Solving two problems at once-- Mulch heavily and add compost
Mulch like straw or leaves with high carbon ratio will keep the soil cooler and darker. If your hops are day sensitve -- like Fuggles they come up when the day is long enough no matter what the temps are. Here they emerge at equinox in March and get themselves frost pruned every
single year. But they go on to produce just fine when our nights warm up enough for growth.
Compost and green manures help feed the soil to feed your third year hops. Hops don't need a ton of nitrogen(N) but PK for sure. Compost well made supplies phosphorus and potassium and green manure plants like clover improve drainage as well.
The best resource is from Crannog Ales. http://www.crannogales.com/HopsManual.pdf
All I learned I learned from Rebecca