Added on June 12, 2023 Sara Swanson

June 2023 Gardening Advice

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submitted by Jennifer Fairfield, Garden Mill

Here are some things to do in order to stay at least somewhat ahead of the game this month:

In the veggie garden:

The main thing we all need to be doing right now is watering. Everything. Constantly. That may be a slight exaggeration, but only a slight one. With the unusual lack of rain in May and the high temps we’ve been experiencing lately, our plants need our help to supply them with enough water to keep them alive and thriving.
The cold overnight temps that we were having up until just a week ago made it difficult to get warm-weather veggies and herbs planted, so now we need to play catch-up. If you haven’t gotten your veggies and herbs planted yet, now is the time. We have a short growing season, and many of the things we all love to grow — tomatoes, peppers, eggplant, cucumbers, squash, etc. — all need long growing periods to produce a good crop. So, get them in now. And then water them. And water them some more. Still need seedlings? We’ve got lots of plants available at the store for tomatoes, sweet and hot peppers, eggplant, kale, and all sorts of herbs.
Plant seeds of carrots, bush beans, dill, and cilantro every week or two. This way, you can be sure to have a continuous harvest throughout the season. Be sure to read the package information about how long each variety you are planting needs to mature. Figuring that our first frost usually hits around October 15, you can determine how late you can plant things and still hope to get a good harvest. Once you have planted seeds, be sure to keep the soil around them moist. Seeds won’t generally germinate in dry soil. You can apply a thin layer of mulch to help keep moisture in the soil, but be careful not to put so much mulch over the seeds that the new plant shoots struggle to get through.
For anything that needs support, be sure to get stakes or cages in at the time you plant so that you don’t damage roots later. Be sure to mulch them at the time of planting, too. Mulch does a number of great things for your plants — it keeps the soil temperature consistent, suppresses weeds, helps retain moisture, and helps prevent soil-borne diseases from spreading to your plants.
Spray tomatoes, cucumbers, and squash with an organic fungicide early and often to prevent diseases. Begin as soon as you get the plants in the ground, and follow the manufacturer’s instructions for frequency (usually weekly). Diseases such as blight, powdery mildew, and downy mildew can only be prevented, not cured. Applying fungicide on a weekly basis can help prevent diseases from getting started, as can making sure to space your plants properly. Good airflow through the garden helps things dry out in between rains, which helps keep spores from growing.
Weeding is an important part of keeping your plants healthy and producing, even if it’s not everyone’s favorite chore. Weeds compete for water and nutrients, and they can also be disease carriers. Doing a little weeding every time you’re in the garden can make it seem a little less tedious, and getting weeds before they get too big is so much easier than waiting until they are towering over everything. It’s especially important to pull weeds before they go to seed, so that they aren’t starting a new generation of weeds in your garden. I had a fun (not really) reminder of this recently. For a variety of reasons, I had not been able to get into some of my flower beds to get them cleaned up this spring. I started on that task a week or so ago and found the bed I was working in was a total mess of weeds. It started out with my determination to pull the handful of garlic mustard that I saw — before it went to seed — then I saw some purple deadnettle that needed to come out, and then I found something I have never encountered before, and it was all over. When I reached to pull it, it literally spit its seeds at me! I’m not kidding — I got a face full of seeds every time I got near the plants. I looked it up later, and found that it was hairy bittercress, which I had not gotten to before it went to seed, and which has this crazy thing it does to spread its seed effectively. Whenever something touches it, even a breeze, it throws seeds as much as 3 or more feet away. Because I didn’t get to it before it had formed seeds, I will likely be pulling that stuff for years now. You can bet I won’t let that happen again next year!

June is a time when lots of insects start showing up in gardens. Aphids, flea beetles, cucumber beetles, Colorado potato beetles, cabbage moths, and slugs will be making meals out of your plants this month and into the summer, if left to their own devices. While most healthy, mature plants can withstand some of these, young, tender, new plants can be decimated in no time. The key to keeping them from causing unrecoverable damage is to keep a close eye out for them and get them before there are so many that they overwhelm your plants. Be sure to identify who is doing the damage before you reach for the insecticide though — the right solution depends on the pest. Also be careful when and how you are applying pesticides. Any pesticide that you use has the potential to kill beneficial insects, such as bees and butterflies, so making sure that you are targeting your application to the affected plants (rather than broadly spraying) and spraying in the evening when bees and butterflies are generally not as active can help prevent unintentionally killing insects that can be helping to keep the bad guys at bay.
Speaking of butterflies, keep in mind that those beautiful creatures start out as what some would call “ugly” caterpillars. Those caterpillars need to eat in order to turn into butterflies, and often, what they are eating is what you have planted in your gardens. I had a customer in the store ask me how to get rid of the caterpillars that were eating his fennel every year. My answer was that he should just plant more fennel, so there would be enough for both him and those caterpillars, because they turn into beautiful black swallowtail butterflies! All butterfly caterpillars have a limited number of things they can eat — for black swallowtails, things in the parsley family, which includes parsley, dill, fennel, carrots, celery, cumin, and cilantro are on the menu. I always plant more dill and parsley in my garden than we will ever eat, with the hope of attracting the butterflies to lay their eggs in my garden. I also like to let some of my herbs go to flower to feed the adults.

In the flower garden:

Plant summer-blooming bulbs if you haven’t already. This includes dahlias, gladiolus, lilies, begonias and canna lilies.
Wait to trim back the foliage of your spring blooming bulbs, such as daffodils, tulips and alliums, until the foliage has died completely. Although you may be tempted to trim them sooner to tidy up, leaving the foliage will help the bulb use the sun’s energy to feed itself for next year’s blooms.
June is prime planting time for perennials and annuals, but be sure to water them in well when you plant them, and keep them well-watered throughout the season. Perennials will be spending the summer putting out lots of roots so that they can be well-established when winter hits. Those roots need good watering in order to grow well, and new roots aren’t as efficient at taking up water as established roots. Annuals, on the other hand, will spend the season putting on a show — they know they won’t make it past this season, so they concentrate on putting out lots of flowers that then turn to seeds. Keep them deadheaded, and they will just keep on producing more flowers in an attempt to produce seeds. Just remember that all that flower production needs water.
Annuals also need to be fertilized regularly throughout the season. Producing flowers takes a lot of energy, which uses up a lot of nutrients. Perennials generally only need one application of fertilizer each spring, as they are starting to put out new growth. For both types, a low-nitrogen, high-phosphorus fertilizer is best. Too much nitrogen can produce lots of foliage, but not a lot of flowers, and can cause some plants to get leggy and flop over.
The secret to keeping your container plantings blooming all summer long is to keep them fed and watered. As containers fill up with roots, they don’t hold water very well, so you need to be sure to keep them watered. And, since the plants are in a container, they can’t get their nutrients from the soil around them, unless you provide it. Just be careful not to over-water or over-fertilize, especially with chemical fertilizers. Too much of a chemical fertilizer can “burn” your plants — a sure way to kill them — and too much water will drown them. If your containers are in a sunny spot, check them at least once per day, and water as needed. Shady spots may not need as much water, but don’t forget about them. And even if we do get some rain, keep an eye on your container plants, as they tend to dry out faster than in-ground plantings.

Trees and shrubs:

Prune back early-blooming shrubs such as forsythia and quince after they have finished blooming. This will encourage new growth and more flowers next spring. Be sure to sharpen your pruners before getting to work. Dull pruners can cause a great deal of damage, and clean cuts heal faster.
Don’t “seal” pruning wounds when you prune trees. The old way of thinking was that you needed to, in order to keep diseases from setting in. New information has shown that it isn’t effective, and can actually cause more problems by keeping the area moist. These days, the only time sealing is recommended is if you prune an oak tree any time other than in the dead of winter. The reason for this is that the flowing sap of a freshly cut oak can attract insects that carry oak wilt disease, which is deadly to the tree.
You can pinch back evergreens once they have put out new growth. Pinching the new “candles” back by half will encourage them to bush out. But don’t cut into old wood, as most evergreens won’t produce new shoots from old growth.
Be sure your trees and shrubs have a good layer of mulch over their roots to keep them evenly moist, and to prevent weeds. Mulch should extend out to the tree’s dripline (the circumference of the tree’s canopy), but not be placed right up against the trunk.

Water trees and shrubs if we aren’t getting sufficient rain (like now). Newly planted trees and shrubs should be carefully watered for the same reason newly planted flowers need to be — they aren’t as good at taking up water while the roots are getting established. But be careful about how you water any tree or shrub. Water infrequently, but deeply. You want to encourage the roots to grow deeply, which won’t happen with frequent, shallow watering. Additionally, shallow, frequent watering can cause your plants to suffocate and slowly die. An easy way to keep trees and shrubs watered is with watering bags — just fill them up and walk away: they will slowly empty their contents directly to the soil around you tree or shrub.

For the Birds:

When you are out in your yard, keep an eye out for things like killdeer nests (they build their nests on the ground), and be careful to keep activity away from them as much as possible. Also watch out for baby birds that have left the nest but not yet mastered flight. They probably don’t need your help, unless they are somewhere where they might be in danger, like in the road, but do watch for them as you go about your yard to be sure that you aren’t putting them in danger with things like power equipment.
I had lots of Baltimore orioles at my feeders for a while earlier this spring, but they haven’t been coming to the feeders lately. I am hearing them in my yard constantly though, so I know they’re still around. Most likely, they’re busy feeding insects to their young, so aren’t coming to nectar feeders so much. My feeders are still out though. The hummingbirds are happy to drink from them, and once the oriole babies are out of the nest, the parents may bring them to the feeders to help them fatten up for the trip south at the end of the season.
Clean out and refill hummingbird and oriole feeders regularly. Sugar-water left out in the hot sun can quickly spoil, and become bacteria-filled. If it’s really hot, empty, clean, and refill the feeders every two to three days. When it’s not as hot, be sure to clean them out at least weekly.
Remember to clean out and fill your bird baths regularly. Birdbaths provide your birds with a place to get a drink or a good bath, and provide you with lots of entertainment, as you watch them playing in the water. With the heat we have been experiencing, clean water is even more important for the birds, so be sure to empty, clean, and refill baths each day.