When to plant outside (part 4)

Part 4- an introductory guide to growing food - planting outside

I once met a lady at a garage-sale-style plant sale I had many years back. It was Mother’s Day weekend. She lamented that she had planted tomatoes not once, not twice, but three times already, and they had been killed by frost. She was at my plant sale to buy more tomatoes. I felt bad for her (and the casualties). It’s a tough lesson in Colorado weather, just how much tomatoes hate cold weather, and the importance of timing. 

Sometimes you will hear to plant your garden around Mother’s Day, but let's take a deeper look at that for here on the Front Range of Colorado. There are a few important things to consider, including whether you have cool or warm season veggies, that I will discuss below. Here, we often have frost on or past Mother’s Day, around May 15th. But wait! Even after the threat of frost passes, temperatures still need to rise for warm season veggies to truly thrive. There is not one "right" answer to any of this. There are a lot of opinions and preferences depending on who you talk to. So please take this as general guidance, and not anything that is set in stone. Over time, you will develop a feel for what works best for you :)

Know if you are growing tender, warm-loving vegetables, or cold-tolerant, heat-hating vegetables

Hang with me for a moment. Some crops you can and should plant on or before Mother’s Day, but they should be ones that are frost tolerant. More on this below. 

First, let’s talk about warm season veggies

• Most of the nightshade family (tomatoes, peppers, tomatillos, eggplant)

• Cucurbits (squash, zucchini, pumpkin, cucumbers, melons)*

• Corn*

• Beans*

• Basil

  *best direct sown

Here is a rule of thumb for warm season veggies. Ideally these should be planted when nighttime temperatures are in the 50s. They need warm soil temperatures to thrive (over 70 degrees F), and for proper uptake of nutrients. Often this doesn’t happen until the last weeks of May or first week of June on the Front Range. I recommend waiting until around Memorial Day (or the last couple of weeks in May, since Memorial Day varies) for the best success. If you plant before this, the plants will sit, stall, and wait for the warmer temperatures to really start growing. Root development will be poor if they are planted in cool soil. That said, some years the warm season arrives earlier. So, start looking at the forecast the first or second week of May, and plan on a tentative date to plant, being sure to check again to see if things still look favorable. As long as you are not growing tomatoes or peppers that are extremely late varieties, you’ll have plenty of time to harvest even if planting the first week of June. An added benefit is that this bypasses some of the early hail storms as well  (depending on your particular microclimate). You will save yourself and your plants stress if you wait for the weather to warm up. It can be hard, I know! Remember to count back a week or two to begin hardening off your plants. 

I hate to add another consideration that complicates things, but 2020 was a year it was really hard to plant in a "perfect" window. In years where it gets really hot really fast, waiting too long has the drawback that the plants are stressed during transplanting and might have a hard time getting established if the temps shoot into the 90s early in June. Just use your best judgement and don't sweat it too much.

Those that do start early often know the risks, and protect their plants when the weather gets cold. Just as an FYI to brand new gardeners, this can become a lot of work, so just beware if you do decide to plant your warm season veggies early. It doesn’t get you much of a jump start on the season since their growth stalls until temperatures rise. Be prepared to replant. Some people protect their plants with things like a Wall O’ Water. This provides insulation. But these are an added expense, are not practical when you have dozens of plants to protect, and don’t buy you a lot of extra time in the growing season. Some people use them, and like them, and if this is what works for you, great! My friend planted a couple tomatoes in mid April 2021 and protected them with Wall O' Waters and frost cloth over top, and they did well through a deep freeze. It's just a matter of determining if you want to do this or not. In general, my advice is - If you can wait, wait. I know we all get antsy, but your plants will do better with putting them in the ground when they will be the happiest. 

Adding this note May 3, 2021 - I am going try putting out a few tomatoes to experiment, and see how they fare being planted out a week or two before the other ones. I'll try to remember to report back how they do compared to ones planted out later. Update: There wasn’t a noticeable difference by July. The ones planted out later seemed to catch up. 

Cool season veggies

These are veggies that are frost tolerant, can handle some snow, and don’t do as well when the hot temperatures of summer arrive (sometimes bolting - going to seed). Some of these are best direct sown, see below.

• Lettuce, swiss card, spinach

• peas

• Brassicas (aka cole crops) - cauliflower, broccoli, brussels sprouts, kale, cabbage, kohlrabi, mustard greens

• Root veggies like radishes, beets, carrots

• onions

These should be planted before the date of last frost for best results. Some are more heat tolerant and can be planted during a large window of time (e.g. swiss chard performs very well for me in a part sun location all through summer, and even lasts well into winter as well).

Refer to this calculator for transplanting. Enter your date of last frost (I suggest using ~May 15th if you’re in the Fort Collins/Loveland area or Colorado Springs) and look at the setting-out-date column.

Quick transplanting tips

Choose an overcast day if possible to transplant. If not, wait until the heat of the day has passed, and then plant. When you transplant, be mindful of spacing (Part 1 has some general advice on planning your layout and spacing). Some plants that are heavy feeders will appreciate an extra scoop of compost mixed into their holes (or a granular fertilizer). These would include cucurbits, tomatoes, and peppers. Gently press around the plant to remove big air pockets, and water in well. They may droop for a short time, but as long as they’re well watered, they should bounce back quickly. 

Direct Sowing

As I discussed in Part 3, there are a variety of ways you can buy or get free plants. But what about ones that are best direct sown? A list of common plants that are better off being direct sown, either because it is easier than bothering with starting indoors, or because they do not transplant well:

• Warm season:

  • Cucurbits (winter and summer squash, cucumber, melon) (note: I do start some indoors, and direct sow as well for insurance)

  • Beans

  • corn

  • Cool season:

    • Root vegetables (carrots, radishes, beets)

    • Peas

    • Lettuce

direct sown beans, late May

Follow the directions for sowing on the seed packets and keep the soil from drying out. 

The benefits of direct sowing are 

• you bypass the work and additional time involved sowing them indoors

• they can take off and grow in the garden, no transplant shock or slow-down

• You don’t risk disturbing roots of plants that are sensitive to this

beans sprouting

Here is the chart I like to share as a reference for when to direct sow and transplant. Many crops can be succession planted so that you can have a continuous harvest. Though this is created for Northern Colorado, it applies to Colorado Springs as well in my experience. 

What about hail? The Front Range is notorious for getting late Spring and sometimes beyond hail storms. It’s been known to take out entire gardens, or badly damage them. One way to avoid *some* of the struggle - plant later. As discussed above, this has many benefits. Late May through early June is a good window. That said, I have had June hail storms punch holes in my plants and even take out a tomato plant with a direct hit. Sometimes you have bad luck. If you know the hail is coming, you could take measures to protect small plants by putting buckets, weighed down cardboard boxes, or other plastic containers you have over them. The problem is, sometimes you don’t know it’s coming, or you aren’t home. 

Some people consider hail protection a must, and some microclimates along the Front Range get more severe hail, more consistently than others. There have been storms where I had no hail, and my friends' gardens were mostly destroyed or beat up. Since installing hail protection is quite an investment in both materials and labor, here’s what I recommend. 

• Talk to your neighbors. Do their gardens get destroyed by hail? Does it do little to no damage most years, but every few years is bad? Which month(s) does it usually happen? 

• If it's typically bad, or you just don't want to have to worry about it, consider putting up hail protection immediately. 

• Another option is to try out gardening for a few seasons, observing and accepting what happens, and if you still love growing food and have experienced bad damage from storms, then look into more serious measures such as installing hail cover over your beds. Otherwise, just roll with what Mother Nature throws at you. If your plants are strong and healthy, a few broken stems and punched-through leaves (or even more extensive damage) will be just a blip and you may be surprised by the comeback they make.

• In the end, it’s what feels right for your circumstances and how much effort and expense you are willing and able to put in.

In the next part of this series, we’ll talk about maintenance and caring for your plants during the growing season (coming soon).