If slugs and snails have decimated your hostas, it is possible to cut the foliage off, feed and water them well and they will spring into fresh growth which you can resolve to keep free from munching critters. This approach only works when plants are still in full growth and is the principle behind cutting back hybrid clematis which have finished flowering and roses past their first flush.
Containers of gross feeding annuals or perennials need liquid feeding, preferably weekly, and watering on a daily regime. Hanging baskets which are crammed with overcrowded flowering plants to gain effect may need twice daily watering as well as weekly liquid feeding to keep them looking good. These flowering plants are putting so much energy into putting on a display that they need the horticultural equivalent of the energy drink to keep them going. Deadheading will extend the display.
Containers planted with shrubs usually just need watering regularly because they should be getting their sustenance from slow release fertiliser in the potting mix and shrubs are more vulnerable to fertiliser burn from over feeding.
Stay on top of the weeding. Vigilance is the key to stopping an explosion of weeds.
Spray for thrips on rhododendrons if you have a problem with silver leaves. Fresh infestations can be seen on the underside of the foliage. Adult thrips are black and new ones are white.
Flowering cherries are one tree that gets pruned in summer, not when dormant in winter. So if you need to prune cherries or to take out witches broom (identifiable as strong growing, very leafy branches which fail to flower) plan on doing it over the next month or so.
In the vegetable garden, January is traditionally the time to plant out for winter although it may be a tad early for us. Some of the cabbages might be ready before winter if you put them in now. Winter vegetables do their growing in summer and autumn and then hold in the garden for you to harvest in the colder months. The key is to get the timing right so that they do not go to seed before winter.
Harvest garlic. It can be lifted now even if it is still green, and left to lie on the ground while the foliage dies off. Not so onions. Leave them until the tops are bent over.
Keep successional sowings of sweetcorn and other summer crops going. You have until the end of this month to ensure they get through before cold weather strikes. Although some of us might be wondering whether warm weather will ever actually arrive this summer.