Citrus in pots can be put outdoors in summer, in a sheltered sunny position, but only when temperatures increase, from mid-June until late September. Keep some fleece handy in case of sudden cold nights in early summer. Low temperatures will inhibit flowering and may cause damage or even death.
A minimum winter night temperature of 10°C (50°F) is needed for lemons and limes. Citrus are hungry plants and need regular feeding. Use high nitrogen citrus summer feed from late March to October. In winter switch to winter feed that is specific to citrus.