Growing salad greens
Top hints for growing salad greens
- use seed that is less than a year old
- germinate in the light
- keep seed well watered until rooted
- grow in well prepared soil containing compost and nitrogen.
What are salad greens?
Salad greens include hearting, butterheads, cos and loose leaf lettuces, corn salad, rocket, arugula (wild rocket) and wasabi rocket, mustard, cress and watercress, green and purple mizuna, radicchio, endive, baby spinach and baby silverbeet, and other exotic leafy greens. Some of these, along with sunflower, kale and peas, can be grown as microgreens. Add in herbs and edible flowers to create salads with a great range of colours, textures, and flavours.
Lettuce seed is only viable for a year, losing its viability quickly after that. It also needs to be germinated in the light and kept really moist. Any drying out will kill the seed. Spread seed onto a firmed, watered seed bed, press the seed onto the surface, and check everyday that it is still moist. Water well if not until the seed has germinated and is rooting into the soil bed. After this, keep the seedlings damp but not wet. When transplanting seedlings, water in with Maxicrop or Seasol to reduce shock.
Salad greens prefer warm days and cool evenings, and should therefore be grown in partial shade in summer but in partial sun in spring and autumn. Lettuce germinates best at temperatures around 21ºC but poorly below 10ºC and above 26ºC. Plant year round. Salad greens are tastiest if grown quickly.
Salad greens grow in any good, well drained soil but the soil should also be capable of retaining moisture. Dig the soil over so it is loose and weed free, and incorporate compost, nitrogen (eg poultry manure) and potash (potassium) in the top layer for best results. The pH should be in the range 6 – 6.8.
Planting and spacing
Lettuces and other salad greens can be sown directly or in punnets. If sown directly, they will need thinning. Spacing for lettuce depends on the variety, and can vary from 10 cm – 45 cm so follow the instructions on the seed packet. For other salad greens, also follow the instructions on the seed packet. Some such as mizuna grow tall and wide (and one plant is sufficient) while others are more contained. All salad greens may need thinning but use the thinnings in your salads. Some lettuces are called ‘cut and come again’, meaning that you can harvest the outer leaves while leaving the central growing tip in place. Succession plant salad greens every few weeks.
As lettuces are shallow rooted, they need regular watering or they will become tough and bitter. Water regularly every second day in summer and keep moist at all times to prevent bolting. Other salad greens benefit from this regime.
Lettuces are heavy feeders. Spray with 1/2 strength Maxicrop or Seasol if necessary every 2 weeks but be aware that producing soft leaf brings hordes of snails and slugs so you can skip this if your soil is well prepared as above.
Pest and diseases
Snails, slugs, earwigs and caterpillars are the main visitors. Necrotic yellow virus which is transmitted by aphids from milk thistles will kill lettuces. It is vital to weed out milk thistles for a considerable distance around lettuces, including ‘the other side of the fence’, on the nature strip, or any weedy area.
Written by Robin Gale-Baker