Gardening: What to plant in September

One of the biggest mistakes a gardener can make in spring is planting seeds too deeply. Photo / Getty Images

Spring is the time to lay the foundations in the garden to ensure a blooming good summer.

Daylight hours are getting longer, and there is a hint of warmth in the air. Spring is here.

This time of the year can be the most unpredictable though, with driving rain and frosts one day and hot sunny days the next.

It is a great time to get summer seeds sown, and while some areas may be still be too cold to plant directly into the garden, it is a perfect time to get seedlings established in pots on a sunny window sill or greenhouse - if you are lucky enough to have one.

Remember that when raising plants from seeds, the biggest error is planting them too deeply in the soil. A good rule of thumb is to cover with soil to a depth of the seeds' width. With tiny seeds you need only sprinkle some fine soil over the top and press down. Keep the soil damp, but not sodden.

I cover my trays with a pane of glass to keep the heat and moisture in. You could try using clear wrap from the kitchen if your potting shed is your window sill.

It is also a great time to make liquid manure. This can be sprinkled over pot plants and garden plants as an instant energy boost.

A good tip is to visit your local beach after a good storm and collect a sack of seaweed. Back home, place this in a large drum or bucket, cover with water, and then secure your 'witches' brew' with a lid. Some people advise washing the seaweed first, but I never do.

After a couple of weeks you will have a wonderful liquid seaweed manure to treat your plants. Dilute the mixture in a watering can with tap water so it looks like weak tea. Sprinkle over the foliage of your plants to produce quick healthy growth.

Urban orchard

Your peach and other stone fruit trees will have likely burst into blossom by now. It is important at this time to encourage pollinators onto the blossom.

If there are not a lot of bees around you can try attracting them by spraying a white sugar and water solution onto the blossom. Do not use honey as this can spread diseases to bees.

Peach leaf curl is a disease caused by a fungus called Taphrina deformans. It can affect blossoms, fruit, leaves and young shoots of peaches, ornamental flowering peaches, and nectarines. It is a very common disease that backyard gardeners have to contend with. The most obvious symptoms are distorted, twisted and red young leaves in spring.

A spray with either copper or lime is the best treatment, but timing is everything. Spraying in early winter, when the tree has lost all its leaves, and then again just before the buds start swelling, getting ready to open with blossom, in early spring.

Citrus trees need a good feed now. They are 'gross feeders' (that sounds like my family around the table). But it means they need regular and generous feeding throughout the year. Spread some compost, aged animal manure or even your spent seaweed from your liquid fertiliser around their base.

Vegetable seedlings to plant now

• Broccoli
• Lettuce
• Spring onions
• Leeks
• Peas
• Seed potatoes
• Beetroot
• Carrots
• Kumera (in frost free areas)
• Tomatoes (in frost free areas)
• Bok choy

Seeds to sow in trays inside

• Tomato
• Capsicum
• Chilli
• Lettuce
• Brassicas
• Pumpkin and squash
• Spinach and silverbeet

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