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Long Island Horticultural Society

What's Going on in the Garden

June To Do List

June is a great month to get out into the garden the temps are still nice to work in and there is a lot of stuff to be done.


Direct sow seeds for annuals outside. If you like color and can embrace a little chaos, sow reseeding flowers, including blue honeywort, forget-me-not, golden feverfew, love-in-a-mist, sunflower, and sweet alyssum. These unfussy, drought-tolerant annuals will cheerily pop up for years to come.

There’s still time to start annual flowers from seed, including cosmos, marigold, nasturtium, sunflower, sweet alyssum, and zinnia. For faster  bloom, buy seedlings. To attract butterflies to your garden, plant aster, buddleja, sweet William, Mexican sunflower (Tithonia rotundifolia), milkweed, and pipevine.

Plant beans, squash, melons, gourds and cucumbers and make trellises for their vines to grow on.

Plant members of the nightshade family outside if you have not already. Remember to plant your tomatoes deeply. Snip off the bottom leaves and plant the whole seedling down under the soil just until the top set of leaves is above the soil level. Those fine hairs on the steam will turn into roots when underneath the soil and you will have a good strong root system for your tomatoes.

Right after you plant out your cucumbers start a new batch of seeds indoors so you can re-plant in July when the cucumbers start to succumb to downy mildew. 

Many normal-size pumpkins need around 110 to 120 days to mature, so you’ll want to start sowing seeds between late May and the first of July. Varieties such as ‘Cinnamon Girl’ and ‘Winter Luxury’ are great choices for pies. For decoration and pies, try ‘Musquee de Provence’. If you’ve never grown pumpkins before, a mini version such as ‘Mini Jack’ is a forgiving and quick-maturing choice.



Use trellises to support vine crops for greater fruit production. Climbers are easier to pick this way and are not as messy, and the crop is less prone to slugs, snails, and ground rot.

Are critters causing trouble in your garden? Try deer- and  rabbit–resistant perennial flowers, including agastache, artemisia, lavender, monarda, ornamental oregano, Russian sage, salvia, and yarrow.

Maintain a 3-inch layer of organic mulch throughout the garden. This prevents crusting and cracking of the soil surface, holds in moisture, encourages earthworms, moderates ground temperature, and prevents weeds from germinating.

After tall-bearded irises stop blooming, cut off spent flower stalks to promote new rhizome growth, apply fertilizer to the soil, and water thoroughly.

Immediately after bloom, prune rhododendrons to control size and shape. Cut each stem back to just above a rosette of leaves. Most varieties of garden-scale rhododendrons aren’t harmed by hard pruning.

Feed potted specimens at least monthly with liquid fertilizer. They need it because increased summer watering washes nutrients out before plants can use them.



Harvest your cool season veggies, like peas, lettuce and radish. Pull all the cool season plants out from their containers, fertilize the container to get ready for the warm season veggies all which are heavy feeders like; tomatoes, peppers, and cucumbers. After planting top dress with mulch and water well to get all the plants off to a good start and get them ready to handle the heat of summer. Mulching container has the same benefit and mulch on the ground, it conserves moisture and prevents weeds.

Establish a twice-weekly harvest schedule to keep herbs and vegetables growing vigorously. Pick pea pods as soon as they’re plump; pull radishes from the ground as they fatten up; and regularly pinch leaves off basil, mint, and parsley.

Handpick strawberries frequently and apply an iron phosphate snail and slug killer if the berries suffer from snail or slug damage.

Help the Bees

Rather than build a fancy honeybee hive for your garden, think about taking care of native bees, such as mason bees, that do much of the crop pollination in the United States. Many native bees use holes in wood or dirt to nest. Consider planting a log in your garden for native bees to live in. Drill different sized holes for the bees to live in.  Also consider mulching differently, using lighter weight materials such as pine needles, leaves, straw as not to inhibit mining bees from nesting in your garden. Heavy bark mulch is just as impenetrable as pavement to these small bees.

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