Your first Summer
Crops
Spring is a wrap and it's time now for new stock at Pierre’s and new kinds of fish and forage! Check your field size and cash on hand and make your shopping list. Buy a little of everything, but since your field is now at the limit of what you can manage, focus mostly on Melons (which give you the most for your time and energy), maybe some extra Hops for food and Pale Ale (though it is an inconvenient trellis crop), plenty of Blueberries for cheap (compared to Melons) gifts, and maybe extra flowers for the same. Through the month, as you are able to get more sprinklers or an upgraded can, you can grow and diversify more--limited again by the time and energy cost of planting and harvesting anything but the slowest, most valuable crops. Keep focusing mostly on Melons.
The last few days of summer (specifically, 24-26) is actually quite a good time to plant some wheat. It survives into Fall (as does Corn, but that’s most profitable if planted earlier in Summer) and ripens in only 4 days. So any soil under Wheat is still hoed, and even still fertilized (normally the fertilizer disappears at season change), and you should still be able to get two Pumpkin crops through before Winter. (If you plant wheat on day 27 or 28 this won’t quite work. There’ll still be time for other crops.)
Artisan
A big new focus this month is on processing your produce in Preserves Jars and Kegs. Preserves Jars are very easy for you to make at this point. And they have a high rate of return for fruit and vegetables. Kegs are slower for Fruit and Vegetables, but next year, their products can be aged in Casks. For now, they can turn Hops into Pale Ale very quickly, taking about 1.5 days to go from a 25gp crop to a 300gp artisan good, and this is an unusually good rate of return on both money and time. Wheat into Beer is just as fast but the output is not quite as profitable.
For Kegs, you need copper, iron, wood, and oak resin - it’s a good time to keep Tapping Oak Trees. You might even plant some oak trees in a nice line out of sight with one nearby as an alert. When the nearest has syrup, you’ll know to collect from all of them. Keep tapping lots of Oak Trees and planting groves around the valley (anywhere you can till; even the Beach works) so you develop plenty of Oak Resin and can eventually move your Tappers off your farm.
Craft Preserves Jars and Kegs to start earning big farm profits; wines and juices are very profitable. Of the two, Preserves Jars always have the highest rate of return for fruits and vegetables due to their faster speed, so they are good for your first year even though Kegs have higher profit. Later when you are even richer and lazier, you will want to put your crops in Kegs and forget about them, then put your Wines into Casks for a month. But for now, keep your income flowing mostly with Preserves Jars and a few Kegs.
Keep your Jars, Kegs, and Chests in a barn. Your buildings are all bigger inside than outside, and barns scale the most. Or keep them in a shed for good looks. Either way, the nice thing is you can rearrange your farm any time without disturbing them. Put one Jar and one Keg in plain sight and fill it last as an alert for when the others are ready.
Story
Three days into Summer, an earthquake will open up a new area. This is the train station and Spa area to the north of Robin’s house. As in Spring, you’re probably working til you’re nearly exhausted. The Spa is refreshing! Once you’ve run low on energy, you can go and soak in the pool for 20-30 minutes - sit *still* - and your energy bar will refill. The shortest way to the Spa is via the Backwoods - in other words, the northern exit to your farm. After you’ve had a soak, you probably have the energy to chop wood or go fishing, and sometimes you’ll have the time to go mining. It may be worth doing this every day!
Tool upgrades
If don't yet foresee your sprinklers covering most of your watering soon, consider upgrading your watering can when rain is predicted. The day before the rain, take your watering can to Clint for an upgrade before 4:00 p.m. and pick it up after 9:00 the morning after the rain. On the rainy day, mining with lots of food on hand, especially if your TV luck is good, or fish for hours until you catch enough easy fish to level up (see complete walkthrough on Spring 2). Any day you finish your chores early, go fishing or go back and mine a previous good floor for ore even if you can't advance another 5 floors. Iron is very useful in your first summer, it is needed for crafting several highly desirable things, including sprinklers and kegs; you’d also like to upgrade your watering can, then your axe and your pickaxe. For that you have to get past floor 40.
If you can get a steel axe before the end of summer, you can cut your way into the Secret Woods and find some Fiddlehead Fern; otherwise you will have to wait until next summer for Fiddlehead. (You can’t complete the Bulletin Board bundles before Summer of year 2 anyway, because Red Cabbage seeds aren’t available until then, so don’t get too upset if you miss this one in your first year.)
Steel axes also let you get Hardwood, which is initially useful for crafting the Cheese Press. If you can afford a Barn and some Cows before the end of summer, cheese sells for nearly twice as much as milk. If you haven’t got a Coop, you probably want that before the barn.
Animals
Use the hopper in your Coop or Barn to withdraw hay from your Silo. You can't withdraw when your feeding bench is full. If it is, wait for a rainy day. You’ll want 10 for the Community Centre, and if you stow the rest in a chest and then you can cut more without paying for a second silo.
Fishing
Try to go fishing in a few different times and places - if you’re serious about the Fish Tank bundles, make a list of the fish you need, and consult a reference to find out which ones you can catch in Summer and what the conditions need to be.
Lightning rods
It’s good if you can put together one or two lightning rods by late summer - these will yield batteries the day after a thunderstorm, and a few batteries may let you craft iridium sprinklers for the Greenhouse in winter. This is not the only way to water the greenhouse, of course, just the easiest. They will also protect your farm from lightning.