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June gardening is always marked by berries. The June-bearing strawberries, oso berries, and currants are ripe and ready to be picked. The first raspberry flush will come any time, and the fruit on the earliest blueberry bushes start to turn blue. With the tulips, peonies, and irises completing their bloom cycle, we are fully in summer. Everything you haven’t planted yet should go in the ground, while we maintain and nurture the plants we have already established.
Pruning
As soon as your lilacs have stopped blooming, you should consider pruning them back so you might get a second bloom this fall. You want to take as much as ⅓ of the plants stems, so you encourage new growth each year. This is the case for all your early summer blooming shrubs and trees, like azalea, forsythia, Japanese kerria, weigela, deutzia, mock orange, St. John’s wort, viburnums, and red or yellow dogwoods.
The pruning should extend to your tomatoes, now established in the ground. You’ll want to prune for suckers, depending on what kind of trellis system you have set up. If you’re allowing indeterminate tomatoes to only have one strong “leader” or stem, prune aggressively, but you’ll need tall trellises. Also be sure to cut away any diseased parts of the plant, but remember you only want to touch your tomatoes after the morning dew has dried, and with clean shears. Spray with Lysol or other disinfectant in between plants, so you are not spreading fungus or virus yourself.
Once the strawberries are done fruiting, mow them back and mulch them, so they won’t continue to spend their energy growing runners, but will focus on root growth for next year.
Fruit-thinning
Your pears, apples, stone fruit like peaches and nectarines, and even fig trees will have set fruit by now, and also gone through fruit drop, which is a normal phenomenon where the trees drop what they can’t handle. With the fruit still on the tree, you must decide on quantity or quality. Thinning the fruit on each branch will allow the tree to create larger, tastier fruit. You can also shroud the fruit at this point, covering the fruit with gauze bags, to protect it from invasive bugs or animals.
Fertilizing
It’s important to not simply water your vegetables in raised beds, but remember to feed them. Your plants can benefit from a treatment like fish fertilizer as much as once a week, but if you haven’t fed your vegetables since planting, June is the time to start. Apply a vegetable-specific fertilizer, which will generally be a balanced 4-4-4 fertilizer at least once or twice a month. Your tomatoes can also benefit from a treatment of Cal-Mag or Rot Stop, which will provide the plant more calcium to help prevent tomato blossom rot on forthcoming fruit. Now that your asparagus has been harvested, apply a nitrogen-heavy fertilizer for next year.
Your lawn should get a low-nitrogen based fertilizer in June. Your roses should get a phosphorus based fertilizer treatment after their first bloom, about now. All your trees and shrubs should get a summer fertilizer before July 4th. Your garden center can help you find the right fertilizers, since not all plants should get the same one. For instance, blueberries and azaleas need a more acidic fertilizer.
Pests
June is high alert for all the bugs and critters that love to find and attack our plants. Tomato hornworms, aphids, bagworms, beetles, borers, and all the slugs. Sprays won’t be the only solution at this point—you’ll need to manually remove the pests from your plant as well. Aphids may be sprayed off with water, but without a treatment like soapy water or a nearby trap plant like nasturtiums, they’ll be back. If you don’t have nasturtiums nearby, plant them now. The aphids will be more attracted to the nasturtium and will choose it instead. You just leave the aphid infested nasturtiums in place. Treatments like Sluggo can help reduce the slug population, but manual extraction is still necessary. Leave shallow lids of beer or yeasty bread starter around as a trap, and collect the slugs that run to it each day. Each plant in your garden has a number of pests that are trying to feed off of it; a daily walk around your garden will help you notice what might be attacking your plants.
Sick plants
Gardens are highly susceptible to virus and fungus, and one of the best ways to prevent it is to water at the root of plants, rather than overhead, which splashes onto the ground, causing water to spray back up onto plants. As you see blight or mosaic virus in your garden, you must be vigilant to cut it out quickly, dispose of those plants in the trash (not compost) and be sure you wash your hands and tools before moving onto the next plant. If you see powdery mildew on your plants, you can treat it with a diluted vinegar spray. Now is when you might catch sign of infections like leaf curl on your stone fruit trees, which can be treated if caught quite early with copper foliar sprays. Fungicides can go a long way to helping prevent problems like black spot on roses. You want to be very judicious when using fungicides and copper sprays, these are mostly preventative treatments, not reactive. If you’re questioning what you see in your garden, take a picture and head to the garden center to ask.
Planting
The summer vegetables should all be in the ground by the end of June. Your tomatoes, eggplants, peppers, and tomatillos need to be planted, and if the weather hasn’t met planting conditions yet, you need to consider putting mitigations like Argibon in place and planting anyway. The Agribon tenting will create the warm conditions you need, and you can remove it when temperatures get warm enough on their own.
Beans, cucumbers, edamame, eggplants, melons, okra, summer squash, and sweet potatoes should get planted this month. If it’s early enough, they can still be direct seeded, but by mid-June, you should plant starts instead.
Continue succession-seeding radishes, lettuce, carrots, scallions, and beets. Be sure you are thinning seedlings once a week.
Flowers
You can still plant almost all your summer annual flowers, including zinnias, cosmos, sunflowers, salvia, and celosia from seed or as starts. Planting them in waves ensures multiple successions of flowers later in the season. Remember when planting these flowers to check seed labels for heights, so you can vary them.
Now that your spring flowers are wilting, deadhead them appropriately. Your tulips need to have just the heads cut off, but no lower—remember they need leaves to mulch in place to return next year. Iris stems may be cut to the ground, but in a chevron, to ensure good growth next year. Deadheading your snapdragons and sweet peas will encourage more growth, but some flowers, like stock, are single -stems, so once they bloom, they should be cut to the ground.
Through June, the best course of action is to take a walk through the garden once a day, even if it’s a quick one. Harvest what you can, take note of action items like pests or pruning, and be sure to take pictures and write entries in your garden journal. Moreover, it’s the reason you planted the garden: to enjoy it.
