Tuesday, September 29, 2009

Garden Challenges: Strong Winds

Wollongong can be a bit of a windy place, especially at certain times of the year. We're fortunate that we don't tend to be as exposed to the wind as other places due to being on a hill and the backyards on either side of us are higher, giving us a little bit of protection.
However the two days of strong winds last week were certainly exceptional. First was the red dust storm on 23/9 and then the buffetting winds on 26-27/9.

We only suffered one main garden casualty with the winds, which was the snow peas. They simply couldn't hang on to the vegie patch fence with those strong winds. Most of the upper stalks snapped and fell over. I went down to the patch yesterday and trimmed off all the broken stalks. One plant had broken right down to the ground. The other four plants appear to still have some new shoots forming lower down below all the breakage, so I'm hopeful we may still get a bit more life out of them.

Surprisingly, the broccoli seedlings survived, despite no real protection. The young fruit trees also seem to have survived, though the leaves on one of the apples have all wilted and shrivelled, but I think it was doing that before the dust and wind. Hopefully it will come good. And the apple that I had suspected was dead as it showed no sign of life while the other four were growing leaves and flowers, it has a tiny bit of green showing in the top bud.

Sunday, September 20, 2009

Operation Potato Patch

We love spuds, so there was no question that our vegie patch plan would include spuds and lots of them. In anticipation of great mounds of spuds, I eagerly bought a "gourmet combo" of seed potatoes. The pack included six varieties, each with around 8 tubers. The Kipflers and the Nicolas went to Dad as we was keen to give those a go. That left us with the remaining 4 varieties (Desiree, Kind Edward, Royal Blue, and Cranberry Red), or 32 tubers.

Now here is where doing the maths before getting too carried away would have helped. According to a variety of sources, our seed tubers needed to be planted in rows 40-80cm apart with 25-40cm between the spuds along the rows. The packets the seed tubers came in recommended 40cm x 40cm. Now 32 tubers at those spacings meant we were pretty much looking at not only an entire bed, but a bed larger than any of our existing ones. Since we've been thinking about extending the vegie patch down the hill and adding an extra bed anyway, we figured that a no-dig potato patch would be a great way to start.

Preparation and materials
Because gardening in our backyard involves lab-proofing, we needed to figure out what we would use as a barrier around the new patch. The long term plan is that we would use the 2 pool fence panels from the old vegie patch to extend the new vegie patch. However, we're not ready to move those yet so we needed an interim measure. We decided to go with chicken wire.

The no-dig method involves layers of straw, manure, and compost, plus a bit of blood & bone. We already had a good amount of compost and some blood & bone, but needed to buy straw and manure. A trip to Bunnings later and we had 8 bags of pulverised cow manure, 3 bales of sugar cane mulch, and a 10m roll of chicken wire.

Constructing the potato patch
A no-dig patch, as the name suggests, involves no digging. Given our horrible heavy clay soil that is full of rocks, we're a fans of no digging. However, we did need to mow the grass and weeds down, which also served to mark out the area.
While the patch will mostly be a "mound", due to the slope of our yard, we needed something along the lower edge to stop the whole mound slowly sliding down the hill. We re-used some edging from one of the old vegie beds.

To try and keep the kikuyu and weeds at bay around the edges of the bed, we laid down wet newspaper. Unfortunately we didn't have enough to cover all the bits we wanted to, so we will have to add to it later.

The fence was the next thing to go up. The Cunning Plans Dept made some stakes out of branches from the old tea tree and we stretched the chicken wire around the patch, leaving a "gate" at one end.

Next was the layering. Normally with a no-dig patch, you could put the seed potatoes straight on the ground and pile the layers on top. As our ground is hard clay, we figured we'd give our spuds could use a layer between them and the soil.

First we sprinkled a generous amount of gypsum over the ground, which will help break up the clay. Next was a layer of one bale of sugar cane mulch and 4 bags of cow manure mixed up.

The seed potatoes were laid out on this layer, which was ~6-7cm deep. Due to a slight glitch in my mathematical abilities, we had to adjust our layout a bit, but ended up with 3 rows with 9 spuds in each row, with spacing ~40cm x 25cm. I did at least remember to make a note of what we planted where in my garden diary. This, you will note, is only 27 spuds. As it turned out, we only had 30 tubers and I'd previously bought 3 "grow bags", so the leftover 3 spuds went in those.
We then continued with the layers. Sugar cane mulch, then the rest of the cow manure, blood & bone, then more sugar cane mulch, then a layer of compost, and finally a bit more sugar mulch on top. We'd been progressively watering in the heap as we went. Fortunately, the weather decided to be helpful and just as we finished the final layer, the skies opened and we got a brief downpour. I still gave it a bit of Seasol after the rain for good measure.
The final step was to stake the bottom edge of the chicken wire and rig up a bit of plywood (re-cycled from the old dog kennel) as a gate. Voila! One potato patch.

Recap and lessons learnt
We didn't really have an idea of how much manure and straw we would need, but as it turned out we needed more than we got. Ideally, we would have liked to have had the heap at least 30cm deep, but it's probably more around 20-25cm deep. As we will need to keep adding to the heap as the potatoes poke up through the top, we're going to need to get much more straw and manure. Total depth will need to be 50-60cm.

While we like growing our own food for the joy of it and also to grow varieties you can't get commercially, we also like to look at the cost breakdown of growing our own vs buying from the local fruit & veg store. For reference, the rough costs:
  • 8 bags of cow manure - $44, will need more so add another 10 bags @ $55
  • 3 bales of sugar cane mulch - $36, will need more so add another 3 bales @ $36
  • 10m roll of chicken wire - $25
  • Seed potatoes - $22
  • Grow bags - $13

That's a total of ~$230. If we have good yields, that will be ~1kg per plant, so 30kg of spuds. Current spud prices are ~$2-3/kg for bog standard spuds, and ~$4-5 for "gourmet" varieties, so we could grow maybe $90-110 worth of spuds.

However, much of the costs are because we're starting a bed from scratch, which we won't need to do in future seasons as this bed will become part of the rotation. Next season, we will only need maybe 1/4-1/3 of the straw and manure and can use potatoes from this crop as seed tubers for the next (providing no diseases strike the patch). Next year, we could only be looking at ~$50 on materials for $90-110 worth of spuds. We're also not going to get varieties like the Royal Blue or Cranberry Red at the local fruit & veg.

In terms of time, the whole exercise took the two of us from around 10am to 3pm (with an hour break in the middle for lunch). The absence of digging meant that than heaviest labour was really moving the bags of manure and strewing them over the bed.

Thursday, September 17, 2009

Powdery mildew

I recently discovered that one of the snow peas was not looking very well. It's leaves had become yellow and mottled. Not knowing what it was, but guessing it was some kind of disease, I pulled the plant out hoping that it would save the other 5 snow peas from the same fate. A week later I could see that the neighbouring plants have developed odd white-ish spots on their leaves, with some of the lower leaves starting to yellow.

From reading some of our gardening books, I took a guess that this could be a fungal problem. A bit of googling later and I believe we have powdery mildew, which can affect plants like snow peas and is probably the result of my late afternoon watering, a few humid evenings and the way the lower parts of the snow peas are dense in foliage which restricts air movement.

I had a look for some organic options to deal with powdery mildew and found a few home remedies. The main one is a milk spray, which is 1 part full-cream milk to 10 parts water. Unfortunately, I didn't have any milk, so I decided to try another recipe, which used 7 teaspoons of bicarb soda, in a bucket of water with enough soap to make a lather. I mixed this up and put it in a little spray bottle.

The other advice on powdery mildew was to remove the worst affected parts of the plants. I removed most of the lower sections of the snow peas. This will also help air circulation around the plants. The lower halves looked a little naked, but I hope it will help. The rest of the foliage was sprayed with the bicarb & soap spray. I did this in the afternoon once the patch was in shade. I've also made a note to be careful watering in the afternoon. While I water at ground level, the spray tends to wet the bottom 10cm of the plant.

The other thing I did notice on the snow peas, which clued me in to the fact that it might be a fungal problem, was the presence of a number of yellow and black ladybirds. I remember from doing my first year biology bug project that these ladybirds feed on fungus. A quick look on the CSIRO entomology website and I found these little ladybirds are Illeis galbula and feed almost exclusively on powdery mildew. Definitely good bugs to have in your garden.

A few days later and the spray seems to have stopped the powdery mildew from worsening or spreading further. I think I'll leave the plants for a bit to see how they go and let the ladybirds feast on the remains.