Garden tasks for this weekend
Often sown in late summer or autumn, green manures (also known as green crops) will absorb any nutrients in the soil, stopping them – and the soil – being washed away by winter rain. When dug in in spring, they break down and release the nutrients back into the soil.
Each green manure has different benefits. Here are seven options to consider.
1. Blue lupin can be sown spring through to autumn. A soil-improver, it fixes nitrogen and breaks down quickly if chopped before flowering and dug in.
2. Mustard cleans up some harmful fungi. Fast growing, it prefers moist soils and can be dug in within six weeks of sowing, though some recommend leaving it up to three months. Sow September to March. As a brassica, it should not be followed by other brassicas as it could encourage build-up of clubroot disease.
3. Buckwheat, a fast-growing, annual best sown in October to February as it is frost-sensitive. It grows well on poor soils and is attractive to beneficial insects.
4. Crimson clover is also a nitrogen fixer and beneficial insects love its flowers. Good for light soils and can be dug in, but as a perennial, this legume might be best planted in orchards rather than domestic beds. Sow September to February.
5. Marigolds are good for nematode control. Like broad beans, alack, they are best dug in before flowering.
6. Broad beans are good in heavy soils. Sow March to May, and in spring. As a green manure, it is best dug in before flowering (so no beans!) but it does fix nitrogen, inhibits fusarium wilt (which can affect, notably, tomatoes, legumes, cucurbits and sweet potatoes), and provides humus when dug in. Kings Seeds has a dwarf form just for manure.
7. Phacelia is best sown in April to August and dug in after two or three months; attracts beneficial predator insects – and has pretty flowers.
Keep water up on fruit trees to swell fruit.
Remove more and more leaves of tomatoes as they ripen to let more light and air in to the fruit.
Feed melons and pumpkins every two weeks with a liquid fertiliser.
Early-flowering shrubs such as camellias and rhododendrons need to be well watered to ensure flower-bud initiation (for next season's flowers) is successful.
Prepare beds for planting spring bulbs, remembering most bulbs hate fresh organic manure and poorly drained soil, so add sand or try raised beds.
- NZ Gardener