From mid-summer until November, rhododendrons and camellias are forming flower buds for next year’s display, so it’s essential that the compost or soil around them doesn’t dry out at any point, if it does they simply won’t form buds or will demonstrate their disapproval by shedding the ones that have already formed. Check your plants daily – those in pots may need checking twice a day and water, with rain water if possible though hard water is better than nothing in the short term..
The sound of Autumn seed and plant catalogues thudding onto the doormat dropping through the letterbox, is a reminder that it is time to order seeds for autumn and winter vegetables for the greenhouse or polytunnel. Most gardeners use the space to protect tender plants from frost but if you have spare space, don’t discount this option. Just a little protection encourages tender growth and you can continue cropping tasty salads right through winter. Lettuce like ‘Four Seasons’ and ‘Tom Thumb’, any oriental vegetables, including ‘Pak Choi’ and ‘Mizuna’ greens, ‘Lamb’s Lettuce and spinach like ‘Veneto’ and Radicchio are ideal for late summer sowing and will be ready for harvesting from late September onwards.
It’s also time to plant new potatoes for Christmas or earlier. Late season, second crop potatoes, stored in temperature controlled conditions to maintain dormancy are sent out from late July to early August. In warmer areas, plant them outdoors immediately, protecting the foliage with horticultural fleece if frosts are forecast; they will be ready to harvest from late October. In cooler parts of the country where frosts are more common grow them in pots. Stand two or three tubers on a 5in layer of multipurpose compost in a flower pot, at least 12” wide, then cover with a further 4-6” of compost and water well. When the shoots are 6” high almost cover them with another layer of compost, continuing the same process as the stems grow until the shoots are within 2-3” of the top of the container. Move them into the greenhouse before the first frosts; it is a good idea to plant several pots, leaving some to be harvested early and others for Christmas dinner. ‘Carlingford’ and ‘Charlotte’ are two reliable performers. They can also be ‘chitted’ and planted out in late August and Early September.
At this time of year, annual displays are often flagging and a bit of a boost and tidy up. Lightly trim them over then pick through carefully to remove dead or diseased material and treat any pests. If the compost is dry, dunk the basket in a large bucket or the water butt for an hour to allow the water to soak through then feed with a high nitrogen fertilizer to boost re-growth. Once the plants are revitalised, return to using tomato fertiliser for the rest of the season.
Now is a good time of year to use nematodes to treat vine weevil. The nematode Steinernema kraussii is effective when soil and compost temperatures are between 5-20 degrees centigrade.