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Weather finally right for tender plants to hit the garden

| Thursday, May 18, 2017, 8:55 p.m.
Doug Oster | Tribune-Review
When choosing plants for containers, pick varieties that like the same conditions. These double impatiens and caladiums both love the shade.
Doug Oster | Tribune-Review
Peppers love warm soil and air temperatures. They will thrive when planted in June and later.
Doug Oster | Tribune-Review
This container uses the basic planting principle of thriller, filler and spiller. The thriller is the blue agapanthus, fillers are pink begonias and the spiller is creeping Jenny.
Doug Oster | Tribune-Review
This tomato has septoria leaf spot an early season fungal disease. There are many ways for gardeners to fight off the disease.
Doug Oster | Tribune-Review
'Super Chili' is one of Doug Oster's favorite peppers. Straw mulch will keep the soil evenly moist and help ward off blossom end rot.
Doug Oster | Tribune-Review
When choosing plants for containers, pick varieties that like the same conditions. These double impatiens and caladiums both love the shade.

The third week of May marks the traditional start of planting for tender crops in the garden. But even though things like tomatoes, peppers, impatiens and a host of other plants should be fine, it's important to watch the weather forecast for a sudden temperature drop.

I know gardeners that have already put frost-sensitive plants in and even watched from afar as people bought them a month ago. It took everything I had in me to stop from running over to the box store screaming "stop, stop." Memorial Day is when Mom always said to plant and Mom is never wrong, just ask her. It's the absolute definitive frost-free date.


One thing I always wait to plant are peppers, which love warm soil and air temperatures. I usually get them in the ground the first week of June, but will continue to plant them into July. For later plantings, it's important to choose a variety that only takes a couple months to produce ripe peppers.

One trick is to cover the pepper bed with black landscape fabric a week or two before planting. It helps warm up the soil. It could be left in place after cutting holes for the plants. I remove it and just mulch the plants with straw. Even though it cools the roots a bit, keeping the soil evenly moist will make the plants happy and fight off blossom end rot. 'Super Chili' is one of my favorite hot peppers for late planting as it puts on tons of fruit quickly and will wake you up when biting into them, especially after they've turned red.


Tomatoes are prone to fungal issues when planted this time of the year, especially if we have a cool wet start to the season. Early blight and septoria leaf spot are the most common culprits. Give the plants plenty of room, at least 3 feet between each for good air circulation, and grow lots of different varieties. Each cultivar deals with diseases differently.

Mulching on planting day will hopefully stop the soil-borne spores from splashing up on to the leaves. Removing the lower leaves of the plant will make it harder for the spores to make it up to the plant too.

Just like the peppers, I'll leave room in the tomato bed for succession planting. The main crop goes in now, but plants are added weekly all the way through July 4th. The last planting is a cherry or other early producing variety. Since they haven't lived out in the cool, wet weather, the plants aren't usually affected by the fungal diseases.

When all else fails an organic fungicide like Serenade will help keep the problem in check.


A few years ago there was an outbreak of downy impatiens mildew, which will kill impatiens if they become infected. The disease has been around since the 1800s and hit gardeners hard in 2013. Since then growers have worked to be sure plants are not infected before being sold and that's really helped to keep plants healthy.

The disease can still be a problem, but usually doesn't get to the plants until very late in the season. New Guinea impatiens are immune to the disease as is a variety named 'Bounce.'

I'm planting impatiens as I normally would though. A great shade-loving combination that I've had fun with the past few years has been teaming double impatiens with caladiums. The caladiums are grown for their beautiful foliage and their tubers can be saved similar to dahlias or left to freeze like other annuals. I chose caladiums and impatiens to grow together as they both love shade. By picking the right plant for the right place, you'll be a more successful gardener.


For plants that are going out in the garden, the key to having a green thumb is improving the soil. Compost can be bought by the bag or truckload and when added to the garden will give the plants everything they need. Creating a shallow depression at the base of each plant will help it retain water after a rain.

As each plant goes in the ground give it a drink instead of waiting until all the planting is done at the end of the day. When they need water during the season, soak the plant at the base in the morning when possible. By watering early, it give the plant a good start to the day and allows the leaves to dry off, preventing fungal issues.

Feeding plants every couple weeks with a liquid organic fertilizer will have them growing strong through the season.

The official start of the season is thrilling as it won't be long until we're enjoying tomatoes out of the garden and lush blooms too.

Doug Oster is the Tribune-Review home and garden editor. Reach him at 412-965-3278 or or via Twitter at @dougoster1. See other stories, blogs, videos and more at .

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