May Seasonal Gardening Tips

May is a prime planting month for autumn and winter crops. We only have short seasons during autumn (April/May) and winter (June/July), so make the most of them. 

That means getting your timing right and being prepared to plant while pest activity has slowed down due to cooler temperatures and lower humidity. Sow little and often (succession planting) for a continuous harvest of fresh ingredients.

Lawns and pruning

The lawn may not be growing as fast as in summer, but make the most of grass clippings by using them as mulch or adding them to your compost. 

Plenty of plants need a ‘haircut’, including woody perennials, lemongrass and bushy shrubs. 

Prune to encourage new growth and shape your plants. Use prunings in compost to build healthy soil, ‘chop and drop’ as free mulch or strike cuttings. Leaves from deciduous trees and blossoms also make a wonderful leaf mould. Bag up and add moisture to create a nutrient-rich soil conditioner, once broken down.

Compost

May is an ideal time to make compost and feed up your worm farm to ensure you have plenty of nutrient-rich soil and potting mix for growing autumn and winter crops in the next six months. 

Beneficial microorganisms are more active in moist soil than when it is dry. So instead of ‘making hay while the sun shines’ why not ‘make compost after rain’? The basis for a healthy garden is organic matter converted into nutrient-rich soil, so use every resource from your garden (or your neighbour’s) to recycle the nutrients.

Container gardens likely need a top-up of fresh potting mix before new plantings. Follow my potting mix guide to improve bagged potting mix or make your own with easily available ingredients for a long-lasting, moisture and nutrient-holding soil. Lifeless, dry dead dirt won’t grow healthy produce, so invest in your health by focusing on your soil first.

What to Plant in May

Pumpkins and sweet potatoes are starchy tummy-filling vegetables that should be ready to harvest. Passionfruit vines should be producing well along with citrus fruits.  

For leafy greens, sow perpetual spinach, chard, silverbeet, Asian greens like tatsoi, celery, lettuce, coriander and rocket. Most of these can also be enjoyed as microgreens along with broccoli, radish, peas, mustard, sunflower and beetroot. 

If you’re not sure when each of our five seasons starts and ends, or what to plant each month, refer to the perpetual Subtropical Planting Guide.

This is prime time for sowing asparagus crowns, beans, all brassicas (broccoli, kale, rocket, cauliflower, cabbages), broad beans, capsicum, carrots, chia, cool season green manures, cucumber (my favourites are cucamelons which are highly productive and require far less water), eggplant, garlic, leek, peas, potato, radish, spring onions, sweet potato and tomatoes.

If you are impatient for peas and beans, sow dwarf/bush varieties first, then climbers. The bush peas and beans will produce flowers and pods earlier than climbing varieties because these need to put on more leaf growth before flowering. The dwarfs will give you a quick crop and 3-4 harvests. 

By then, your climbers will be producing plenty of peas and beans and will last much longer, so you can extend the harvest. A simple strategy for enjoying these vegetables for longer. Sow some peas as microgreens for crunchy pea shoots.

Save your seeds

If you’re not already, it’s important to start saving your own seeds. True sustainability comes from providing for your own needs, so harvest what you can from summer crops.

Dry any herb or vegetable seeds from your garden. Follow this Seed Saving Guide to learn how. You can also grow many plants for free by taking cuttings, dividing clumping plants and other easy propagation techniques. Learn these skills by following the Plant Propagating Guide reference chart.

If you have a tight garden budget, watch this video I created to help you learn how to grow food for free from kitchen ‘waste.’ The tips are so easy to apply and sustainable.

Fruits

Try planting fruit trees such as Citrus, Black Sapote, Carambola, Coffee, Feijoa, Fig, Finger lime, Guava, Kiwifruit, Macadamia, Mango, Mulberry (easy from cuttings taken in the new moon phase), Olive, Passionfruit, Pawpaw, Peach (try tropical and dwarf varieties), Pecan, Persimmon, Pomegranate and Strawberry runners. 

Remember to remove any buds from young fruit trees so they can put energy into growing roots, not fruit.

If your ‘mother’ strawberry plants are throwing runners, separate them and feed up well with compost and liquid seaweed to boost new root and shoot growth. Time to sow new strawberry plants now too!

Herbs and flowers

Some herbs hate the heat – take annual Coriander and Dill for example. However, they thrive at this time of year and will produce hundreds of free seeds for microgreens and next season when they finish later in the year. 

• Sow Borage, Chervil, Comfrey roots, Fennel, Lemongrass, Parsley, Pineapple Sage (easy from cuttings) and Sorrel. 
• There are many easy ways to use herbs . 
• Plant your bulbs and flowers, including Calendula, Cornflower, Daylily, Dianthus, Marigold, Nasturtium , Pansy, Poppy, Snapdragon, Sweet Pea and Viola. 
• Interplant your herbs and flowers between vegetables (particularly brassicas) to attract beneficial predator insects to keep caterpillars and other insects in balance.

Issues to watch out for:

• Fruit fly is a threat we all live with. Unfortunately, if we get mild temperatures, we could expect them earlier this year, with more generations recurring over the coming months. Put your traps in place to minimise damage and control the life cycle. Other strategies that may help are to 1) select early fruiting trees, to miss the fruit fly attack; 2) grow dwarf varieties or keep fruit trees small; 3) cover with suitable exclusion netting.
• Plant a sacrificial crop of Nasturtiums to attract the Cabbage White Butterfly ( Pieris rapae ), Cabbage Moth ( Mamestra brassicae ) and Diamondback Moth ( Plutella xylostella ) to lay eggs on these plants instead of your brassicas (cabbage family). This makes it easy to squish caterpillars in one spot instead of all over your garden.
  
  Try interplanting them around your cabbage family crops. Grow Land Cress  ( Barbarea vulgaris ) or  American Upland Cress  ( Barbarea verna ) as ‘dead-end trap crops’ for the Diamondback Moth and Cabbage Moth caterpillars. The Cress leaves release compounds (glucosinates) that attract the moths to lay eggs. They contain saponins (a natural insecticide) that the baby caterpillars can't digest after hatching.
  
  The tiny caterpillars die, ending the life cycle. When in flower in the second year, Land Cress blooms attract beneficial parasitic wasps that target Diamondback Moth caterpillars. An added benefit! Decoys, exclusion nets, cloches for young seedlings , interplanting and other organic controls can help you manage these pests.

Garden Tasks this Month

• if you haven’t yet fertilised your fruit trees, especially your citrus, now’s the time!
• weed and mulch around fruit trees at the same time. Comfrey and arrowroot are ideal nutrient and moisture-rich mulches.
• stone fruit like tropical peaches and nectarines start flowering, so will benefit from a liquid feed of seaweed, compost tea or diluted worm casting leachate. Moisture is essential during flowering and fruit set.
• keep moisture in the soil by topping up with a layer of mulch. This will help feed the soil, encourage an active microbial community and insulate the temperature.
• harvest any basil for pesto before it dies back and collect the seeds for saving . Grow perennial basil all year.
• cut back arrowroot and perennials. Use the nitrogen-rich material to make compost .
• keep garlic , potatoes and asparagus well weeded. They hate competition.
• this is a prime growing time for all leafy greens without having to compete with grasshoppers. Keep up liquid feeds for an abundant harvest. Add to green smoothies, juices, stir-fries and soups. Harvest early in the morning for maximum moisture in the leaves.