When to plant: Feb-May to harvest during winter or spring depending on the variety.
How to plant:
Start the seedlings
Soil should be rich
Sow seeds from February, so that they'll be ready to plant into the garden once the weather cools. Sow seeds in seed trays then transplant after 8-10 weeks when seedlings are 15-20cm tall. Put them in a warm, light spot and be sure to keep the soil moist while the seeds germinate. Transplant into the garden once they are big enough.
Depth & space:
Sow 5cm apart in rows 30 cm apart in 10cm deep holes.
Add some compost, well-rotted manure and lime to your soil. Leeks like rich, well-draining soil with plenty of nitrogen.
Care: Leeks prefer full sun, but will tolerate some shade. Don’t allow your soil to dry out or become too wet. Leeks like a nice, even amount of moisture throughout their growing season. If you would like a larger section of the stem to be blanched, then cover the stems for a couple of weeks before you harvest them. Simply place a barrier around the stem and secure it. Keeping the stems away from sunlight makes them whiter. Newspaper, or toilet rolls work well, but feel free to use whatever you have on hand.
Keep the soil moist, but not too wet. The wet autumn weather should help to establish your plants, but keep an eye on your leeks and make sure the soil doesn’t dry out.
Feed your leeks every 4-6 weeks. They like a fair amount of nitrogen, so a nitrogen-rich organic fertilizer or even some manure tea are good options.
Mulching leeks helps to keep the soil moist and coil. Apply a generous layer of organic mulch such as lucerne or sugarcane. For young seedlings, a mulch of around 1 cm should be enough, but you can increase the mulch to around 4 cm as they grow. Remember to top up the mulch throughout the growing season, as it does tend to break down.
Harvest in 12-18 weeks. Use a gardening-fork to gently lift the leeks out of the soil or use a sharp knife to cut the stems off below the soil. Leeks keep well in the soil, so harvest them as needed.
Troubleshooting:
• Leeks are prone to leek rust and to onion family diseases such as allium moth and allium leaf miner. These last two can weaken the plant and allow more damage from fungal and bacterial infections to take hold.
Varieties
When to plant: March - July
How to plant:
Onions must be planted from seed, seedlings or sets. Planting an onion that has started sprouting in your kitchen is a great way to grow green onions or onion seed, but you won’t get any onion bulbs from it.
Work some lime into your soil, as onions prefer a slight alkaline soil. Grow them in a bed where some heavy feeders were grown previously. Onions don’t like too much nitrogen, but they do like a soil that is full or organic matter, so work in lots of compost before planting.
Depth & space:
Sprinkle seeds gently onto the soil and cover lightly. Sow seeds every 4 weeks to prolong the harvest. Once they are established, they will need to be thinned according to the spacing guidelines found on the seed packet. Alternatively, let them grow a little bigger before thinning and then used the plants you remove as spring onions.
Different varieties may have slightly different planting times depending on their daylight requirements and whether they are early or late varieties. Check the seed packet before planting to see when specific varieties need to be planted.
Care: When planting seedlings out, add a small amount of organic bone-meal to each hole. Bone-meal gives seedlings a great start and helps them to develop strong root systems which support a healthy plant. Don’t worry if your seedlings look a little sad and flop over after being planted out. Just keep them well watered and they’ll be standing up happily in a day or two.
Weed well between the onions. They don't like to compete for food and water.
When the seedlings are young, water regularly. Once they start nearing maturity, allow the soil to dry out between watering sessions. Your onions should reach this stage at some point in spring or summer (depending on the variety and when they were planted). At this point, the rains should be starting to let up, which will make it easier to control how much water they receive.
You don’t want to overfeed onions. Too much nitrogen will cause them to have lovely big leaves and underdeveloped root bulbs. Feed every three months with an organic low-nitrogen fertilizer.
Don’t mulch onions. Towards the end of their growing season, the soil needs to be allowed to dry out or they may rot.
Harvest 25-34 weeks. You will know onions are ready to be harvested for storage when the leaves dry out and fall over. Gently dig the bulbs up and remove them from the soil. Leave them in a sunny, well-ventilated spot to cure for up to two weeks. They’re finished curing once the skin is papery, and the roots and leaves are dry. Once they are cured, brush the dirt off them and remove the dead stems, leaves and roots. Alternatively, keep the leaves on and plait them to hang for storage. Onions should be stored in a cool, dry, well ventilated spot and kept away from direct sunlight. Don’t store any onions that are damaged or mouldy, rather use them up first before they spoil.
Troubleshooting:
• Plants produce many leaves but no bulbs. Planting time incorrect or temperatures are too warm. Bulbing onion and garlic must be exposed to temperatures of 32° to 50°F for 1 to 2 months before planting to induce bulb formation. Place garlic cloves in the refrigerator for 4 weeks before planting or plant early in season so that cloves are chilled.
• Plants are stunted; worms boring into roots. Wireworms are the soil-dwelling larvae of click beetles; they look like wirey-jointed worms. Check soil before planting; flood the soil if wireworms are present. Remove infested plants and surrounding soil. Keep the garden clean and free of plant debris.
• Leaves turn silvery and white streaked or blotchy; leaves may become distorted. Onion thrips are most common during dry warm, weather. Keep the garden clean. Blast thrips with water to wash them away. Use insecticidal soap.
• Leaves die back from tips; root turn pink to red to yellow; yields is reduced. Pink root is a soilborne fungus. Plant in well-drained soil; rotate crops to reduce disease in soil. Plant resistant varieties: Sweet Spanish, Excel, Granex.
• Leaves have yellow or white spots; stalks wilt, bend and die. Gray to purple mold forms on leaves. Downy mildew is a fungus that attacks during wet, humid weather. Remove and destroy old plants debris. Keep the soil well drained. Allow plants to dry out between irrigations. Keep the air circulating in the garden. Plant resistant varieties.
• Leaves fade, wilt, and yellow; leaf tips turn brown. Tunnels and cavities in bulb; plant may die. Onion maggot is a white legless larva of an adult fly. Destroy disfigured plants after harvest. Destroy flies during the growing season.
• Leaves yellow and wilt; leaf tips die back. Seedlings thicken and become deformed. Older plants are stunted limp; bulbs are swollen at the base. Stem and bulb pest nematodes are microscopic wormlike animals that live in the water that coats soil particles; they enter plant roots and secrete a toxic substance. Do not plant garlic or onions in areas where onions, garlic, leeks or chives grew in previous years; parsley and celery are also hosts. Remove and destroy infested plants immediately. Use certified seed.
• Onion necks are thick; plant growth is stunted. Phosphorus or potassium deficiency is likely. Side dress plants with compost tea or aged compost.
• Neck of bulb becomes spongy and water-soaked and gray or brown mold develops. Botrytis rot or neck rot is a fungal disease. Remove and destroy infected plants. Keep weeds out of garden where fungal spores may harbor.
• Onions set flower and go to seed; bulbs are hollow. Nip off flower stalks and flowers so that plant will put energy and nutrients into bulb formation not seed production.
• Bulbs are small but look white and normal. Wrong variety planted or seed or plants planted at the wrong time. Plant a variety suited for your region at the proper time. Keep garden free of weeds; onion family members do not compete well with weeds.
• Leaves yellow, bulbs have soft, watery rot and decay; bulbs may be speckled black. Bulb rot also called white rot is a soilborne fungal disease. Remove and destroy infected plants. Rotate crops. Keep weeds out of garden where fungal spores may harbor. Plant resistant varieties: Elba, Globe, Grandee, Hickory.
• Onion bulbs split into two or three sections. Watering is uneven. Water so that soil is fully moist and then allow the soil to dry to 4 inches deep before watering again. Mulch to keep soil evenly moist. Stop feeding plants 7 weeks before harvest.
• Flavor of sweet onions is pungent. Heat stress and water stress can cause onions to become pungent flavored. Sweet onions are best grown in cool weather with even watering.
• Elongated blisters and streaks on seedlings and bulb scales. Smut is a fungal disease that resulting in dark, slightly thickened areas on leaves. Black lesions appear on the scales of forming onion bulbs. Remove and destroy infected plants. Plant resistant varieties: Evergreen Bunching, White Welch, Winterbeck.
Varieties
1 Yellow
2 Red
3 White
When to plant: September - February
How to plant:
Spring onions are easy to grow from seed and will grow in any fertile, well-drained soil, in full sun. For a continual harvest of spring onions in summer, sow at three-week intervals from September to February. To grow spring onions indoors over winter, sow in March and harvest in spring.
Prepare the soil in autumn for spring sowing by clearing any weeds and dig in soil improver or manure to improve drainage.
A couple of weeks before sowing, rake in some slow or controlled release fertiliser for vegetables. Tread the soil down and rake it smooth, so that the surface has a fine, crumbly texture.
Depth & space: Using a stick, the tip of a trowel or the corner of a rake head, draw shallow channels (known as drills) in the ground 0.5cm deep and 15cm apart.
Sow the spring onion seeds thinly in the drills and cover over with soil. Sow new seeds every three weeks for a continual supply through summer.
Care: Water during dry periods, and water container-grown spring onions regularly to keep the soil or potting mix moist. Don't over-water, as this could leave the plants prone to diseases like downy mildew.
Keep the patch weed free by hand weeding regularly. Spring onions have shallow roots which could be damaged by hoeing.
Harvest: Ready to harvest around eight weeks after sowing, when the plants are around 15-20cm tall and the bulbs are still small, less than 2.5cm across. Pull the plants up by hand as you need them, using a hand fork or trowel to help if needed.
Troubleshooting:
• Onion white rot is a soil-born fungus that causes leaves to yellow and wilt, and bulbs to rot. Control methods include:
- Avoid planting onions in soil where this has previously been a problem.
- No chemical controls are available.
• Onion downy mildew is a fungal disease that can affect the leaves of spring onions, causing blotches on the leaf surface. In severe cases, leaves shrivel and fall off, and plant growth is stunted. It is more common in wet weather.
- Space plants when planting to ensure good air circulation.
- Remove any affected leaves.
- Water in the morning rather than the evening to reduce humidity around the leaves.
Varieties:
1 Bunching Ishikura - long white stalks but no bulbs at the base.
2 Evergreen
3 Trident – mild flavour and grows well in full sun.
When to plant: xxxx
How to plant: Start the seedlings
Depth & space:
Care
Harvest xx
Troubleshooting: xx
Varieties xx