Cool Season Vegetables Eventually Replace Warm Season Vegetables

Peppers do not grow in cooling autumn weather.

Just as warm season annual flowers that bloomed through spring and summer get removed to relinquish their space to cool season annuals, summer vegetable plants need to vacate the garden for cool season vegetables. Fortunately, removing vegetable plants is not as unpleasant as removing the pretty flowers might have been, because most have finished producing whatever it is that they were grown to produce.

Besides, cool season vegetables are even cooler than warm season vegetables, since some have distinctive foliage that is appealing beyond the vegetable garden, in borders, pots and mixed plantings, out in the landscape. Swiss chard is a striking foliar plant, whether it gets eaten or not. The outer leaves can get eaten without compromising the appeal of the inner leaves that continue to grow and fluff outward to replace them. Arugula, kale, mache, loose lettuce (non heading) and collard, mustard and turnip greens do the same.

This ability to function in more places in the landscape is a definite advantage since cool season vegetables are not quite as productive as warm season vegetables are. They would certainly like to be as productive, but grow slower through cool weather.

Most cool season vegetables should be sown into the garden as seed. Root vegetables, like beet, carrot and radish, might be available as seedlings in cell packs, but do not recover very well from transplanting. Besides, seedlings of such plants in cell packs are either too abundant and crowded, or to sparse to produce much. Leek, loose leaf lettuce and most of the greens likewise grow best if sown as seed in rows instead of planted in tight clumps as they are grown in cell packs.

Only greens that are grown as individual big plants, like chard, kale and collard green, can be as productive from cell pack seedlings as from seed. However, each cell pack produces only six plants, maybe with some extras. A package of seed costs about the same, but contains more seed than most gardens can accommodate.

Actually, the only cool season vegetables that might be more practical to grow from cell pack seedlings than from seed are broccoli, cauliflower, cabbage and Brussels sprout. These vegetables grow as even larger plants, so minimal quantities, like one or two or perhaps three cell packs, are sufficient.

Like so many of the warm season vegetables, many cool season vegetables should be planted in phases every two to four weeks to prolong harvest. By the time the first phase finishes, the next phase will be ready. The frequency of phases depends on the growth rate and duration of production of the particular plants. For example, chard has a long duration of production, so does not need many phases.

Radish

All parts of radish are edible.

Everyone seems to be familiar with radish, Raphanus raphanistrum subspecies sativus. It has been so popular with so many cultures for so long that its origin is now impossible to identify. It likely originated in Southeastern Asia at least two thousand years ago. After so many centuries, it has become remarkably variable in regard to flavor, form and color.

Radish are generally cool season root vegetables, although their foliage and flowers are also edible. They can be red, pink, purple, yellow, green, black or white, with white flesh. Their form might be almost spherical, cylindrical or tapered like a carrot. Small types are only about an inch to three inches long. Some daikon radish can get as long as two feet!

Because radish are typically smaller than most other root vegetables, they mature faster. Therefore, their seed can get started in their garden slightly later. If they mature too soon, warmth may cause them to bolt, which ruins their flavor and texture. Subsequent phases extend production, by resuming production as previous phases exhaust their production.

Cole Vegetables Are Cool Vegetables

Mustard greens are cultivated and naturalized.

September began with the warmest weather of the year. Such weather is not uncommon for late summer here. It can happen as late as early autumn. Still, it can be disconcerting while weather should be cooling. Cool season vegetable plants that are technically now seasonable dislike such warmth. Cole vegetables are particularly responsive to weather.

Cole vegetables are within the Cruciferae family, which is alternatively the Brassicaceae family. They therefore also classify as crucifers or brassicas. They include various forms of broccoli, cauliflower, cabbage, collard, kale, kohlrabi, mustard, turnip, radish, arugula, rutabaga and Brussels sprouts. As variable as they are, several are of the same species.

Broccoli and cauliflower are floral vegetables, since their primary edible parts are bloom. Brussels sprouts, cabbage, collard, kale, arugula, mustard greens and turnip greens are foliar. Turnip, radish and rutabaga are roots. Kohlrabi is a distended stem. Mustard seed, which is a seasoning instead of a vegetable, is the only common fruiting cole vegetable.

Therefore, unlike most warm season vegetables, cole vegetables should not fruit or go to seed. Broccoli and cauliflower only begin to bloom, but do not finish prior to harvest. This is why most cole vegetables are cool season vegetables here. Warmth stimulates bolting and bloom, which ruins flavor and palatability. Cool weather prolongs vegetative growth.

Contrary to the implications of recent weather, cool season vegetables, including several cole vegetables, are seasonable. This is the time to sow seed for turnip, radish, rutabaga and other cool season root vegetables directly into the garden. Transplant of seedlings is disfiguring to roots. Weather should be cooler by the time new seedlings start to develop.

Arugula, turnip greens, mustard greens, collard, kale and kohlrabi likewise develop most efficiently from seed. However, transplanted seedlings can be adequately productive too. Because only a few broccoli, cauliflower, cabbage and Brussels sprouts plants are likely sufficient, cell pack seedlings are likely more practical than seed. Since they are already growing, they can get planted a bit later.

Produce Fresh From The Garden

Cucumbers grow in spring or autumn.

Plants notice it before people do. They respond accordingly. Vegetative growth slows or stops completely. Most remaining bloom does likewise. Fruit and seed finish developing. Less fresh produce is available from the garden. Boston ivy and Japanese maples might already be changing color. They all know that the days are shorter and nights are cooler.

Warm season produce gets less abundant as summer ends because most is fruit, which contain seed. Most plants naturally finish with seed production prior to autumn. Most cool season produce is truly vegetative and lacking seed. It naturally grows during autumn or winter, with the (‘fruitless’) intention of blooming and fruiting during the following season.

It seems as if warm season vegetables were replacing cool season vegetables from last winter only a few months ago. Perhaps they were. That process began about half a year ago, but never completely stops. Various phases of various vegetables start and finish at various times. Now, some warm season vegetables might continue to produce until frost. 

Corn is of those warm season vegetables that remain productive. Seed for the last phase would not have been too late if it got into the garden two weeks ago, but will take time to produce. Broccoli seed sown at the about same time could be the first of the cool season vegetables in the garden. However, it is likely more practical to plant seedlings a bit later. 

Seed for cabbage and cauliflower can go into the garden now. Alternatively, it should do as well in flats or cell packs, for later planting. This procedure delays their occupation of garden space, which might still be occupied by late warm season produce. Besides, it is easier to defend tiny seedlings in flats or cell packs from slugs, snails, birds and insects.

For big and leafy cool season produce, it may be more practical to purchase seedlings in cell packs rather seed. Since only a few seedlings of each type are needed, they are not too much more expensive than seed. However, confinement to cell packs disfigures root vegetables, such as beets and carrots. Their seed can get into the garden in two weeks to a month.

Lettuce

Lettuce grows through cool spring weather.

On the coast between Los Angeles and San Francisco, lettuce, Lactuca sativa, seems to grow throughout the year. None of it actually grows in every season. Some varieties merely produce late enough for varieties that produce earliest to replace them. Slightly farther inland, lettuce is really only a cool season vegetable of early spring and autumn. The last new plants should finish by May.

There are many varieties of lettuce. Some are more tolerant of warmth than others. They perform well both late in their early season, and early in their late season. Others are more tolerant of cool weather. They can start early in their early season, and continue late in their late season. No variety produces through the coldest part of winter. Warmth initiates bolting (bloom), which ruins flavor.

The three types of lettuce that are most popular here are leaf, head and romaine. Leaf lettuce is the most variable. It can be blotched, bronzed or reddish, with variably ruffly texture. Some types of leaf lettuce mature in about a month. Some of the more substantial varieties of head and romaine lettuce start early, and can take nearly four months to mature. They can get to a foot wide and tall.

Vegetables From Winter To Summer

Bell peppers wait for warmer weather.

Cool season (or winter) vegetables are now finishing their season. Some continue to produce later than others. Eventually though, they all succumb to warming spring weather. As they do so, they relinquish their space to warm season (or summer) vegetables. Many warm season vegetables want to start growing as soon as possible. Later phases must wait for space to become available.

Later phases are no problem. They actually prolong the season for plants that are productive for only a brief season. For example, if sown at the same time, corn seed germinates and grows into stalks that produce all their corn at the same time. If sown in small groups every two weeks or so, corn seed grows into groups of stalks that produce corn every two weeks or so. That is ‘phasing’.

Phasing is more common with the cool season vegetable plants. Most of them are true vegetables, rather than fruits that are classified as vegetables. Individual plants produce only once, and can not produce again after harvest. Conversely, most warm season vegetables are actually fruits. (They contain seed.) Many of the plants that produce them continue to produce after harvest begins.

For example, squash, pole bean and indeterminate tomato plants that start growing in spring can continue to produce until frost. (Determinate tomatoes and bush beans have shorter seasons, so can benefit from phasing.) Cucumber vines can produce until frost, but might get shabby enough (from aridity) for replacement halfway through their season. Pepper and eggplant thrive in warmth.

The various greens and the various root vegetables, which are truly vegetative rather than fruiting vegetables, should grow in phases.

Seed for corn, bean, root vegetables and most greens should go directly into the garden. Seedlings do not transplant well, and are expensive in sufficient quantity. Romaine and head lettuces are exceptions that produce well from seedlings. Tomato, pepper, eggplant, cucumber and squash seedlings transplant easily. If only a few are required, they are not much more expensive than seed.

It Will Soon Be Autumn

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Cool season vegetables replace summer vegetables.

From the time they get planted in early spring, tomato plants are expected to perform a bit better than they did earlier in the season. They start out with only a few early tomatoes, but quickly become prolific. Production continues to increase as the plants grow all through summer . . . until now. Newer leaves on top are not staying so far ahead of fading leaves below.

While the weather is still warm, it is difficult to say how tomato plants know that autumn will soon replace summer. They do not seem to be intelligent enough to realize that every day is imperceptibly shorter than the one before. Nor do they seem to be sensitive enough to notice if the nights get slightly cooler. They just know, and they tell all their friends.

If zucchini plants have not started to fade and sag, they will soon. As weather cools, they no longer grow faster than the mildew that they tolerated all summer. Any fruits that are present now should have time to finish developing, but there probably will not be many more after that. (Zucchini fruits are eaten before mature anyway.) Other warm season vegetables are in a similar state.

Acorn, Hubbard, butternut and other winter squash grow through summer just like summer squash do, but are not harvested until the vines wither in autumn and winter. Unlike summer squash that continue to produce many tender juvenile fruit to replace what gets harvested through summer, winter squash plants put all their effort into one or two large ripe fruit.

Warm season vegetable plants still need to be watered as the foliage slowly deteriorates. They only begin to need less water as they lose foliage and the weather gets cooler. They may like to be fertilized one last time, but will not not need it again. Any last phases of corn will stay thirsty later than other vegetable plants because they deteriorate slower, and are rather thirsty anyway.

Seed for broccoli, cauliflower, cabbage, kale and certain other cool season vegetables can be sown in flats or cell packs now so that their seedlings are ready to go when the warm season vegetables relinquish their space in the garden. If space allows, seed for beet, turnip and turnip greens can be sown directly into the garden. Carrot seed should still wait for cooler weather.

Winter Vegetables Start In Summer

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There are vegetables for every season.

It seems to be much too early for cool season vegetables while the weather is still so warm. Summer vegetables, which are also known as warm season vegetables, are still at their best. Most will continue perhaps until frost. Yet, months ago, they also started prior to their growing season. At that time, cool season vegetables, which are also known as winter vegetables, were still producing.

Although it really is too early for winter vegetables to grow in the garden, it is time to plan for them. Those of us who prefer to grow varieties of winter vegetables that are not likely to be available in nurseries should get their seed now. In only a few weeks, it will be time to sow the first phase of seed for carrots and beets directly into the garden. By October, it will be time to sow seed for peas.

Broccoli grows slowly from seed. Whether it goes directly into the garden, or into flats for later transplant, broccoli seed should get sown by about now. If the preferred gardening style allows for it, seed for winter vegetables can be sown below old summer vegetable plants. The seed for winter vegetables can germinate and start to grow as summer vegetables finish and vacate the garden.

Cauliflower and cabbage seed want to germinate and start growing shortly after broccoli, within the next few weeks. However, seedlings of the more popular varieties of cauliflower and cabbage, as well as broccoli, will be available in nurseries for later planting. Lettuce, spinach and kale do well from late seedlings, or seed sown after cauliflower and cabbage, along with carrots and beets.

Root vegetables, like carrot, beet, radish, turnip, rutabaga and parsnip, grow from seed, sown directly.

Eventually, some of the warm season or summer vegetables will need to relinquish their space to winter vegetables. Most will finish by that time anyway. Those that stay long enough will succumb to frost. Summer vegetables can stay latest where subsequent phases of winter vegetables will later (not yet) replace an early phase. Subsequent phases begin production as early phases finish.

Carrot

91002Bugs Bunny was an expert. He was always chewing on a carrot, Daucus carota, and rudely talking with his mouth full. Because carrots can be stored in refrigeration for a few months, Bugs Bunny could get one whenever he wanted to. However, in home gardens, they are cool season vegetables that are grown through spring and autumn, but not through summer or the middle part of winter.

Carrots are biennial. They complete their life cycle in two seasons. They are vegetative during their first season, as they produce their edible and elongated conical taproot. If not harvested, they bloom and go to seed in their second season. By then, their fat roots are tough and useless. Carrots are ready for harvest in three to four months after their seed are sown, depending on variety.

Carrots are famously bright orange. Yellow, white, red, purple and black varieties have been gaining popularity in the past many years. The longest carrots might be a foot and a half long, but most are less than half as long. Many are only about four inches long, or less. They may be as narrow as half an inch, or wider than two inches! Some carrots are more uniformly cylindrical than conical.

Get Cool Season Vegetables Going

91002thumbThe difficult part will be removing the aging warm season vegetable plants while they are still trying to produce. That is one of the disadvantages of gardening in such an excellently mild climate. It would be easier if frost or cooling weather caused them to start deteriorating by now. Perhaps some are already getting tired. Regardless, their space is needed for new cool season vegetables.

Some of us like to amend the soil in between some of the lingering warm season vegetable plants, and add seedlings of cool season vegetable plants. Then, there is less of a rush to remove the warm season vegetables as they succumb to autumn weather. Some of us just wait for the warm season vegetables to finish, which is a delaying compromise for the new cool season vegetables.

Whatever the preferred technique is, it is now getting to be time to plug in seedlings of broccoli, cauliflower and cabbage. Kale seedlings may be added as much as a month later. Seedlings can be purchased from nurseries. Those of us who want particular varieties that are unavailable in nurseries might have sown preferred seed in flats a month or so ago, to be ready for planting now.

Beets, carrots and turnips, like all root vegetables, should be grown from seed sown directly into the garden. Roots get disfigured if grown in flats or cell packs, and then transplanted. Besides, so many individual plants are needed, that such quantities of cell packs would be expensive. Seed for turnip greens, although not grown for their roots, likewise gets sown out directly, and about now.

Seed for leafy lettuces, spinach and peas should have been sown already, but it is not too late. Kale can alternatively be grown from seed sown directly now, rather than from seedlings plugged in later. If preferred, larger heading lettuces can be grown from seedlings plugged within the next month or so. Cucumbers can be risky. If seed has not yet been sown, seedlings can still be plugged.

Whether grown from seedlings or seed, this is only the first phase of cool season vegetables. For some, later phases will prolong harvest.