When is the right time to plant tomatoes along the Front Range? Is it still too cold, is the soil dry enough, when’s the next snowstorm, but I want to plant!
Technically we haven’t had consistent nights in the 50s to officially plant warm-season crops, the vegetable and herb plants that require warmer nights for continuous growth. Cool-season crops like spinach and kale shrug and happily grow when nights are in the 40s, even high 30s, if they’ve been growing a few weeks.
If you held off planting tomatoes (and peppers, eggplant, green beans and other warm-season crops), you probably made a good call. Or if you’re using cold frames or keeping them toasty at night under blanketed tunnels, good for you. You may win the first ripe tomato in the Fourth of July contest.
I’m old school. I want to plant tomatoes, peppers, basil, squash, beans and eggplant in the ground on a 65-degree. partly cloudy day with steady nights above 55 and a slow warming trend ahead. Lately, it’s still in the chilly 40s overnight. But we’re getting close. My official planting target is in a few days, since it’s looking consistently warmer. (Will it then get too hot too soon? Probably.)
Let’s give tomatoes the best opportunity to grow healthy, abundant and hopefully disease-free this season.
You should have your warm-season transplants purchased or self-grown by now (or soon.) If they have been growing inside a garden center or under lights in your home, they need to be toughened up for the transition to outside life by acclimating them slowly over a period of days. This universal process is termed “hardening off,” and is advised for any plant, not just tomatoes that were growing inside. There’s nothing worse than having your well-cared-for seedlings croak on day one from being abruptly exposed to Mile High sun, wind and heat.
Start by putting plants outside in a shady, windless area for a few hours, then increase the time outside each day. After a couple of days, move them to a sunny location for half a day, then back into shade. Bring them inside or to a garage at night when temperatures are still in the 40s. Keep an eye on their water needs; they dry quickly in small containers. After about four to six days, they should be ready for prime-time growing.
The sunlight location you choose needs to match what the vegetable or herb requires for optimal growth. Try to rotate where you plant from year to year to aid in the prevention of soil-borne diseases and pests that can be introduced by certain crops.
Plant deeply in good soil that is prepped with an amendment or fertilizer. A soil test would tell you exactly what the soil might be lacking in nutrients (too much or too little) and recommendations for improvement. Do the test early next spring if you forgot this year.
Water the transplant well a few hours before transplanting so the root ball stays together and is easier to place and plant. Pluck any flowers growing on the plant while it is in the container; when planted, the transplant will focus on root growth versus energy to flower and fruit.
Dig a wide hole where the tomato will be planted, deep enough to leave just the top growth.Carefully cut off any side branches up to the top growth. I pre-clean my small scissors so there’s no chance of disease transfer from last year or yesterday. (Sterilize tomato cages, too. Why take any chances?)
Next, carefully remove the plant from the container, even from peat-based containers, which will not easily break down in our soils like they do in other parts of the country.Carefully set the plant in the bottom of the dug hole. Gently fill in the soil around the plant, water when half the hole is filled with soil. Finish adding more soil to fill in the hole and water again. There should be just a set or two of top leaves showing.
Wherever side growth is removed, roots will develop in the planting hole which makes the plant much stronger. Place a stake or stick next to the root ball for plant support as it grows. (Adding it later may damage plant roots.) If planting in a pot, use the same procedure if the container is deep enough.
Trench planting a tomato on its side works well if a deep hole cannot be dug in the garden space. Dig a long trench the length of the plant. Remove side shoots and leaves and carefully lay along the trench, with the remaining top leaves at the end. Cover soil over the length of the plant so the soil is even with the rest of the area. There should not be a mound; if there is the trench isn’t deep enough. Place the stake next to the foliage. Water all along the soil-covered trench since that’s where new roots will grow.
(Check out my Denver Post video on planting leggy tomatoes.)
After planting, place a large cage over indeterminate tomatoes (types that produce fruit until frost and get very tall). Smaller, determinate or compact (dwarf) tomatoes often don’t need staking, but it’s not a bad idea to do so.Mulch the plant with chemical-free grass clippings, weed-free straw or biodegradable paper.
Watch the weather — always. If strong winds or storms are forecast (please, pretty please no hail) be ready to cover your plants before the torrential rain hits. Buckets, plastic garbage cans, even large boxes with weighted rocks or boards on top work in a pinch. Go the extra step if you wish and invest in some inexpensive rebar or garden posts and place around the plants that need the most protection. Then clip on lightweight sheets, floating row cover or netting to protect from hail and heavy rain.
Unfortunately, storms can ruin a garden in minutes if you are not prepared.
Betty Cahill speaks and writes about gardening in the Rocky Mountain Region.
