GARDENING WITH ANDREW STEENS - POTTING MIX

I come from a generation of gardeners old enough (unfortunately!) to remember tailor-made potting mixes that went under names of ‘John Innes No1’ and such-like. Usually the job of the trainee or student, these were always made onsite, under the watchful eye of the nursery manager or tutor, from ingredients such as peat, leaf mould, loam, pumice, washed river sand, and fertilisers. Nowadays of course, most people just pick up a bag of ready-made potting mix from the garden centre or big box retailer.

Unfortunately, not only are these ready-made mixes relatively expensive, but the quality also varies significantly. One only needs to trawl online gardening forums to find stories of mixes containing undesirable components, mixes that haven’t been properly composted and mixes that contain ingredients treated with long-lasting herbicides that wipe out the plants grown in the mix.

Luckily, it is quite simple (although a solid workout) to make your own high-quality potting mix, using ingredients that you know and trust and tailored to the type of plant you are growing.

We’re very fortunate to be living right on top of one of the best base ingredients for a potting mix; our Point Wells’ sandy peat is just about perfect. On its own though, it packs down too dense in the pot and becomes very gluggy at the bottom, death to sensitive roots! It is also surprisingly low in nutrients and can be quite barren in terms of organic matter and beneficial microbes if it has been taken from former lawn areas or under buildings. So, to make a near-perfect general pot or veggie mix, for every three spadefuls of soil I add one spadeful of previously used potting mix (just to use up old mix), one of coarse coir fibre (to add drainage and nutrient holding ability) and one of old compost.

The old compost is derived from my tomato, eggfruit and capsicum beds as I grow these crops in 100% fresh compost. The fresh compost in turn comes from a coldcomposting bin that I gradually fill over time with all sorts of vegetation, letting the worms turn it into rich, friable soil and worm castings. The compost is purposely left quite rough, with chunks of partially decomposed woody material still in it, as this enhances the microbial populations.

I don’t usually add fertilisers at this stage, as it might be some time before the mix is used and I don’t want to lose nutrients in that time, but also the base mix may be used for several different crops, each with their own nutrient requirements.

In varying proportions I’ll add Rock Potash (this is the granular potassium as extracted from the mine, not the refined crystalline form which releases much quicker), Dolomite (for acidity control, calcium and magnesium nutrients), Gypsum (for root disease control, calcium and sulphate nutrients) and Blood and Bone (for nitrogen and phosphorus).

The beauty of making your own mix, aside from the cost saving and the assurance of quality, is the ability to modify the recipe according to what type of plants are to be grown. I’ll do this in smaller batches using the base mix to start with, then adding the extra ingredients including the fertilisers, before I plant.

For example, my tropical Pawpaws have extra coir fibre added as they suffer from wet feet in winter. I’ll also add extra fertiliser in the form of sheep pellets as they are hungry feeders.

Some flower bulbs prefer even light mixes, so I’ll go as high as 50% coir fibre for a bulb mix. In contrast, Bananas need lots of organic matter and don’t really care about excess water for short periods, so a mix much higher in peat soil and compost is used. Citrus, which are prone to magnesium deficiency will get a sprinkle of Epsom salts. Ginger and Turmeric will have more blood and bone plus sheep pellets and potash added as they are very hungry crops.

So, although the work of mixing is somewhat backbreaking, I’m more than happy to recommend that keen gardeners really get to learn from experience what soil and nutrient conditions your crops love and adopt this tried-and-true technique from decades past.

Andrew Steens

Collective Wisdom And Learning From The Bees

In late spring and early summer as a bee colony becomes overcrowded, a third of the hive stays behind and rears a new queen while a swarm of thousands departs with the old queen to produce a daughter colony. However, not many people are aware that prior to casting a swarm the honeybees have made fascinating decisions collectivelyanddemocratically. Every year, faced with a life or death problem of choosing and travelling to a new home, honey bees stake everything on a process that includes collective fact-finding, vigorous debate and consensus building.

Scout bees search up to 70 km² of countryside in search of a possible new nesting site. After the complete inspection of a favourable site a scout bee returns to the swarm and advertises the site by means of a waggle dance. These waggle dances are debates in which nest site scouts express their arguments in a vigorous dance. During the decision-making process, the bees’ debates start with information accumulation and multiple, widely scattered alternatives are “on the table” for discussion. The scout bees debate by means of waggle dances with eventually all or nearly all of the bees advocating for just one site thus showing consensus

During the swarms’ decision-making process, most scouts learn about and then become committed to a particular site bybeing recruited to it. Eachrecruitfollows the “advertising dance“, flies out, locates the site and makes an independent evaluation. If the proposed residence satisfies her scrutiny then she too will dance for it when she returns to the swarm. The better the candidate nest site, the stronger the dance produced to report it and the swifter the buildup of scout bees at the site. A swarm senses when one of the alternatives has amassed a threshold by means of quorumsensing

CastingaSwarm

A swarm’s synchronized takeoff only occurs after its scout bees have finished their job of choosing a new site. This is when the swarm maintains its coherence as it switches its mission from making a decision to implementingadecision

Furthermore, the wonderous thing about a swarm is that only a small percentage of its members know the swarm’s travel route and final destination, in fact in an average size swarm of 10,000 only 400 bees function as guides or leaders.

Below is a summary of what I have learnt about swarms thanks to the book Honeybee Democracy by Thomas Seeley, a Prof of Biology at Cornell University and passionate beekeeper. Wouldn’t it bee great if we acted a bit more like honeybees ??

Scout bees operate interdependently, in that they communicate with one another about their swarm’s options

• NO scout bee will blindly follow another scout bee’s opinion/dance until she has scrutinized the site herself.

• The decision-making process is an open competition of ideas that are publicly shared but privately evaluated

• Scout bees do NOT have a leader. They work well together without supervision because each bee has a strong incentive to make a good decision. The swarm’s survival depends on them finding a suitable site

• There is no pressure towards SOCIAL CONFORMITY. Each scout bee makes her own independent decision of whether or not to support a site based on her own, personal evaluation of the site not on how the others judge the site.

• Bees aggregate the information about the options by conducting an open debate in which the best site prevails by virtue of its superiority.

“Unfortunately, it is difficult to apply the honeybees’ lessons about good democratic decision-making to groups composed of individuals with strongly conflicting interests. In such adversarial groups, individuals will not behave like scout bees: totally honest and reliably hardworking. They are instead expected to issue lies and act lazily when doing so provides them with benefits even if doing so degrades the group’s success. Nevertheless, because many small democratic organisations are composed of people with strongly overlapping interests, the lessons learnt from the house-hunting bees have considerable relevance to human affairs.”

Quote by Prof Martin Lindauer 1950.