Root of the issue

DURING my years working at Harlow Carr, I have regularly overheard people in the kitchen garden exchanging stories about the difficulties of growing carrots.

Although sometimes problematic, if certain conditions are met correctly, carrots can be relatively easy to grow. The starting point for getting it right is the soil. Carrots will grow best on an open, sunny site. The soil should be dry and light, free from stones and not compacted. Well-rotted manure or rich compost is beneficial if added to the soil during the previous autumn so that concentrated nutrients can leach out. If too much nitrogen is present, the carrots will put on more leaf growth than root. A raised bed works well by giving the carrots a good root run and leaf mulch forked into the soil in autumn is beneficial as it is slightly acidic and carrots grow best between 6 and 6.5 pH.

From short, stubby white varieties to large, conical purple ones, there is now a whole world of carrot diversity to choose from. This can all seem a bit overwhelming at first; however, choice can be narrowed down significantly, and should be determined by how long you want your carrots to grow for.

Carrots can be classified into two main categories: early and maincrop. Early varieties are sown in spring and can be ready from seven weeks after sowing; maincrop varieties are sown from late spring to early summer and can be ready from ten to 11 weeks after sowing. Maincrop varieties tend to be larger and longer and store better.

Carrots are best sown directly into the ground as they do not transplant well. Sow thinly in rows 15-20cm apart, 1-2cm deep. Alternatively, carrots can be sown in deep pots by scattering the seeds then thinning out later on. Although the site should be dry, carrot seeds won’t germinate without moisture, therefore watering every day may be necessary until they emerge. If temperatures fall below 7C carrot seeds may not germinate at all so using a cloche as protection can be beneficial. If temperatures are in excess of 20C, seedlings may only take a week to appear.

Thinning is required so that carrots do not become stunted and slender. Initially thin to 5cm apart which can then be increased, depending on the carrot variety you have. If carrot seedlings are really close together, don’t thin by pulling them out as you may damage the carrots left behind. Instead, cut the foliage off with scissors. This method will also limit the spread of carrot scent that attracts the notorious pest: the carrot fly. If thinning by pulling them up, do this on a still day or in the evening to avoid the scent attracting the carrot fly. It’s also advisable to postpone this until the carrots are at least 5cm high so that the thinned out carrots are edible; perfect in salads.

Carrot roots do not like temperatures above 2C. Prolonged warmth above this will create small and bland carrots. Mulching the soil with grass clippings in summer will help keep the ground cooler and will also help reduce the likelihood of carrot fly by creating a physical barrier, masking the scent of carrots and encouraging predatory insects such as earwigs.

If you’ve grown carrots before you’ve probably come across carrot root fly. Female flies are attracted to the carrots by their scent and lay their eggs in the soil next to the carrots. The emerging white maggots tunnel into the carrots and begin eating them, causing them to rot and destroy entire crops. The only real prevention available to the amateur gardener is a physical mesh barrier. Aphids and slugs may also cause problems so be vigilant.

Some good early carrot varieties to try include Nantes Express, Parmex and Nairobi. Maincrop varieties include Autumn King, Chantenay Red Cored Favourite and Narman. Some quirky varieties to try include Purple Haze and White Satin.

Jobs to do this week

• Regularly water containers

• Finish planting out all tender crops such as courgettes and sweetcorn

• Switch from growing spinach to chard as chard is less prone to bolting in the heat

• Keep on top of emerging weeds amongst the veg plot

• Regularly check stoned fruit for water as the roots are shallow

• Pinch out side-shoots from cordon tomatoes regularly

• Tie in sweet peas

With thanks to Francesco Ponziani, Horticulturist at RHS Garden Harlow Carr

For more information on things to do in the garden this month visit rhs.org.uk

DIARY DATES

July 9, 16 and 23: Lazy Summer Evenings

Visitors can enjoy the beauty of Harlow Carr as dusk settles on three Thursday evenings throughout July. Bring a picnic and a bottle of wine or treat yourself at Bettys Tea House in the garden. There will be live music on the lower lawn from 6 – 8pm. Last entry is 7.30pm and the garden closes at 9pm. Members can bring two guests free of charge and non-members pay half-price admission after 5pm.

July 11 and 12, 10am – 4pm: The National Sweet Pea Show

Top Sweet Pea growers from up and down the country enter this prestigious weekend-long national competition which promises visitors the sights and breathtaking scents of what can only be imagined from hundreds of vases filled with Sweet Pea blooms. Members of the National Sweet Pea Society will be on hand to offer expert advice, and bunches of their beautiful surplus blooms will be on sale. Normal garden admission.