Vegetables are divided into warm season and cool season crops. Different classes of vegetables require different amounts of heat in order to grow.
Plants that we harvest for their fruit (the part of the plant in which seeds are produced), such as tomatoes, squash, peppers, eggplant, melons, and lima beans, need ample heat and long days.
Cool season plants, on the other hand, do well when the temperature is on the low side. These are the leafy and root vegetables, such as carrots, beets, spinach, cabbage, and lettuce. Peas qualify as a cool season plant even though the fruit is harvested. When the weather is cool and the days short, these plants put all their energy into forming leafy or root materials, but when the days warm up, they stop this activity and start going to seed.
In addition to warm season and cool season vegetables, there are early and late varieties of most vegetables. The early varieties require less heat to mature than the late ones.
If you live in an area where the temperature never rises above the 70s during the summer, you might want to plant only early varieties (see Seed Sources). It is important to choose varieties that are right for your growing season.
For quick reference, vegetables can be divided into three categories:
- Cool season crops (adapted to 55-70 degrees F) tolerant of some frost: asparagus, beets, broccoli, brussels sprouts, cabbage, kale, mustard greens, New Zealand spinach, onions, radishes, rutabagas, spinach, turnips.
- Cool season crops intolerant of some frost at maturity: carrots, cauliflower, endive, lettuce, peas, rhubarb, Swiss chard.
- Warm season crops (requiring 65-89 degrees F day and night) readily damaged by frost: beans, corn, cucumbers, eggplant, melons, okra, peppers, squash, tomatoes.
Intensive Plant Spacing in Inches
asparagus…12 beans (bush)…4 beans (pole)………6-10
beets………….2-3 broccoli………..15 brussels sprouts…16
cabbage…….12 carrots …………1-2 cauliflower………….16-30
corn……………8 cucumbers…….4 eggplant……………..25
kale……………16 lettuce (butterhead)..4-5 lettuce (head)……..10
lettuce (leaf)…5-10 melons (supported)..12-24 mustard greens…..4
New Zealand Spinach..8 okra………………15 onions………………..2-3
peas (supported)…2 peppers………..12-24 radishes…………….2
rutabagas……6 spinach………….6 squash (bush)…….18
Swiss chard..6 tomatoes (cages)…..18 turnips………………..3
How to Start Vegetables
You have a choice.,
- For some vegetables, such as carrots, beets, and other roots, you should sow seeds directly in the ground.
- For broccoli, cabbage, cauliflower, lettuce, onions, tomatoes, and several other vegetables, you can buy seedlings from the nursery and transplant them directly into your garden.
- For most vegetables, you can plant seeds in containers indoors and then later transplant the resultant seedlings outdoors when the weather warms up.
If you are starting your plants from seeds they need to be hardened off before transplanting into the garden. Introduce them to open-air temperatures by putting them outside (in their containers) when it’s sunny. Bring them indoors whenever frost seems likely, especially overnight. Expose them to lower temperatures for about two weeks before setting them out in your garden bed.
Stretching Your Crops
Any gardener can learn little tricks that make Mother Nature work overtime. These miracle “crop stretchers” are intercropping, succession planting, and catch cropping.
Intercropping simply involves planting quick-maturing crops between slower-maturing crops. You can plant quick-maturing radishes, green onions, or leaf lettuce between corn and tomato plants. Because you plant the corn and tomatoes far apart, you will harvest the crops between them before the corn and tomato plants have grown big enough to crowd the smaller plants out. That’s getting double duty out of your intensive beds.
Succession planting consists of planting a crop as soon as you take out an early one. (Make sure you add compost, manure, bonemeal, and wood ash, or appropriate substitutes, before you replant). For instance, you can harvest spinach and then plant beans or take out broccoli and then plant corn. Or you can successively plant early season, mid-season, and late season varieties of the kind of vegetable. Any combination of early and late varieties expands the productivity of your garden.
Catch cropping is planting quick-maturing plants in places where you just harvested larger, slower-growing vegetables. You can harvest a couple of broccoli plants in late summer, for instance, and grow radishes or green onions in the same space. The basic rule for catch cropping is: Don’t leave bare ground unplanted.
Seed Planting Tips
What do the instructions on seed packages mean by “plant as soon as the soil can be worked in the spring”? Obviously, frozen soil can’t be worked. When thawing, it’s too wet. Usually, about two weeks of sunny, breezy, above-freezing weather dries the earth enough to make it ready. A trusty rule of thumb is to walk on the garden: If mud sticks to your shoes, wait another week. If your shoes stay clean, plant now.
Fine-Tuning the Season
Some seeds like wet soil for germination; other prefer it semi-dry. This is known as the “soil moisture range.”
- Cabbage, carrots, cucumbers, muskmelons, onions, peppers, radishes, squash, sweet corn, tomatoes, turnips, and watermelon germinate over the full moisture range from wilting to field capacity (the maximum amount of moisture the soil can hold).
- Beets, endive, lettuce, lima beans, peas, and snap beans germinate best in the upper half of the soil moisture range.
- Celery germinates only when the soil moisture is near or above field capacity.
- Spinach and New Zealand spinach germinate best in the lower two-thirds of the soil moisture range.
Such seeds as okra and asparagus sprout easily if you crack their tough coats. The easiest way to do this is to roll the seeds gently between two blocks of sandpaper until their ridges are worn down; then soak them overnight before planting. This technique will shave days off their germination time.
Work Up a Lather
To sprout parsley, parsnip, and beets, scrub them in a pint of warm water. If the water is hard, add half a cup of vinegar. Lather your hands with mild bath soap (not detergent), rub the seeds in your hands, rinse them in this acidified water. Then soak the seeds overnight in this same water. Next day, drain the seeds on a towel and plant them before they dry out.
There’s a handy rule of thumb for seed depth. Plant at a depth four times the diameter of the seed. In wet weather or heavy soils plant a little more shallow; in light or sandy soils, plant a bit deeper.
Difficult Seed Sowing
Trying to sow a fall garden in the heat of summer? Here are four methods gardeners use to get their fall crop up and growing fast.
- Cover the seeds with one-by-fours or one-by-sixes. Lift the boards daily to check for sprouting. Once a few seedlings break through the ground, remove the boards.
- Cover with strips of porous cloth mulch. You can water directly through this. Remove the cloth once the seeds germinate.
- A thin layer of grass clippings preserves moisture and helps seed germinate quickly. The clippings stay in place while the plants grow to maturity.
- Cover your seeds with a thin layer of potting soil. This prevents crusts from forming and retains water while the seeds germinate.
When selecting seedlings from a nursery, choose well-established plants with at least four true leaves and a healthy green color. Eggplants, peppers, and tomatoes should be wider than tall. Protruding roots means the plant is root-bound;premature fruiting means the pot is stressing the plant; leggy, leaning plants were grown in inadequate light.
Chopsticks make a good planting tool when you want to use cell paks (growing containers) or small pots. Wooden chopsticks work best. After you get the hang of it, the process of picking up the seeds and twisting them into the soil goes quickly. Push the soil back over the holes to cover the seeds.
If you have trouble with damping-off (a disease caused by fungi that makes seedlings wilt or rot) when starting seeds in pots or flats, try planting them first in vermiculite. Sow the seeds 1/4-1/2 inch deep in a pot or flat filled with moistened vermiculite. Pat the vermiculite firm, water lightly, and slip the seedlings into a plastic bag. This keeps them moist when the first true leaves form. Transplant them to pots or peat pots. This process almost guarantees success.
Before planting seeds in pots, cut some plastic bags into squares, poke holes in the bottom of the plastic (for drainage), and place one square inside each pot. Fill the pots with soil and seed. When transplanting time comes around, just lift the plastic squares out and your plants can be gently settled into the ground. Once in the ground gently pull the plastic away and discard.
Seeds that have sprouted in flats need to be picked out and placed in another container as soon as the seedlings are large enough to handle. Use a pointed stick to lift the seedling from under its roots. Always handle seedlings by the leaf, not the stem. A new leaf will soon replace a damaged one, but it’s impossible to replace a stem.
Tips on Protecting Seedlings
Stop the shock
A number of tricks can alleviate transplant shock so your seedlings suffer little setback or delay in growth.
- Start with small seedlings. Four to six leaves are enough.
- Transplant at sundown or on a cloudy day.
- Wet the soil thoroughly around the seedlings’ roots a few hours before you go to work so the plants will be plump with water.
- Dig the holes before you uproot any seedlings. Fill the holes with water, and let it soak in.
- Move one plant at a time, but do it quickly. Don’t delay.
- Immediately soak the soil around each transplant. Don’t wait until you have completed the bed. Sprinkle the transplants daily.
- Transplanting experts often move little clumps of plants at a time so as not to damage roots by pulling individual plants apart. After the plants have taken you can thin them out.
Quick Seedling Protection
To protect seedlings against frost, almost anything will do; homemade paper hats, clear plastic cake covers, a milk carton cut in half, some flat cardboard folded over, a cardboard box with both ends cut out and the top end covered with clear polyethylene. Just use your imagination.