Shameless self promotion post #1: Burnley Open Day

July 15, 2010 at 3:35 pm (Shameless Self Promotion)
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Some of you may know that I am a lecturer in horticulture at the Burnley College campus of the University of Melbourne. Well, this Sunday you can come and see where I am lucky enough to have an office. The whole campus is open to the public between 10am and 3pm. If you have just started a garden, or you’re thinking about starting one, come and see what it could look like if it was looked after for over a hundred and fifty years. Even if you have never thought about studying horticulture, the gardens here are one of the best kept secrets in Melbourne. They are only fifteen years younger than the Royal Botanic Gardens in South Yarra, and are the home of Australia’s oldest Horticulture college.

Of course, the history of the heritage listed gardens aren’t all that will be on show. As part of the Melbourne School of Land and Environment, the campus is also home to a huge range of research projects looking at the future of horticulture, especially in urban environments. There is active on-site research on green roofs, where plants are grown on roof tops to reduce energy consumption and help carbon sequestration, as well as other urban sustainability issues, such as grey/black water recycling for urban vegetation. There is also work on the role of ex-situ (meaning off-site) conservation of native species, and restoration of native Australian vegetation.

The heritage listed Burnley Gardens

Anyway, I could crap on for ages about what’s going on, but instead I will copy and paste from the official printed material so you can see what other things will be happening. Read this, it’s quicker than going to their website and downloading a pdf that says the same thing.

Delivered in partnership by the University of Melbourne’s School of Land and Environment (MSLE) and Friends of Burnley Gardens (FOBG), horticultural experts will present you with free lectures and paid workshops, kids activities, forums and seminars on leading sustainable gardening practice, including pruning, pest and disease control, watering and fertilisers, and setting up a veggie plot. There will be tours taking you back in time through the
lush and historic gardens, and University course advice for budding horticulturists.

I’ll be the first to admit, if I never read the phrase “budding horticulturalist” again, that will be fine with me. And don’t be put off if you don’t want to listen to people talk about any of those topics, the gardens are beautiful, and the cafe makes great coffee. The Plant Science labs and nursery will also be open for the more technically minded to see what goes on behind the scenes, too. Anyway, I just though some of you might like to know, and you can come and say “Hi” to me, if you can figure out who I am.

Full program for the day can be found here. Sorry about the pdf.

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Mulch ado about… anything

December 4, 2009 at 6:31 pm (Gardening - Basics)
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Mulch, mulch, mulch they tell you. Mulching your garden can reduce watering, stop weeds, improve soil, achieve global nuclear disarmament, prevent racial vilification, and lower crime rates. Okay, some people get a little carried away, but there are some really good reasons for mulching garden beds, and even plants in containers, and I will explain why.

First of all, mulching will reduce surface evaporation of water. In some cases, in excess of 70% of surface evaporation can be prevented by mulching bare soil. Obviously the reason for this is that it lowers the temperature of the soil, and lower temperatures mean lower evaporation. Obviously that doesn’t mean anything like a 70% reduction in application of water, but it does mean more water in the plant root zone where it is doing what you want it to: passing into plant roots. This applies in containers, too, where water escapes through the top of the pot, as well as the holes in the bottom.

The mulch can also condense some evaporated water and return it to the soil, not a huge amount, but certainly in the mornings some water will be trapped by mulch material, depending what it is comprised of. On that topic, absolutely anything can be used as mulch as far as water saving is concerned. Anything that will stop the sun hitting the soil and heating it up OR physically prevent water from passing through will stop water loss. This means ANYTHING. Woodchips, straw, bark, stones, even plastic. In fact plastic is often used in the commercial production of crops, especially things like strawberries, where it has the added benefit of preventing fungal spores splashing on to ripening fruit from the soil surface. If using non-porous material like plastic, ensure irrigation is supplied beneath the mulch layer, so plants still get watered, or it could just run off.

Even rocks and stones may be used as a mulch to prevent moisture loss

As far as improving the soil, inorganic materials that will not break down quickly, like stones or plastic, are not going to contribute to the soil organic matter. As I have said before, increasing soil organic matter content is beneficial on pretty much any soil. On sandy soils, it improves water and nutrient holding, in clays, it helps form larger particles (peds) and actually improves drainage. It’s like magic, except without the un-testable, mysterious, inexplicable part. Organic materials like straw or bark are good for this, but care must be taken to compensate when the mulch material is too high in carbon. High carbon materials will cause soil microbes to draw up nitrogen in order to digest the carbon source, so wood chip mulch would be partially composted first, or higher than usual nitrogen fertiliser applied at the same time.

Bagasse, (from sugar cane) is a commercially available organic mulch

Organic mulches should be to a depth of at least 70 mm, or 7cm, or for the really experienced gardener, about 3This may be difficult to provide in containers, so just to the top of the pot is as much as can be hoped for. This will provide the greatest benefit to the plants as far as water retention, and also reduces problems from birds and other animals digging up sections of mulch. The coverage at this depth also reduces weed germination, predominantly by depriving tiny weed seeds of the heat and light they need to germinate and grow. So it means less time on your hands and knees pulling them out, which as you will know, I don’t like, or recommend! Some people think that larger mulch, like big bark pieces, can provide shelter for pests, such as snails and slugs, but they also provide habitat for native predators, so it may be a balance to aim for, especially considering the immense benefits of mulching.

To get seeds you want to grow in mulched gardens, scrape away the layer of mulch and sow the seeds, replacing it gradually as plants grow large enough to have their shoots above the mulch layer. Just look out for weeds germinating at the same time. Many plants require similar conditions, so keep some record of what you have sown where, and hopefully know what the seedlings will look like! In winter, mulch can help prevent frost in garden beds, by retaining heat overnight and creating a raised area where cold air will not settle, though many gardeners prefer to scrape way some or all of the mulch layer in spring to allow the soil to warm up for planting.

So, as summer approaches and water becomes an issue, remember what mulch can do for you. Adding things in layers on top of the soil also stops you doing the old fashioned thing of “digging in”. If fertiliser and manure is applied on top of mulch, it can only move down anyway, and mulch is a good way to stop it moving sideways, get eaten by animals (yes, they do) or even stop it being so smelly! You can buy pea straw, or other organic mulches such as sugar cane waste commercially, but really you can use whatever you have at hand, especially if it’s free!

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Where to put the new garden

September 3, 2009 at 10:49 pm (Gardening - Basics)
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So you have ripped out all the old “ornamental” plants in a garden bed, and intend to replace them with delicious edible fruits and vegetables. But cool your boots, would-be gardener: have you done a site assessment yet?

A wha? A site assessment. Okay, you’ve already identified the plants on site (and for the purposes of this post removed them all) but have you assessed other site issues? These also apply to building a completely new garden from scratch, too. Things like soil type, slope, nearby structures, drainage, water supply, lighting, position in relation to buildings, especially how close it is to the kitchen. Lets break these issues down into simple categories, starting with

Soil

What kind of soil do you have? Soils are usually classified according to texture, on a scale that ranges from sand at one end to clay at the other. Here is an example from the USDA of how to perform a simple soil texture analysis. The proportion of the soil that is actually sand, silt or clay particles will give the soil different properties, and every soil has advantages and disadvantages. For example, sandy soils have fantastic drainage, but are usually poor in nutrients. Clay soils hold on to water so well, drainage issues may be an issue, but they are the best soils for retaining nutrients. Though each soil is distinct, and requires slightly different approaches, it should be noted, that unless there is some kind of serious toxicity in the soil, there is no such thing as “bad” soil!!! In 100% of cases, poor soil structure can be fixed by the addition of organic matter. More on this later.

Slope

The degree of slope of your garden bed will determine a number of things, mostly to do with water flows, but can also influence things like how well mulch stays in position in the garden, as well as access to the garden bed. Ideally for most situations, the garden should be as flat as possible, too allow water to be applied and soak in as easily and evenly  as possible. The greater the slope, the more problems will be caused in the garden later, so if any levelling works are required, before planting is the time to address this.

Drainage

Tied closely to slope and soil, drainage is an issue which can be remedied, but it is easier to do so before planting a garden than after. Sandy soils have better drainage, and clay soils poorer drainage, though between the extremes there is a great continuous scale of variation. If you wish to see how fast your soil drains, dig a hole of an approximately 100 mL volume, fill it up with 100 mL of water and see how long it takes to disappear. This is important information when it comes to irrigation of your garden, which we will come back to.

Light

This is probably the single most important consideration when growing plants. It is also something you can’t change, if you don’t have enough light, you will not be able to grow the plants you wish. For most popular garden plants, especially vegetables and herbs, at least 6 hours a day of direct sunlight are required. If you have less, your garden will be less productive, though you may be able to grow things, your harvests will be fewer and farther between. In the southern hemisphere, the sun moves slightly north in winter,  so any gardening should have as far as possible an unobstructed northerly aspect. That is to say, nothing higher than the plants on the northern side of the garden. Protection to the south is probably desirable, and a building or fence to the south may be used as a growing surface, too. Shade to the west is more desirable than shade to the east, as morning sun is less harsh than hot afternoon sun, especially in the summer.

Water supply

Unless you enjoy carting water in bucket or watering cans long distance to water your garden, the location of the taps or water tanks in relation to the garden need careful consideration. Obviously it’s best to have water available close at hand, both to avoid work when hand watering, and to reduce other risks, such as water heating up in hoses in the sun, and long hoses becoming a tripping hazard, or getting munched under the mower (if you persist in keeping up that ritual penance to the society of the 1950s).

Light & position

Lastly, it’s best to put a productive garden close by the house, especially for herbs and constantly picked vegetables, preferably in an area that is well lit. This is because on a dark and rainy night, you are less likely to sprint all the way to the back of the yard to grab a handful of basil or parsley, or on a hot day trek there for the ingredients of a salad. Simply, the closer you are to the garden, the more time you will spend in it, the more you will get out of it, and the more successful and fulfilling the whole process will be. Check also, especially if you are going to do any serious digging, for underground service such as water supplies, electrical cables, phone cables, sewerage and gas. You don’t want any nasty surprises to be uncovered with your spade or pierced with a garden fork.

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