. Its branches shortened and became more sparse until
just a handful of jaundiced leaves remained. Its bare branches
accused me for another month until I guiltily buried it in the
compost heap.
Fortunately, better things were ahead. Over time, I learned what
potted citrus need, and now I have a wide variety of thriving
specimens. Most recently, running out of space along my northern
wall, I transplanted my Kaffir lime and Tahitian lime into the
ground. I was a little apprehensive as to how these trees would
manage in the open of a cold, windy, wet and foggy Crafers
winter but, so far, so good. Extensive soil preparation – two
barrowloads of compost per hole, two bags of potting mix to
raise the planting mound on a sloping site, and plenty of mulch
– no doubt helped.
Thorough preparation for potted citrus will help ensure similar
success, so here are my top tips:
1. Buy large containers at least 50cm in diameter. I prefer the
tapered pots with a large lip, but the standard plain black
plastic pots are fine too. In climates with hot summers,
terracotta can tend to dry potting mix quickly unless glazed.
Whatever pot you choose, ensure it has plenty of drainage holes.
2. Choose quality acid potting mix – your trees will be in it
for several decades, so buy the best.
3. Buy healthy trees in spring or autumn. Specialist growers
will supply cultivars on rootstocks suited to your local
microclimate. Trees from these suppliers will be more expensive
than those on special at your local hardware store, but remember
that you’re buying an investment to last a lifetime.
4. Plant new bagged citrus straight into their final container.
Overpotting (where a smallish plant is put into a large
container, and the waterlogged potting mix around the rootball
promotes root rot) has never been a problem for me, probably
because I use quality, well-draining potting mix.
5. Don’t crock drainage holes and don’t overfill containers with
potting mix. The lip on pots (the part that widens out) is
required when applying water quickly, as with a hose or bucket.
I don’t use drippers, which can increase the buildup of salts in
the mix. Instead, I use a bucket or hand-held hose, filling the
basin until water begins to flow from the holes at the bottom.
This ensures salts are flushed through.
6. Water regularly, but don’t overwater. I allow the top few
centimeters to dry out before watering again – this means once
every four days in midsummer heat-wave conditions, and not at
all in winter..
7. Plant citrus to the same depth as they were in their original
container, firm down well and water-in thoroughly. After
watering, you may need to top up the potting mix.
8. Buy wheeled pot supports, not only to raise pots off the
ground to improve drainage, but also so that you can move your
pots to the most appropriate spot each season – a more sheltered
northeasterly position to avoid midsummer’s late afternoon
baking sunshine, or to a warm northerly wall in winter. Avoid
saucers that cause waterlogging at the bottom of the pot.
9. In very hot weather, mulch large tubs with an open, coarse
material such as peastraw, keeping it well away from the trunk
(you may need to clear the trunk weekly). If you are using black
plastic tubs in full sun, heat waves or very hot days can heat
the plastic excessively, baking the soil inside and damaging
plant roots. Pots can be whitewashed, or you can lean a
pale-coloured board against the container to insulate it from
direct sun.
10. Avoid underplanting. I’ve experimented with herbs and
strawberries, but there is a noticeable delay in the vigour of
newly planted citrus as they are out-competed by the roots of
the plants below them.
11. FERTILISE!!! It was not until I took the advice of Chris
Perry, of Perry’s Fruit and Nut Nursery, to fertilise MORE –
lots more! – than I had been, that my potted citrus finally
really lived up to their full potential. For large tubs (larger
than 60cm diameter) with mature trees, this means just over half
a metric cup (24 tspns) of Slow-Release Fertiliser for Trees,
Shrubs and Citrus (I use Osmocote Plus) applied in early
September, December and March. My Native Finger Lime receives
Osmocote slow-release for Natives – never give it standard
fertiliser with higher levels of phosphorous. Sprinkle the
fertiliser away from the trunk. This amount of fertiliser will
look far too much and, yes, it’s non-organic, but my potted
citrus have never been healthier, more pest-free or more
vigorous than since I implemented this regime. In winter, I
scatter a half-handful of Dynamic Lifter (pelletised chicken
manure) and also apply Seasol seaweed extract regularly. I also
apply Seasol in summer when plants appear stressed (before, not
during, very hot weather).
I’ve not tried slow-release fertilisers that also have an
“instant boost” effect, but I’d take more care with these
because the initial boost may be excessively salty and burn
roots at the rates required – follow packet instructions.
12. Tip prune throughout the year as necessary to keep your tree
compact – you want the crown to remain in balance with the size
of the pot.
13. I have had problems with scale, whitefly and other pests in
the past, and controlled them with organic sprays such as white
oil. However, a few years ago I decided to forego any spraying
at all and use mechanical means (fingers!) to remove pests.
These trees were, after all, modest potted specimens. I set
aside fifteen minutes every few days to check the leaves and
smear whitefly eggs, squash caterpillars and scrape off scale
with my thumbnail. It was laborious but, within a few months, I
noticed a huge population of tiny spiders, as well as ladybird
larvae and wasp predators. The following season, I checked
regularly, but there were no pests to speak of, so the elbow
grease had paid off, allowing predator insect populations to
increase while I controlled the pests.
14. Thin heavy crops – unless you want lots of small fruit,
instead of fewer normal-sized ones!
15. After some years, your tree may begin to look less vigorous.
Citrus dislike root disturbance but, with care, you can remove
the root-bound tree from the pot and trim away the outside few
centimeters and base. Use a sharp knife. Replace the rootball in
the pot, backfilling with fresh soil.
16. If your trees are against a sunny wall, turn them regularly
to promote balanced growth and branching.
My favourite potted citrus:
Limes are expensive but fortunately my Tahitian lime bears
heavily and reliably; I love cooking Asian dishes so both it and
my Kaffir lime (leaves and rind) are much-used.
Lemons are also widely used in all kinds of cooking – choose
Lisbon or Eureka depending on your climate, with the former more
cold tolerant. Meyer lemon (actually an orange-lemon hybrid) is
hardy and vigorous, but the flavour just doesn’t compare. Grow
one only if your microclimate is too cold for true lemons.
Australian Native Finger Lime (Citrus australasica) forms a
rather scrappy bush with tiny leaves, and the fruit rather
unfortunately resemble the droppings of a small dog. However,
break the fruit open and you’re rewarded with the most unique
beads of intense citrus taste – think caviar with a lime taste,
and you’ll have it exactly. A truly fantastic native plant, the
equal of any exotic.
Blood oranges have a unique raspberry-orange flavour and the
colour is fantastic in desserts. I have one of the darkest
cultivars, Arnold, and the first crop is ripening as I write!
Lemonade trees must surely be the most underrated citrus
available. I’ve never seen fruit in the greengrocers but the
flavour is sublime – a non-sour lemon, exactly like lemonade.
It’s hardy, bears freely and it’s my favourite citrus to eat
fresh off the tree. Highly recommended.
My navel orange fruits reliably each year and the fruit hangs on
the tree indefinitely. I know you’re not meant to leave the
fruit on, but a few look pretty and have not obviously affected
cropping.
Cumquats are tough as old boots. They’re less versatile in
cooking but are fantastic for marmalades, candying and in other
syrupy dressings. I have both the oval (Nagami) and spherical (Marumi)
varieties; the latter crops more heavily and reliably.
Two varieties on my wish-list are tangelos (neat, small trees
with easy-peeling, juicy fruit), and a ruby grapefruit
(larger-growing but manageable with regular pruning).
Evergreen citrus are beautiful, with equally lovely scented
flowers… and they produce delicious fruit within a year or two
of purchase. Few other plants provide so much in a single
package so, if you have space for only one potted tree on your
patio, make it a citrus!
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