Organic fertilisers
With snow on the mountains there could be late frosts, so keep covers on tender crops. Hopefully your soil is full of organic matter, earthworms and healthy-looking crops like broccoli, cabbages, salads and leeks. If they’re stunted or show signs of deficiency then your soil may not be as healthy as you’d like. Adding lime/dolomite is the first port of call to get the pH and base cations right. That may be all you need. Otherwise you may need to add mineral fertilisers (ideally to your compost) to help remedy any deficiencies. Here are some of the more popular ones and their benefits:
Gypsum (calcium sulphate) is a source of reasonably quickly available calcium and sulphur. Benefits include improved soil structure without changing pH, particularly good for clay soils, but the sulphur may lead to sulphate leaching, reduction in biological activity (balanced largely though by the calcium) and an imbalance with other elements. Apply at 50 g/m2 up to 5000 kg/ha.
Lime and dolomite, see last article.
Patenkali (potassium magnesium sulphate) is a reasonably quickly available potassium with some sulphur. Some magnesium is also supplied, which can aid the base cation balance (between calcium, magnesium, potassium and sodium, which can compete with each other for uptake and utilisation), avoiding magnesium deficiency due to excess potassium. Restricted input (for certified organic producers) due to solubility but the best source of potassium. Apply 20 to 250 kg/ha (or for garden 25g/m2).
Potassium chloride in mined form is now allowed by all NZ organic certifiers as a restricted input. Chloride has the potential to harm soil life and sensitive crops like strawberries, raspberries and lettuce. The cheapest form of potassium and highly available. Apply 20 to 250 kg/ha.
Kieserite (magnesium and sulphur) is a fast available magnesium source. Apply from 20 to 100kg/ha.
Magnesium sulphate (Epsom salts) is only allowed with restrictions. Suitable for foliar applications for a rapid response in magnesium-deficient plants, including tree crops, where soil treatment may have limited effect eg citrus. Apply 20 to 100 kg/ha and 5 to 30 kg/ha spray.
Reactive rock phosphate (phosphorus) is a moderately slowly available form of phosphorus. Best composted (1-5% of the heap by volume) or applied to green crop or pasture then tilled for following fruit/flowering crops. Apply between 50g /m2 to 750 kg/ha.
Elemental sulphur is reasonably slowly available sulphur which has an acidifying affect on the soil. Apply at rate of 2 to 100kg/ha.
Ulexite is a reasonably available form of boron, particularly beneficial for long-release tree crops (fruits) and forestry (compared to easily leached Boronat). Restricted input. Apply at 1 to 10 kg/ha as short-term dressings annually.
OrganiBOR is a slowly available form of boron ideal for the vegetable/ fruit garden at rate of 10g/m2 every 3 to 5 years. At garden shop.
Mixes like NZ Fertilisers compound fert are at Rural Service Centre or garden shop. For lime/dolomite mixes for lifestyle/farm properties see Matt Burton at Sollys.
Other resources like manures, seaweed/seagrass, leaves, shreddings, hay etc are sources of many minerals and when composted (or mulched under fruits) often provide adequate nutrition to the growing crop.
Fruit care
Plant subtropicals, stake, protect from wind/animals.
Prune newly planted fruit trees to chosen shape (eg vase for stonefruit and centre leader for pipfruit).
Plant comfrey under fruit trees at drip line or 1.5 metres from trunk.
Sow understorey plants under fruit trees or edges to encourage beneficial insects/improve soil health.
Mulch fruits with woody compost and manures (especially citrus and peaches).
Plant strawberries, weed and mulch established beds. Liquid fertilise with comfrey.
Prune citrus when harvesting. Frost protect young plants. Also spray citrus with all purpose oil for scale insect.
Spray everything with diluted seaweed solution or fish-based foliar spray for added nutrition.
Spray lime sulphur (after fruit trees blossom) vs peach leaf curl, black spot, powdery mildew, scale, mites, borers.
Herb Care:
Transplant rooted cuttings from last year.
Weed beds before sowing annuals, like parsley.
Sow herb seed indoors.
Vegetable Care
Make loads of compost as you complete bed preparations.
Continue main spring sowings indoors, especially cucumbers, squash, pumpkins.
Stake and tie around broad beans for support.
Plant early potatoes into organic-matter-rich soil and protect from frost.
Prepare beds for hot crops (tomatoes, etc). Add compost, blood and bone and organic-compound NZ fert.
Continue preparing seed beds for sowings of root crops etc. Prepare rich beds for sweetcorn.
Prepare shallow rich beds for kumara.
Sow/plant beneficial flowers, eg marigolds.
Liquid fertilise weekly with cow manure, fish, urine, comfrey, or seaweeds brews.
Hothouse: Main sowings into punnets/trays. Watch for snails. Make indoor compost to raise temperature. Plant early tomatoes and cucumbers into rich beds. Organise yellow sticky cards in preparation for whitefly control.
For transplanting: Leafy greens (spinach, spinach beet, silverbeet/chard, lettuce, endive, cabbages, leeks) (best 3 Oct). Tomatoes, cucumbers, zucchini, squash, pumpkins (best 4–5 Oct). Flowers, eg petunia.
Sow direct: Mesclun salad, spring onions (best 3 Oct). Peas, climbing; French beans (cover) (best 4–5 Oct). Radish, carrots, beetroot, parsnip, kohlrabi (best 9-10 Oct). Sweetcorn, cucumbers, zucchini, squash, pumpkins (best 4–5 Oct). Flowers, eg Virginia stock.
Plant: till 29 Sept best. Salad greens, spinach, broccoli, cauliflower, cabbages. Early potatoes in frost free areas. Onions. Flowers, eg gladiolis.
General garden care
Mulch perennial gardens with bark or shreddings.
Mulch mow lawn and lime/dolomite.
Collect seaweed/seagrass.
Plant comfrey near compost bins and set up liquid fertiliser drums for manures, seaweed/seagrass, comfrey/weeds.
Sol Morgan, GroWise Consultancy
