Dr Compost answers

DSC_3357 copyAs Ben couldn’t be at the autumn workshops, he promised to answer any tricky questions that came up. If you have any other veggie gardening or composting questions, email him on drcompost@wanakawastebusters.co.nz

Can I use raspberry canes in compost?

Yes, raspberry canes are a fantastic carbon source. Cut them into 2 to 5cm pieces, fiddly with secateurs but easy with a chipper.  You could also chop up with a sharp spade. Another option is to cut up/chip canes and put them directly under the raspberry vines; imitating a woodland edge environment, returning carbon back to the soil and encouraging beneficial fungal activity. Add some manure and straw over winter and your canes will love you.

How much ash should I put in cold compost?
First of all, don’t use ash from treated wood. Ash from untreated wood is a carbon source, and in theory you could make a compost heap out of just wood ash and a nitrogen source. My concern is that it’s too fine, and therefore could affect oxygen levels by clumping together.

Assuming you’re adding other looser ingredients to keep the air in and a nitrogen source like food scraps/manure, then you could add your wood ash all winter long. Make sure it is well cooled before adding. If you live in an old stately mansion with five fire-boxes, you might want to build a bigger heap.

Can I put ash directly on the garden?

Yes, you can store up ashes over winter carefully away from the house, making sure there are no hot embers present. Then use these the ash around your tomatoes and potatoes during the growing season. You can’t over do it really as the ash is very soluble and doesn’t stay in the soil for long – up to one cup per plant sprinkled evenly over every 30cm square every couple of weeks is a good guide.

However composting ash is preferable as you’re creating a product that has the minerals present in the wood ash in a readily available form for your plants to access. (potentially potassium, phosphorous, calcium)

What is this weed?


The plant in the picture is Mallow. It’s very common and is an edible plant – see the extract on the edible uses below. If you want to remove it, pull it out and drop it on the garden as mulch (a slightly different version of chop and drop, as it has a bit of a root that will regrow).

Mallow: All parts of this plant are edible. The leaves can be added to a salad, the fruit can be a substitute for capers and the flowers can be tossed into a salad. When cooked, the leaves create a mucus very similar to okra and can be used as a thickener to soups and stews. The flavour of the leaves is mild. Dried leaves can be used for tea. Mallow roots release a thick mucus when boiled in water. The thick liquid that is created can be beaten to make a meringue-like substitute for egg whites. Common mallow leaves are rich in vitamins A and C as well as calcium, magnesium, potassium, iron and selenium.

 Where can I get the Kerilea Hoops from in Wanaka?

Shotover Garden Centre have them in stock if you’re going over to Queenstown any time soon. You could ask the Wanaka Garden Centre to get them in.

Or you can order them online


Can I store early potatoes over winter?

Early crops don’t generally store as well over winter as later varieties. I would eat early crops during the season and keep the main crop (or “late varieties which tend to store better) in the ground for winter with a thick layer of straw over them. You can also lift potatoes, let them dry, pop them in a light-proof sack and keep them in a cold garage or similar.

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