Helpful tips for winter gardening

Dried flower heads of the frost hardy, perennial succulent Sedum matrona last all winter.
Dried flower heads of the frost hardy, perennial succulent Sedum matrona last all winter.

A brief and welcome shower quickly brought autumn leaves tumbling to the ground. Winter is normally here by June but took its time this year. We’ve hardly had a frost and the foliage of deciduous trees and shrubs is changing colour far later than usual. 

The small, maple like leaves of my Lebanese crab apple, Malus trilobata, were dark red in mid-May last year but are still bronze, as are my various smoke bushes (Cotinus). But after yesterday’s shower there are enough leaves on the ground to rake up for mulching flower beds and topping up my weldmesh leaf mould container.

My medlar tree (Mespilus germanica) and Chinese quince (Cydonia sinensis) are laden with fruit so clearly they liked the dry summer. Stonecrops (Sedum sp.) also enjoyed the long stretch of dry weather and as they’re frost hardy, I’ll leave their dried flower heads until August.

June is a good time to remove dead asparagus fronds. Like with flowering bulbs, the leaves above the ground feed the plant beneath so shouldn’t be removed while they are still green.

June is a good time to remove dead asparagus fronds. Like with flowering bulbs, the leaves above the ground feed the plant beneath...

You need to collect all the dead asparagus fern and also any debris around the plants, or you risk the pesky little asparagus beetle overwintering in the stems and causing havoc next spring. 

You can either burn or compost the debris but only compost it if your heaps are alive and kicking, i.e. if you kept them damp and therefore active during summer.

Once the asparagus bed is clean, cover with a thick layer of well-rotted manure – dried cowpats are perfect - as asparagus crowns are greedy feeders. 

Failing cowpats, you can easily make liquid manure from pelleted poultry manure fertiliser. Add one cup of pellets to one (nine litre) bucket of water and leave for a couple of weeks. This makes a strong brew so dilute to the colour of weak tea before distributing it from a watering can.

After fertilising, mulch asparagus thickly as crowns need protection over winter.

Liquid manure is also handy for fertilising summer- and autumn-flowering bulbs including crocus (Sternbergia), autumn snowflake (Leucojum autumnale) and Naked Ladies (Amaryllis) after flowering has finished. 

The leathery evergreen leaves of the scented, winter flowering Iris (I. unguicularis) can be cut back in early June to allow sun into the clumps and encourage more flowers.

This beautiful iris loves a well-drained, sunny corner where it will spread into a vast tangle of half-dead leaves so cutting back now rejuvenates it nicely.

It’s easily increased by dividing and replanting in spring.

Final June job is potting the cuttings I took over summer. This involved a return visit to the leaf mould container, where I was lucky to find actual leaf mould under layers of dried leaves, the perfect potting mix for rooted cuttings.

Do It Now: Spread horticultural fleece (from garden centres) over potentially frost tender plants.